Sputtering target material and sputtering target

Abstract

This invention provides a sputtering target material with excellent properties. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. The sputtering target material has a Vickers hardness of 460 or higher and a flexural strength of 90 MPa or higher when its volume resistivity at 25°C is less than 6.0 × 10¹¹ Ω·cm; or a Vickers hardness of 250 or higher and a flexural strength of 90 MPa or higher when its volume resistivity at 25°C is 6.0 × 10¹¹ Ω·cm or higher.

Description

Technical Field

[0001] This disclosure relates to a sputtering target material and the sputtering target. Prior Technology

[0002] As a material for manufacturing piezoelectric thin films, sputtering target materials containing sintered bodies of oxides containing potassium, sodium, niobium, and oxygen are sometimes used (hereinafter also referred to as KNN target materials or simply target materials) (see, for example, Patent Document 1). [Existing Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2011-146623 Summary of the Invention

[0004] [The problem that the invention aims to solve] The purpose of this disclosure is to improve the properties of KNN target materials. [Methods for solving problems]

[0005] According to the present invention, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. When the volume resistivity at 25℃ is less than 6.0×10 11Ω·cm, the Vickers hardness is above 460 and the flexural strength is above 90 MPa.

[0006] According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. When the volume resistivity at 25℃ is above 6.0×10 11Ω·cm, the Vickers hardness is above 250, and the flexural strength is above 90 MPa.

[0007] According to another aspect of this disclosure, a sputtering target is provided, comprising: The sputtering target material as described in any of the states; and Backplate, bonded to the sputtering target material. [The effects of the invention]

[0008] According to this disclosure, the properties of KNN target materials can be improved. Brief Description of Drawings

[0009] FIG. 1 is a diagram showing an aspect of the target material 10 of the present disclosure. FIG. 2 is a diagram illustrating the manufacturing process of the target material 10 of the present disclosure. FIG. 3 is a schematic structural diagram of the sintering apparatus 100 used in the present disclosure. Embodiment

[0010] <An aspect of the present disclosure> Hereinafter, an aspect of the present disclosure will be mainly described with reference to FIGS. 1 to 3.

[0011] (1) Structure of the target material The target material 10 in this aspect is mainly composed of a sintered body containing an oxide (alkaline niobium oxide) containing potassium (K), sodium (Na), niobium (Nb), and oxygen, that is, a KNN sintered body. The crystal grains mainly constituting the KNN sintered body have a perovskite structure. Specifically, the KNN sintered body is represented by the compositional formula (K1−xNax)NbO3 (0 < x < 1), and the coefficient x [= Na / (K + Na)] in the compositional formula is 0 < x < 1, preferably 0.4 ≦ x ≦ 0.8. The KNN sintered body constituting the target material 10 in this aspect is an oxide sintered body substantially composed of potassium, sodium, niobium, and oxygen, or an oxide sintered body further containing a doping element shown below. Here, the term "substantially" means that more than 99% of all the atoms constituting the KNN sintered body are composed of potassium, sodium, niobium, and oxygen, or when the KNN sintered body contains a doping element, it is composed of potassium, sodium, niobium, oxygen, and the doping element.

[0012] The composition ((K + Na) / Nb) of K, Na, and Nb in the target material 10 satisfies the relationship of 0.90 or more and 1.25 or less, more preferably 0.95 or more and 1.20 or less, and even more preferably 1.00 or more and 1.10 or less. Furthermore, K, Na, and Nb in the (K + Na) / Nb formula here are the numbers of K atoms, Na atoms, and Nb atoms contained in the KNN sintered body, respectively. Furthermore, the composition ratio of the target material 10 can be estimated based on the input amount of the raw materials, but can also be measured by a known method. For example, it can be obtained by using an inductively coupled plasma optical emission spectrometer (inductive coupled plasma-atomic emission spectrometer (ICP-AES) (for example, SPS5000 manufactured by Seiko Instruments Inc., etc.)).

[0013] In the target material 10, at least one element (dopant) selected from the group shown below is sometimes added, for example, at a concentration of less than 5 at%. Examples of dopants include at least one element selected from the group consisting of lithium (Li), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), bismuth (Bi), antimony (Sb), vanadium (V), indium (In), tantalum (Ta), molybdenum (Mo), tungsten (W), chromium (Cr), titanium (Ti), zirconium (Zr), hafnium (Hf), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), tungsten (Pr), neodymium (Nd), samarium (Sm), europium (Eu), thorium (Gd), tungsten (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thionium (Tm), ytterbium (Yb), argonium (Lu), copper (Cu), zinc (Zn), silver (Ag), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), silicon (Si), germanium (Ge), tin (Sn), and gallium (Ga). In cases where multiple of the elements are present, the total concentration is less than 5 at%, and the amount of dopant added is typically greater than 0.1 at%.

[0014] The target material 10 is formed into a disk shape, for example, and bonded (attached) to a back plate (cooling plate) (not shown) containing Cu, etc., via bonding materials such as In, Sn, and alloys containing these metals, thereby being used as a sputtering target. Of the two main surfaces of the target material 10, the surface different from the bonding surface with the cooling plate can be used as the surface exposed to plasma such as argon (Ar) during film formation, i.e., the sputtering surface 10s that releases atoms constituting the film.

[0015] When the target material 10 is disc-shaped, the diameter of the main surface of the target material 10 is preferably 75 mm or more, more preferably 80 mm or more, further preferably 90 mm or more, further preferably 100 mm or more, and especially preferably 200 mm or more. Regarding the area of ​​the main surface of the target material 10, the area of ​​the sputtering surface 10s is preferably 4500 mm² or more, more preferably 5000 mm² or more, further preferably 6000 mm² or more, further preferably 7500 mm² or more, and especially preferably 15000 mm² or more.

[0016] The target material 10 may also have a rectangular plate-like main surface. Regarding the length of the main surface of the target material 10 in the long side direction, it is preferably 80 mm or more, more preferably 100 mm or more, further preferably 120 mm or more, further preferably 150 mm or more, and particularly preferably 200 mm or more. Regarding the length of the main surface of the target material 10 in the short side direction, it is preferably 50 mm or more, more preferably 80 mm or more, and further preferably 100 mm or more. Regarding the area of ​​the main surface of the target material 10, it is preferably 4500 mm² or more, more preferably 5000 mm² or more, further preferably 6000 mm² or more, further preferably 7500 mm² or more, and particularly preferably 15000 mm² or more.

[0017] The thickness of the target material 10 is not particularly limited, but it is preferably 3.0 mm or more, more preferably 5.0 mm or more, and even more preferably 7.5 mm or more, and preferably 25 mm or less, more preferably 20 mm or less, and even more preferably 15 mm or less.

[0018] The backplate (cooling plate) is made of a conductive material, including metals or their alloys, such as Cu, Cu alloys, Al, Al alloys, Ti, and steel use stainless steel (SUS). Regarding the size of the cooling plate, there are no particular limitations as long as it can be used to bond and support the target material 10 and be mounted on the sputtering apparatus. Preferably, it is approximately the same size as the bonding surface of the target material 10, and more preferably, it is larger.

[0019] Details will be described later. When manufacturing the target material 10, various raw material powders containing K, Na, and Nb can be mixed and preferably calcined or pulverized to prepare raw material powder (hereinafter referred to as KNN raw material powder). From the viewpoint of powder homogeneity, the KNN raw material powder is preferably an oxide containing K, Na, and Nb in a solid solution state. Furthermore, in this sample, so-called spark plasma sintering (hereinafter also abbreviated as SPS) is performed. Spark plasma sintering is performed by applying mechanical pressure to a specified amount of KNN raw material powder to form a pressed powder, and then sintering the pressed powder by heating it with pulsed current.

[0020] During this sintering process, in the original sample, firstly, the pressed powder is pulsed-heated at a temperature of 450°C or higher under relatively low mechanical pressure to expel residual gases from the pressed powder (hereinafter, this process is also referred to as degassing or low-pressure SPS). Then, the degassed pressed powder is pulsed-heated under relatively high mechanical pressure (above the level required for the sintering reaction) to sinter the pressed powder (hereinafter, this process is also referred to as formal pressure SPS).

[0021] The target material 10 in this sample is sintered using a novel method of performing low-pressure SPS followed by formal pressure SPS. Therefore, it not only possesses a high relative density but also novel characteristics not exhibited in target materials sintered by formal pressure SPS without low-pressure SPS, or in target materials sintered using a so-called hot-pressing method. Specifically, the target material 10 in this sample possesses at least one of the features 1 to 13 described later. Consequently, the target material 10 in this sample further possesses at least one of the features 14 to 17 related to mechanical strength, etc. The relative density of the target material 10 in this sample is 80% or more, preferably 85% or more, more preferably 90% or more, more preferably 95% or more, and particularly preferably 98% or more over the entire sputtering surface area. Furthermore, the relative density (%) mentioned here refers to a value calculated by (measured density / theoretical density of KNN) × 100. Furthermore, the theoretical density of KNN is, for example, 4.52 g / cm³ in KNN with (K / (Na+K)) = 0.35.

[0022] The target material 10 in this sample is composed of grains with a number average particle size (hereinafter, sometimes referred to as Nd) observed in a cross-section parallel to the sputtering surface 10s, for example, of 0.10 μm or more and 20 μm or less, preferably 0.15 μm or more and 10 μm or less, more preferably 0.20 μm or more and 5.0 μm or less, and particularly preferably 0.25 μm or more and 1.5 μm or less. Furthermore, it is composed of grains with an area average particle size (hereinafter, sometimes referred to as Nv) observed in a cross-section parallel to the sputtering surface 10s, for example, of 0.10 μm or more and 20 μm or less, preferably 0.20 μm or more and 10 μm or less, more preferably 0.30 μm or more and 5.0 μm or less, and particularly preferably 0.45 μm or more and 2.0 μm or less. If the number average particle size and area average particle size of the target material 10 are within the aforementioned ranges, the mechanical strength of the target material 10 can be easily improved. The number-average particle size and area-average particle size of the target material 10 in this sample are described below. The number-average particle size and area-average particle size of the target material 10 in this sample are the same in either the case where heat treatment in an oxygen-containing atmosphere or atmosphere (hereinafter, sometimes referred to as oxidation treatment) is omitted in the manufacturing steps described below, or in the case where oxidation treatment is performed.

[0023] The following describes the various novel features that the target material 10 of this state can possess.

[0024] (Feature 1) One of the characteristics that the target material 10 can possess can be listed as follows: Among the multiple grains of alkali niobium oxide observed on the sputtered surface over 10 seconds, the number-average grain size Nd (μm) and area-average grain size Nv (μm) satisfy the relationship (Nv-Nd) / Nd≦2.1.

[0025] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0026] The number-average particle size Nd (μm) and area-average particle size Nv (μm) are preferably determined by analyzing the backscattered electron diffraction pattern (EBSD) image of the sputtered surface 10s of the target material 10. The crystal grain size determined by EBSD analysis is expressed as the diameter of a circle with the same area as the measured grain. The number-average particle size Nd (μm) can be the average particle size obtained by the number method in EBSD measurement. In the number method, the average area of ​​the grain is obtained by dividing the total area of ​​the analyzed object by the number of grains. The average particle size is the diameter of the area calculated by [measurement area (μm 2) / number of crystals] when the area is assumed to be a circle. When using the OIM crystal orientation analysis software manufactured by TSL Solutions Inc. in the analysis, if multiple voids, defects, etc. are found in the evaluation area of ​​the target material 10, areas with a Confidence Index (CI value) below the specified value defined by OIM are excluded. The crystal grain size is calculated based on the value of [(measured area - areas with CI value below the specified value) / number of crystals], thereby allowing for a more accurate calculation of the average grain size. On the other hand, the area-average grain size Nv (μm) can be obtained by using the area fraction method. In the area fraction method, the sum of the values ​​obtained by multiplying the proportion of the area of ​​each grain to the total area by the area values ​​of each grain is the average area of ​​the grain. The diameter of the calculated area, which is assumed to be a circle, is the average grain size. Furthermore, in EBSD analysis, by considering boundaries with a crystal orientation difference of more than a certain value, such as 15° or more, as grain boundaries, the number average grain size Nd (μm) and area average grain size Nv (μm) can be calculated.

[0027] In addition, the number-average grain size Nd (μm) and area-average grain size Nv (μm) can also be calculated using the following formulas. In the following formulas, di represents the observed grain size (μm), and ni represents the number of observed grains with a grain size di (μm). di is the diameter of a circle with an area equal to the area of ​​the observed grain, i.e., the circle equivalent diameter (μm).

[0028] Number average particle size Nd(μm) = Σ(di×ni) / Σn i Area-average particle size Nv (μm) = Σ(di 3×ni) / Σ(di 2×ni)

[0029] The area-average particle size Nv (μm) is a weighted average based on the particle area. When some grains grow larger than others, the area-average particle size Nv (μm) becomes larger than the number-average particle size Nd (μm). That is, the difference between the area-average particle size Nv (μm) and the number-average particle size Nd (μm) becomes larger, resulting in a larger value for (Nv-Nd) / Nd.

[0030] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is adopted during its manufacturing process. This method, compared to sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing, can suppress significant deviations in grain size, i.e., the situation where some grains grow larger than others. As a result, the aforementioned characteristics can be obtained in the target material 10 of this sample. Furthermore, in the case of sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing, the deviation in grain size becomes larger, and the aforementioned characteristics cannot be obtained.

[0031] (Feature 2) One of the characteristics that the target material 10 can possess can be listed as follows: Among the multiple grains observed on the sputtered surface over 10 seconds, the area-average grain size Nv (μm) and the area-average standard deviation Ns (μm) satisfy the relationship Ns / Nv≦0.76.

[0032] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0033] The area-average particle size Nv (μm) is calculated as described above. The area-average standard deviation Ns (μm) is calculated based on the distribution of the crystal grain size (the diameter when the crystal area is assumed to be a circle) of each crystal. If the grain size of each crystal obtained when calculating the area-average particle size is denoted as Di, it can be calculated using the following formula.

[0034] The standard deviation of the area mean, Ns(μm), is calculated as: 〔{Σ(Di-Nv)²} / Σnᵢ〕¹ / ²

[0035] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is adopted during its manufacturing process. This method, compared to sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing, can suppress significant deviations in grain size, i.e., the situation where some grains grow larger than others. As a result, the aforementioned characteristics can be obtained in the target material 10 of this sample. Furthermore, in the case of sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing, the deviation in grain size becomes larger, and the aforementioned characteristics cannot be obtained.

[0036] (Feature 3) One of the characteristics that the target material 10 can possess can be listed as follows: When the sputtered surface 10s is observed from the normal direction of the sputtered surface using the EBSD method, and the area of ​​the observation region in the sputtered surface 10s is set to 1, it has the following characteristics: <103> The area ratio A of grains in the 0-10° orientation <103> The area ratio A of the sputtered surface per unit area within 10 seconds. <103> It is above 0.061.

[0037] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0038] Furthermore, in this specification, the term "having" refers to... <103> Grains with an orientation of 0-10° refer to those observed when the crystal plane orientation of the sputtered surface is determined by EBSD method over 10 seconds. <103> The orientation difference (angle) between the orientation and the normal direction of the sputtered surface at 10s is within the range of 0° to 10°. Regarding the content described here, it can be considered that crystal planes with other orientations among the features described later, i.e., those with... <101> 0-10° <010> 0-10° <111> 0-10° <212> 0-10° <121> The same applies to crystal planes at any orientation between 0 and 10°.

[0039] In the target material 10 of this sample, the aforementioned characteristics are obtained by employing a novel method of performing low-pressure SPS followed by formal pressure SPS during its manufacturing process. Furthermore, the aforementioned characteristics cannot be obtained when performing formal pressure SPS without performing low-pressure SPS, or when using hot pressing for sintering.

[0040] (Feature 4) One of the characteristics that the target material 10 can possess can be listed as follows: The sputtered surface 10s was observed from the normal direction of the sputtered surface using the EBSD method, and the area of ​​the observation region in the sputtered surface 10s was set to 1. Will have <101> Grains with an orientation of 0-10°, possessing <010> Grains with an orientation of 0-10°, possessing <111> Grains with an orientation of 0-10°, possessing <103> Grains with an orientation of 0-10°, possessing <212> Grains with an orientation of 0-10°, and those with <121> Let A be the total area fraction of grains in the 0-10° orientation. Will have <103> Let A be the area ratio of grains in the 0-10° orientation. <103> hour, A <103> The ratio relative to A, i.e., A <103> / A is above 0.165.

[0041] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0042] In the target material 10 of this sample, the aforementioned characteristics are obtained by employing a novel method of performing low-pressure SPS followed by formal pressure SPS during its manufacturing process. Furthermore, the aforementioned characteristics cannot be obtained when performing formal pressure SPS without performing low-pressure SPS, or when using hot pressing for sintering.

[0043] (Feature 5) One of the characteristics that the target material 10 can possess can be listed as follows: The sputtered surface 10s was observed from the normal direction of the sputtered surface using the EBSD method, and the area of ​​the observation region in the sputtered surface 10s was set to 1. Will have <212> Grains with an orientation of 0-10°, and those with <121> Let A be the total area ratio of grains in the 0-10° orientation. <212> + <121> hour, A <212> + <121> The ratio relative to A, i.e., A <212> + <121> / A is below 0.580.

[0044] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0045] In the target material 10 of this sample, the aforementioned characteristics are obtained by employing a novel method of performing low-pressure SPS followed by formal pressure SPS during its manufacturing process. Furthermore, the aforementioned characteristics cannot be obtained when performing formal pressure SPS without performing low-pressure SPS, or when using hot pressing for sintering.

[0046] (Feature 6) One of the characteristics that the target material 10 can possess can be listed as follows: The sputtered surface 10s was observed from the normal direction of the sputtered surface using the EBSD method, and the area of ​​the observation region in the sputtered surface 10s was set to 1. Will have <101> Let A be the area ratio of grains in the 0-10° orientation. <101> hour, A <101> The ratio relative to A, i.e., A <101> / A is less than 0.130.

[0047] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0048] (Feature 7) One of the characteristics that the target material 10 can possess can be listed as follows: The total area ratio A, which is the total area ratio A in each unit area of ​​the sputtered surface 10s that was observed by the EBSD method, is 0.40 or more when the area of ​​the observed region in the sputtered surface 10s is set to 1.

[0049] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0050] In the target material 10 of this sample, the aforementioned characteristics are obtained by employing a novel method of performing low-pressure SPS followed by formal pressure SPS during its manufacturing process. Furthermore, the aforementioned characteristics cannot be obtained when performing formal pressure SPS without performing low-pressure SPS, or when using hot pressing for sintering.

[0051] (Feature 8) One of the characteristics that the target material 10 can possess can be listed as follows: The carbon concentration is below 200 ppm when the volume resistivity at 25℃ is less than 6.0×10 11Ω·cm.

[0052] This characteristic is one that becomes apparent when the oxidation process is omitted in the manufacturing steps described later. The carbon concentration in the target material 10 (or KNN sintered body) can be determined using the combustion-infrared absorption method.

[0053] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is employed during its manufacturing process. This allows for the desorption of carbon-containing gases and the like from the powder being sintered, compared to sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing. Furthermore, this characteristic cannot be obtained when sintering with formal pressure SPS without low-pressure SPS or when sintering using hot pressing.

[0054] (Feature 9) One of the characteristics that the target material 10 can possess can be listed as follows: The carbon concentration is below 90 ppm when the volume resistivity at 25℃ is above 6.0×10 11Ω·cm.

[0055] This feature is one that can be observed when an oxidation process is performed in the manufacturing steps described later.

[0056] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is employed during its manufacturing process. This allows for the desorption of carbon-containing gases and the like from the powder being sintered, compared to sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing. Furthermore, this characteristic cannot be obtained when sintering with formal pressure SPS without low-pressure SPS or when sintering using hot pressing.

[0057] (Feature 10) As one of the characteristics that the target material 10 can possess, it can be listed as follows: the carbon content, when the volume resistivity at 25°C is less than 6.0×10 11Ω·cm relative to the mass of the target material 10 (1 mg), is converted to a total of less than 5.0×10 -9 mol of carbon dioxide and carbon monoxide (i.e., less than 5.0×10 -9 mol / mg).

[0058] This feature is one that can be observed when the oxidation process is omitted in the manufacturing steps described later. The amount of carbon contained in the target material 10 (or KNN sintered body) can be determined using thermal desorption spectroscopy (TDS) analysis.

[0059] The carbon content contained in the target material 10 (or KNN sintered body) will not be entirely desorbed as carbon dioxide or carbon monoxide by temperature-induced desorption gas analysis; for example, it may sometimes remain in the target material 10 without desorption. Therefore, in this sample, the amount of carbon content contained in the target material 10 (or KNN sintered body) is defined as the total amount of carbon dioxide and carbon monoxide desorbed when the target material 10 (or KNN sintered body) is heated to 700°C to 1000°C.

[0060] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is employed during its manufacturing process. This allows for the desorption of carbon-containing gases and the like from the powder being sintered, compared to sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing. Furthermore, this characteristic cannot be obtained when sintering with formal pressure SPS without low-pressure SPS or when sintering using hot pressing.

[0061] (Feature 11) One of the characteristics that the target material 10 can possess can be listed as follows: Relative to the mass of the target material 10 (1 mg), the carbon content when the volume resistivity at 25°C is above 6.0 × 10¹¹ Ω·cm, converted to a total of carbon dioxide and carbon monoxide, is below 4.0 × 10⁻⁹ mol (i.e., below 4.0 × 10⁻⁹ mol / mg).

[0062] This feature is one that can be observed when an oxidation process is performed in the manufacturing steps described later.

[0063] The carbon content contained in the target material 10 (or KNN sintered body) will not be entirely desorbed as carbon dioxide or carbon monoxide by temperature-induced desorption gas analysis; for example, it may sometimes remain in the target material 10 without desorption. Therefore, in this sample, the amount of carbon content contained in the target material 10 (or KNN sintered body) is defined as the total amount of carbon dioxide and carbon monoxide desorbed when the target material 10 (or KNN sintered body) is heated to 700°C to 1000°C.

[0064] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is employed during its manufacturing process. This allows for the desorption of carbon-containing gases and the like from the powder being sintered, compared to sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing. Furthermore, this characteristic cannot be obtained when sintering with formal pressure SPS without low-pressure SPS or when sintering using hot pressing.

[0065] (Feature 12) One of the characteristics that the target material 10 can possess can be listed as follows: The ratio of the total area Sv of voids within the field of view to the observed area S in the sputtered surface over 10s, expressed as Sv / S×100 [%], or the ratio of Sv to the unit area of ​​the sputtered surface over 10s (hereinafter also referred to as the porosity), is 12.0% or less. Furthermore, the average diameter of the voids existing on the sputtered surface within 10 seconds is less than 0.60 μm.

[0066] This feature is one that can be observed when an oxidation process is performed in the manufacturing steps described later.

[0067] The term "void" refers to the voids or other openings that appear on the sputtering surface 10s due to pores or other defects within the target material 10. These voids can be observed as openings within the concave space on the sputtering surface 10s. The total area and average diameter of the voids present on the sputtering surface 10s can be calculated by analyzing an optical microscope image or a scanning electron microscope (SEM) image of the sputtering surface 10s using image analysis software. The total area of ​​the voids refers to the total planar area (cross-sectional area) of the openings. This can be calculated by analyzing the total area of ​​the void portions using image analysis. By calculating the ratio of the total area of ​​the void portions to the measured area, the ratio of the total area of ​​the voids can be determined. The average diameter of the voids refers to the average of the circular equivalent diameters (μm) of multiple voids observed within any field of view on the sputtering surface 10s. This value is substantially equal to the average diameter of the voids present on the sputtering surface 10s. The average diameter of the gap can be set as, for example, the equivalent diameter of a circle (50% area average diameter): the area of ​​each gap is calculated by image analysis, and all such areas are added together to obtain the total area. The equivalent diameter of a circle is calculated based on the area when the cumulative area relative to the total area becomes 50%.

[0068] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is adopted during its manufacturing process. This method, compared to sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing, can suppress the appearance of voids on the sputtered surface within 10 seconds and can also minimize voids, thereby obtaining the aforementioned characteristics. Furthermore, in the case of sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing, it is impossible to obtain at least one of the aforementioned characteristics regarding porosity or the average diameter of voids.

[0069] (Feature 13) One of the characteristics that the target material 10 can possess can be listed as follows: The maximum diameter of the voids existing on the sputtered surface within 10 seconds is less than 1.0 μm.

[0070] This feature is one that can be observed when an oxidation process is performed in the manufacturing steps described later.

[0071] The maximum diameter of the void refers to the circular equivalent diameter (μm) of the void with the largest size among multiple voids observed in any field of view within 10 seconds on the sputtered surface. This value is substantially equal to the maximum diameter of the void present on the sputtered surface within 10 seconds. In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is adopted during its manufacturing process. This allows for void miniaturization compared to sintering with formal pressure SPS without low-pressure SPS or sintering using hot pressing, thereby obtaining the aforementioned characteristic. Furthermore, the aforementioned characteristic cannot be obtained when sintering with formal pressure SPS without low-pressure SPS or when sintering using hot pressing.

[0072] (Feature 14) One of the characteristics that the target material 10 can possess can be listed as follows: When the volume resistivity at 25℃ is less than 6.0×10 11Ω·cm, the Vickers hardness is above 460 and the flexural strength is above 90 MPa.

[0073] This characteristic is one that becomes apparent when the oxidation process is omitted in the manufacturing steps described later. Furthermore, the Vickers hardness (Hv) of the target material 10 (or the KNN sintered body) can be measured according to Japanese Industrial Standards (JIS) R1610:2003 using a Vickers hardness tester, for example, by the method described in the examples. Additionally, the flexural strength of the target material 10 (or the KNN sintered body) can be determined according to JIS R 1610:2008 using a three-point bending test, for example, by the method described in the examples.

[0074] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is adopted during its manufacturing process, thereby obtaining at least one of the characteristics 1 to 13. As a result, the Vickers hardness of the target material 10 can be increased while its flexural strength is also increased. Furthermore, when sintering is performed by formal pressure SPS without performing low-pressure SPS, or when sintering is performed by hot pressing, the characteristics 1 to 13 will not be exhibited. When the oxidation treatment is omitted (when the volume resistivity at 25°C is less than 6.0 × 10¹¹ Ω·cm), the characteristics regarding Vickers hardness or flexural strength cannot be obtained.

[0075] (Feature 15) One of the characteristics that the target material 10 can possess can be listed as follows: When the volume resistivity at 25℃ is above 6.0×10 11Ω·cm, the Vickers hardness is above 250, and the flexural strength is above 90 MPa.

[0076] This feature is one that can be observed when an oxidation process is performed in the manufacturing steps described later.

[0077] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS during its manufacturing process is adopted, thereby obtaining at least one of the aforementioned characteristics 1 to 13. As a result, the Vickers hardness of the target material 10 can be increased while its flexural strength is also improved. Furthermore, when sintering is performed by formal pressure SPS without performing low-pressure SPS, or when sintering is performed by hot pressing, the aforementioned characteristics 1 to 13 will not be exhibited. When oxidation treatment is performed (with a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C), the aforementioned characteristics regarding Vickers hardness or flexural strength cannot be obtained.

[0078] (Feature 16) One of the characteristics that the target material 10 can possess can be listed as follows: The Vickers hardness after heat treatment at 900°C for 5 hours in the atmosphere remains more than 50% of the Vickers hardness before heat treatment.

[0079] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0080] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal pressure SPS is adopted during its manufacturing process. This allows at least one of the characteristics 1 to 13 to be obtained, resulting in the acquisition of the aforementioned characteristics regarding Vickers hardness before and after heat treatment. Furthermore, if formal pressure SPS is performed without low-pressure SPS for sintering, or if hot pressing is used for sintering, characteristics 1 to 13 will not be exhibited, and these characteristics cannot be obtained.

[0081] (Feature 17) One of the characteristics that the target material 10 can possess can be listed as follows: The relative density after heat treatment at 900°C for 5 hours in the atmosphere remains more than 95% of the relative density before heat treatment.

[0082] This feature is present in either the case where oxidation treatment is omitted or the case where oxidation treatment is performed in the manufacturing steps described later.

[0083] In the target material 10 of this sample, a novel method of performing low-pressure SPS followed by formal-pressure SPS is adopted during its manufacturing process. This allows at least one of the characteristics 1 to 13 to be obtained, and consequently, the characteristics are obtained regarding the relative density before and after heat treatment. Furthermore, if formal-pressure SPS is performed without low-pressure SPS for sintering, or if hot pressing is used for sintering, characteristics 1 to 13 will not be exhibited, and these characteristics cannot be obtained.

[0084] (2) Manufacturing method of target material A preferred embodiment of the manufacturing method of the target material 10 in this sample will be described in detail with reference to Figures 2 and 3.

[0085] (Prepare the starting material powder) First, prepare powders containing K, Na, and Nb, such as potassium carbonate (K₂CO₃) powder, sodium carbonate (Na₂CO₃) powder, and niobium pentoxide (Nb₂O₅) powder as starting raw material powders.

[0086] Furthermore, the term "powder containing K compounds" mentioned here refers to powders whose main component is a K compound. This includes powders composed solely of K compounds, as well as powders containing K compounds as the main component and other compounds. Similarly, "powder containing Na compounds" refers to powders whose main component is a Na compound. This includes powders composed solely of Na compounds, as well as powders containing Na compounds as the main component and other compounds. "Powder containing Nb compounds" refers to powders whose main component is an Nb compound. This includes powders composed solely of Nb compounds, as well as powders containing Nb compounds as the main component and other compounds. The term "K compound" refers to at least one selected from the group consisting of K oxides, K complex oxides, and K compounds that become oxides upon heating. Examples include carbonates as described above, and oxalates, etc. The term "Na compound" refers to at least one selected from the group consisting of Na oxides, Na complex oxides, and Na compounds that become oxides upon heating. Examples include carbonates as described above, as well as oxalates. Similarly, the term "Nb compound" refers to at least one selected from the group consisting of Nb oxides, Nb complex oxides, and Nb compounds that become oxides upon heating. Examples include niobium pentoxide as described above.

[0087] Additionally, as needed, prepare powders containing at least one doping element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga, such as powders of the element as a monomer, oxide powders containing the element, composite oxide powders containing the element, and powders of compounds containing the element (e.g., carbonates, oxalates) that become oxides by heating, as starting material powders.

[0088] Furthermore, regarding the average particle size of these starting material powders, for example, the median particle size D50 is preferably less than 1 mm. If necessary, it is preferable to pre-crush the starting material powders before weighing.

[0089] (weighing, mixing) Next, the starting material powders are weighed, and the mixing ratio of the starting material powders is adjusted so that the composition of the final target material 10 is the desired composition. Weighing can be carried out in the atmosphere, but it is preferable to carry out it in an atmosphere with low humidity, such as an inert gas atmosphere, a vacuum atmosphere, or a dry air atmosphere. In addition, it is preferable to carry out it after the starting material powders are fully dried. Then, the weighed starting material powders are dry-mixed using mixers such as Henschel mixers, blenders, belt mixers, super mixers, Nauta mixers, high-intensity mixers, and automatic mortars.

[0090] (Single firing, coarse grinding) The obtained mixed powder is calcined once using an electric furnace or similar oxidizing atmosphere, such as under atmospheric or oxygen conditions, to obtain a calcined product containing K, Na, and Nb. Preferably, the mixed powder undergoes a solid-phase reaction during the single calcination to obtain a calcined product in which K, Na, and Nb are in a solid solution state. Then, the obtained calcined product is coarsely pulverized using a grinding unit such as a ball mill, bead mill, vibratory mill, grinder, jet mill, atomizer, or cutting mill to obtain calcined powder (hereinafter referred to as KNN calcined powder). By achieving a solid solution state for K, Na, and Nb through a single calcination, KNN calcined powder (hereinafter referred to as KNN solid solution powder) in which K, Na, and Nb are in a solid solution state can be obtained.

[0091] The heating temperature for a single firing is preferably 500°C or higher, more preferably 550°C or higher, even more preferably 600°C or higher, and preferably 750°C or lower, even more preferably 700°C or lower. If the heating temperature is above the lower limit, it is easier to obtain KNN solid solution powder in a solid solution state of K, Na, and Nb, and also easier to obtain calcined powder with high homogeneity. If the heating temperature is below the upper limit, it is easier to increase the Brunauer-Emmett-Teller (BET) specific surface area of ​​both the calcined KNN powder and the KNN solid solution powder, and easier to obtain calcined powder with high sinterability.

[0092] There is no particular limit to the firing time, but it is better to be more than 3 hours and less than 20 hours, more preferably more than 4 hours and less than 15 hours, and even better to be more than 5 hours and less than 10 hours.

[0093] (Bake, coarsely grind) The obtained KNN calcined powder (or KNN solid solution powder) is further calcined in an oxidizing atmosphere such as atmospheric or oxygen atmosphere, and then coarsely pulverized using grinding units such as ball mills, bead mills, vibratory mills, grinders, jet mills, and atomizers to obtain KNN calcined powder. This calcination process removes impurities such as moisture, carbon, and chlorine from the KNN calcined powder, resulting in high-purity KNN calcined powder.

[0094] The heating temperature during calcination is preferably above 500°C, more preferably above 600°C, further preferably above 650°C, particularly preferably above 700°C, and preferably below 1150°C, more preferably below 1100°C, and further preferably below 1000°C. If the heating temperature is above the lower limit, it is easy to obtain high-purity KNN calcined powder; if the heating temperature is below the upper limit, it is easy to obtain KNN raw material powder with a large BET specific surface area and high sintering properties.

[0095] There is no particular limitation on the heating time during simmering, but it is preferable to be more than 3 hours and less than 50 hours, more preferably more than 3.5 hours and less than 30 hours, even more preferably more than 4 hours and less than 20 hours, and most preferably more than 5 hours and less than 12 hours.

[0096] In the calcination process, from the viewpoint of easily removing impurities, multi-stage heat treatment can also be carried out at different heating temperatures.

[0097] (Fine grinding) The KNN calcined powder obtained by coarse grinding is preferably further pulverized using a ball mill, bead mill, vibratory mill, grinder, atomizer, and jet mill, and dried as needed after pulverization, thereby obtaining KNN raw material powder with specified specifications (specific surface area, impurity concentration, etc.).

[0098] For example, when using a jet mill to pulverize calcined powder, the processing speed is 1.0 kg / h or more and 8.0 kg / h or less, preferably 1.2 kg / h or more and 6.0 kg / h or less, and more preferably 1.5 kg / h or more and 3.0 kg / h or less. Furthermore, the induction pressure is 0.1 MPa or more and 2.0 MPa or less, preferably 0.5 MPa or more and 1.8 MPa or less, more preferably 1.0 MPa or more and 1.7 MPa or less, and the pulverization pressure is 0.1 MPa or more and 2.0 MPa or less, preferably 0.5 MPa or more and 1.8 MPa or less, and more preferably 1.0 MPa or more and 1.7 MPa or less. If the calcined powder is pulverized under the aforementioned conditions, it is easy to obtain raw material powder with a large BET specific surface area and high sintering properties.

[0099] Through the above steps, KNN raw material powder for SPS sintering of this sample can be obtained. The BET specific surface area of ​​the KNN raw material powder is preferably 1.0 m² / g or more, more preferably 2.0 m² / g or more, even more preferably 2.5 m² / g or more, particularly preferably 3.0 m² / g or more, and preferably 11 m² / g or less, even more preferably 10 m² / g or less, even more preferably 8.0 m² / g or less, even more preferably 7.0 m² / g or less, and particularly preferably 6.0 m² / g or less. If the BET specific surface area of ​​the KNN raw material powder is above the aforementioned lower limit, the sinterability is improved, and a high-density KNN sintered body is easily obtained. Furthermore, if the BET specific surface area of ​​the KNN raw material powder is below the aforementioned upper limit, the amount of gaseous components (e.g., atmospheric gases, carbon dioxide, carbon monoxide, methane, etc.) or moisture adsorbed onto the manufactured raw material powder can be reduced, making it easier to obtain KNN sintered bodies with fewer impurities or pores. The BET specific surface area of ​​the KNN raw material powder can be measured using a gas adsorption device and determined by the method described in the examples. If necessary, the obtained KNN raw material powder can be dried, for example, by heating it at 180°C to 200°C before use.

[0100] In addition, the carbon concentration in the KNN raw material powder is preferably below 250 ppm, and more preferably below 200 ppm.

[0101] The KNN raw material powder used for SPS sintering of this sample can also be obtained by mixing KNbO3 powder and NaNbO3 powder obtained by hydrothermal synthesis. The hydrothermal synthesis method involves reacting potassium hydroxide or sodium hydroxide aqueous solution with Nb2O5 powder as the starting material powder in hot water under high temperature and pressure. The reactants obtained from the hydrothermal synthesis are subjected to processes such as solid-liquid separation, washing, and drying to obtain oxide powders (KNbO3 powder and NaNbO3 powder). The obtained KNbO3 powder and NaNbO3 powder are then mixed in a specified ratio to obtain the KNN raw material powder.

[0102] From the viewpoint of promoting the reaction in hydrothermal synthesis, the temperature of the hot water is preferably above 150°C, more preferably above 180°C, even more preferably above 200°C, and preferably below 350°C, even more preferably below 300°C, even more preferably below 250°C; the pressure of the hot water is preferably above 0.1 MPa, more preferably above 0.2 MPa, even more preferably above 0.5 MPa, even more preferably above 1.0 MPa, particularly preferably above 1.5 MPa, and preferably below 10 MPa, even more preferably below 5 MPa, even more preferably below 3 MPa.

[0103] By using hydrothermal synthesis to prepare KNN raw material powder, the carbon concentration in the KNN raw material powder can be further reduced. As a result, by using KNN raw material powder prepared by hydrothermal synthesis, the carbon concentration of the KNN sintered body can be further reduced.

[0104] Furthermore, by subjecting the KNN raw material powder obtained through hydrothermal synthesis to the aforementioned calcination or other treatments, KNN raw material powder containing dissolved K, Na, and Nb (KNN solid solution powder) can be obtained. Alternatively, by pre-mixing potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, and Nb₂O₅ powder and reacting the mixture in hot water under high temperature and pressure, KNN raw material powder containing dissolved K, Na, and Nb can also be obtained. Furthermore, the aforementioned calcination or pulverization treatments can be applied to KNN raw material powder or KNN solid solution powder prepared through hydrothermal synthesis to achieve the desired BET specific surface area.

[0105] Furthermore, the processes of primary firing, coarse crushing, calcination, coarse crushing, and jet mill crushing can be performed partially or completely repeatedly as needed; additionally, any of these processes can be omitted. Furthermore, after these processes are completed, or during the intervals between processes, additional screening processes can be performed. The mixing or crushing unit is not limited to the examples shown above and can be widely adopted from other crushing units. Furthermore, the conditions at this time can be widely selected corresponding to the purpose of obtaining the aforementioned specifications.

[0106] Next, a preferred embodiment of the low-pressure SPS and formal-pressure SPS steps will be described with reference to FIG3. FIG3 is a schematic structural diagram of the sintering apparatus 100 used in these steps. The sintering apparatus 100 includes a chamber 101, a mold 102, a punch 103, a punch 104, a pressurizing device 105, a pressurizing device 106, a vacuum pump 110, a pressure gauge 111, a pulse energizing device 120, etc.

[0107] (Low-pressure SPS) First, a specified amount of KNN raw material powder of the stated specifications is filled into a cylindrical mold (sintering mold) 102. Next, the mold 102 filled with KNN raw material powder is housed within a chamber 101 and positioned between a pair of upper and lower punches 103 and 104. Then, while using a vacuum pump 110 to vent the vacuum from the chamber 101, the pressure within the chamber 101 is monitored using a pressure gauge 111. The mold 102 and the punches 103 and 104 can be made of any conductive material, but are preferably made of carbon materials such as graphite.

[0108] After the desired pressure is achieved within chamber 101, pressurizing devices 105 and 106 are activated to apply mechanical pressure to the KNN raw material powder filled in mold 102 via punches 103 and 104. Simultaneously, pulse energizing device 120 is used to begin heating the KNN raw material powder using pulse energizing. By initiating pulse energizing, the temperature of the pressed powder formed by pressurizing the KNN raw material powder gradually rises from an initial temperature of approximately room temperature (25°C) to the specified degassing temperature shown below.

[0109] The degassing temperature is above 450°C, which can be set to the same level as the sintering temperature in the formal pressurized SPS shown below, but the applied mechanical pressure (degassing pressure) is much lower than the mechanical pressure (sintering pressure) in the formal pressurized SPS. Therefore, in low-pressure SPS, while the sintering reaction of the KNN raw material powder in the pressed powder proceeds slowly, degassing in the self-pressurized powder is easily generated by the simultaneous heating.

[0110] Regarding the mechanical pressure in this low-pressure SPS step, as long as there is stable power supply in the SPS device, it is acceptable. However, from the viewpoint of easily expelling residual gas from the self-pressurized powder, it is preferably 1 MPa or more, more preferably 5 MPa or more, even more preferably 7 MPa or more, even more preferably 8 MPa or more, and preferably 15 MPa or less, even more preferably 12 MPa or less, even more preferably 10 MPa or less.

[0111] Furthermore, the degassing temperature during the low-pressure SPS step is preferably 500°C or higher, more preferably 600°C or higher, even more preferably 700°C or higher, even more preferably 800°C or higher, particularly preferably 900°C or higher, and preferably 1200°C or lower, even more preferably 1100°C or lower. If the degassing temperature during the low-pressure SPS step is within the aforementioned range, residual gases are easily discharged, and sintered bodies with high mechanical strength are easily obtained.

[0112] The heating time at the degassing temperature is not particularly limited. It can be set to heat at a temperature above the degassing temperature for a certain period of time by setting a sufficient heating time, or it can be maintained at the degassing temperature for a certain period of time. When maintaining the state at the degassing temperature, the holding time is preferably 5 minutes or more, more preferably 10 minutes or more, more preferably 20 minutes or more, preferably less than 10 hours, more preferably less than 5 hours, more preferably less than 3 hours, more preferably less than 60 minutes, particularly preferably less than 50 minutes, and especially more preferably less than 40 minutes.

[0113] Furthermore, in low-pressure SPS, heating is achieved through pulsed current, which allows for the efficient desorption of residual gases (e.g., carbon monoxide, carbon dioxide, moisture, and other chlorine-based impurities) adsorbed on the surface of the grains, via electromagnetic energy, Joule heating, and interparticle discharge plasma. These gases are then released from the pressed powder. Low-pressure SPS also inhibits excessive grain growth while generating the KNN raw material powder and efficiently degassing the pressed powder, thus reducing voids and densifying the powder. In other words, it reduces the remaining space around the grains in the pressed powder, resulting in a more densely condensed state of the grains.

[0114] When the gas is released from the self-pressurized powder, the pressure inside chamber 101 rises, but when the gas release from the self-pressurized powder is complete, the pressure inside chamber 101 drops again. Therefore, by monitoring this pressure change using pressure gauge 111, the timing of the low-pressure SPS can be determined.

[0115] Other conditions that can be cited as examples for performing low-pressure SPS are as follows. Powder pressing temperature (initial temperature): room temperature (25℃) ~ 80℃ Atmospheric pressure (pressure within the chamber): below 10 Pa

[0116] (Formal SPS pressurization) After the gas in the self-pressed powder is released, while continuing to vent the chamber 101 and continuing to heat it using pulse energization via pulse energizing device 120, the mechanical pressure applied to the pressed powder is made greater than the mechanical pressure in the low-pressure SPS. The mechanical pressure applied at this time (sintering pressure) is set to a pressure greater than or equal to the pressure required for the sintering reaction of the pressed powder to proceed fully.

[0117] From the viewpoint of obtaining a sintered body with high density and strong crack resistance, the mechanical pressure in the formal pressurized SPS step is preferably 25 MPa or more, more preferably 30 MPa or more, even more preferably 35 MPa or more, and preferably 70 MPa or less, even more preferably 60 MPa or less, even more preferably 50 MPa or less.

[0118] In addition, from the viewpoint of obtaining a sintered body with high density and strong crack resistance, the heating temperature in the formal pressure SPS step is preferably 700°C or higher, more preferably 750°C or higher, even more preferably 800°C or higher, even more preferably 850°C or higher, particularly preferably 900°C or higher, and preferably 1100°C or lower, even more preferably 1000°C or lower, even more preferably 980°C or lower, and particularly preferably 960°C or lower.

[0119] The heating time at the stated heating temperature is not particularly limited. It can be set to heat at a temperature above the stated heating temperature for a certain period by sufficiently setting the heating time, or it can be maintained at the stated heating temperature for a certain period. When maintaining the heating temperature for a certain period, the maintenance time is preferably 10 minutes or more, more preferably 15 minutes or more, even more preferably 20 minutes or more, and preferably 240 minutes or less, even more preferably 180 minutes or less, even more preferably 120 minutes or less.

[0120] By performing this process to sinter the pressed powder, a high-density sintered body can be obtained. In the sintering process using SPS, compared with the sintering process using hot pressing, sintering can be carried out uniformly at a low sintering temperature and in a short time. This can suppress grain growth in the sintered body and also densify the sintered body.

[0121] Other conditions that can be cited as examples when performing formal pressurized SPS are as follows. Atmospheric pressure (pressure within the chamber): below 10 Pa

[0122] The above describes an embodiment of low-pressure SPS and formally pressurized SPS, but the SPS sintering can also be carried out in an inert atmosphere, such as an atmosphere containing inert gases such as nitrogen, argon, helium, and hydrogen.

[0123] (Oxidation treatment) Furthermore, during low-pressure SPS or full-pressure SPS, impurities such as carbon components may desorb from the compressed powder. Additionally, oxygen may sometimes desorb from the oxide sintered body, resulting in a slight decrease in the insulation of the final target material 10. Therefore, if necessary, after full-pressure SPS, the oxide sintered body can be heat-treated in an oxygen-containing atmosphere to increase its resistivity, thereby restoring its insulation. Furthermore, this oxidation treatment can further reduce impurities remaining after SPS sintering.

[0124] The oxidation treatment is carried out in an oxidizing atmosphere, such as air or an oxygen-containing atmosphere, at a heating temperature of 500°C or higher and 1100°C, preferably 700°C or higher and 1050°C, more preferably 800°C or higher and 1020°C, and even more preferably 850°C or higher and 1000°C. The heating time is 1 hour or higher and 40 hours or lower, preferably 2 hours or higher and 20 hours or lower, more preferably 3 hours or higher and 10 hours or lower, and even more preferably 4 hours or higher and 7 hours or lower.

[0125] Furthermore, the oxidation process can be omitted if necessary. When the oxidation process is omitted, the final target material 10 has a volume resistivity of less than 6.0 × 10¹¹ Ω·cm at 25°C. Conversely, when the oxidation process is performed, the final target material 10 has a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C.

[0126] (Fine finishing / Jointing with the back panel) Then, as needed, the sintered body is ground into a disc shape, for example, having an area of ​​4500 mm² or more and a thickness of 3 mm or more, or the surface is ground to adjust the surface condition, thereby obtaining the target material 10 in this sample. The target material 10 is bonded to a backing plate containing Cu or the like via bonding materials such as In, Sn, and alloys containing these metals, thereby being used as a sputtering target.

[0127] (3) Effect By using this state, one or more of the effects shown below can be obtained.

[0128] (a) The target material 10 in this sample is sintered by a novel method of performing formal pressure SPS after performing low-pressure SPS, and thus possesses at least one of the features 1 to 13.

[0129] As a result, the target material 10 in this sample further possesses at least one of the features 14 to 17 related to mechanical strength, etc.

[0130] Furthermore, the target material 10, which possesses the properties shown in features 14 and 15, is less prone to cracks or gaps during machining processes such as grinding when manufacturing the target material 10, and also during sputtering film formation using the target material 10. In addition, abnormal discharges caused by cracks or gaps are less likely to occur during sputtering film formation, thus suppressing changes in composition or degradation of properties in the obtained sputtered film (piezoelectric thin film).

[0131] Furthermore, the target material 10 with the properties shown in features 16 and 17 does not easily change in Vickers hardness or relative density before and after heat treatment, so the target material 10 can be used stably in high-temperature sputtering film forming processes.

[0132] Furthermore, when sintering is performed using formal pressure SPS without low-pressure SPS, or when sintering is performed using hot pressing, features 1 to 13 will not appear. As a result, none of the features shown in features 14 to 17 can be obtained.

[0133] (b) By appropriately selecting the manufacturing conditions of the target material 10 within the range of the conditions described, it is possible not only to make (Nv-Nd) / Nd 2.1 or less, but also to make (Nv-Nd) / Nd preferably 1.5 or less, more preferably 1.0 or less, even more preferably 0.80 or less, even more preferably 0.70 or less, particularly preferably 0.60 or less, especially more preferably 0.50 or less, and even more preferably 0.44 or less.

[0134] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned condition range, it is possible not only to make Ns / Nv 0.76 or less, but also to make Ns / Nv preferably 0.70 or less, more preferably 0.60 or less, even more preferably 0.55 or less, even more preferably 0.50 or less, and especially preferably 0.47 or less.

[0135] The results show that the mechanical strength properties of the target material 10 can be further improved.

[0136] Specifically, even without oxidation treatment (where the volume resistivity at 25°C is less than 6.0 × 10¹¹ Ω·cm), the Vickers hardness can be achieved to be 460 or higher, preferably 470 or higher, more preferably 480 or higher, even more preferably 490 or higher, even more preferably 500 or higher, and particularly preferably 510 or higher. Furthermore, the flexural strength can be achieved to be 90 MPa or higher, preferably 100 MPa or higher, even more preferably 110 MPa or higher, even more preferably 120 MPa or higher, and even more preferably 130 MPa or higher.

[0137] Furthermore, when oxidation treatment is performed (with a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C), not only can the Vickers hardness be 210 or higher, but it can also be preferably 250 or higher, more preferably 300 or higher, even more preferably 350 or higher, even more preferably 400 or higher, particularly preferably 450 or higher, and especially more preferably 500 or higher. In addition, not only can the flexural strength be 90 MPa or higher, but it can also be preferably 100 MPa or higher, more preferably 110 MPa or higher, even more preferably 120 MPa or higher, and even more preferably 130 MPa or higher.

[0138] Furthermore, these results indicate that the Vickers hardness or relative density of the target material 10 can be further improved before and after heat treatment.

[0139] Specifically, it can not only make the Vickers hardness after heat treatment at 900°C for 5 hours in the atmosphere more than 50% higher than the Vickers hardness before heat treatment, but also preferably more than 70%, more preferably more than 90%, more preferably more than 95%, and more preferably more than 100%.

[0140] Furthermore, it is possible not only to make the relative density after heat treatment in the atmosphere at 900°C for 5 hours more than 95% of the relative density before heat treatment, but also to make it preferably more than 97%, more preferably more than 99%, and more preferably more than 100%.

[0141] Furthermore, there is no particular limitation on the lower limit value of (Nv-Nd) / Nd. However, when the relative density of the target material 10 exceeds 95%, it is preferable to make (Nv-Nd) / Nd 0.10 or higher, preferably 0.20 or higher, more preferably 0.30 or higher, even more preferably 0.35 or higher, and especially preferably 0.40 or higher, so as to more effectively suppress cracks and notches in the target material 10.

[0142] Furthermore, there are no particular restrictions on the lower limit value of Ns / Nv. However, when the relative density of the target material 10 exceeds 95%, it is preferable to make Ns / Nv 0.10 or higher, preferably 0.20 or higher, more preferably 0.30 or higher, even more preferably 0.35 or higher, and especially preferably 0.40 or higher, so as to more effectively suppress cracks and notches in the target material 10.

[0143] (c) By appropriately selecting the manufacturing conditions of the target material 10 within the range of conditions described above, it is possible not only to enable A <103> It becomes above 0.061, and can make A <103> The better value is 0.065 or higher, the better value is 0.070 or higher, the even better value is 0.075 or higher, and the best value is 0.080 or higher.

[0144] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned range of conditions, it is possible not only to enable A <103> / A becomes 0.165 or higher, and can make A <103> / A is preferably 0.170 or higher, better is 0.172 or higher, even better is 0.175 or higher, even better is 0.178 or higher, and best is 0.180 or higher.

[0145] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned range of conditions, it is possible not only to enable A <212> + <121> / A becomes below 0.580, and is able to make A <212> + <121> / A is preferably below 0.550, better is below 0.530, even better is below 0.520, and most preferably is below 0.500.

[0146] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned range of conditions, it is possible not only to enable A <101> / A is less than 0.130, and it can make A <101> / A is preferably below 0.120, more preferably below 0.115, and even better below 0.110.

[0147] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned range of conditions, it is possible not only to make A 0.40 or higher, but also to make A preferably 0.42 or higher, more preferably 0.43 or higher, even more preferably 0.45 or higher, and especially preferably 0.46 or higher.

[0148] The results are that the mechanical strength properties of the target material 10 can be further improved, and cracks or gaps in the target material 10 can be prevented even when sputtering at high power, thereby improving the productivity of thin film manufacturing using sputtering.

[0149] Specifically, even without oxidation treatment (where the volume resistivity at 25°C is less than 6.0 × 10¹¹ Ω·cm), the Vickers hardness can be achieved to be 460 or higher, preferably 470 or higher, more preferably 480 or higher, even more preferably 490 or higher, even more preferably 500 or higher, and particularly preferably 510 or higher. Furthermore, the flexural strength can be achieved to be 90 MPa or higher, preferably 100 MPa or higher, even more preferably 110 MPa or higher, even more preferably 120 MPa or higher, and even more preferably 130 MPa or higher.

[0150] Furthermore, when oxidation treatment is performed (with a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C), not only can the Vickers hardness be 210 or higher, but it can also be preferably 250 or higher, more preferably 300 or higher, even more preferably 350 or higher, even more preferably 400 or higher, particularly preferably 450 or higher, and especially more preferably 500 or higher. In addition, not only can the flexural strength be 90 MPa or higher, but it can also be preferably 100 MPa or higher, more preferably 110 MPa or higher, even more preferably 120 MPa or higher, and even more preferably 130 MPa or higher.

[0151] Furthermore, these results indicate that the Vickers hardness or relative density of the target material 10 can be further improved before and after heat treatment.

[0152] Specifically, it can not only make the Vickers hardness after heat treatment at 900°C for 5 hours in the atmosphere more than 50% higher than the Vickers hardness before heat treatment, but also preferably more than 70%, more preferably more than 90%, more preferably more than 95%, and more preferably more than 100%.

[0153] Furthermore, it is possible not only to make the relative density after heat treatment in the atmosphere at 900°C for 5 hours more than 95% of the relative density before heat treatment, but also to make it preferably more than 97%, more preferably more than 99%, and more preferably more than 100%.

[0154] Furthermore, regarding A <103> There is no particular limit to the upper limit. Specifically, in cases where the relative density of the target material 10 exceeds 95%, by making A... <103> The optimal concentration is 0.300 or less, preferably 0.250 or less, even better 0.200 or less, further preferably 0.150 or less, even better 0.120 or less, particularly preferably 0.110 or less, and especially better 0.100 or less, which can more effectively suppress cracks and notches in the target material 10.

[0155] Regarding A <103> There is no particular limit to the upper limit of / A. However, in cases where the relative density of the target material 10 exceeds 95%, etc., by making A... <103> / A is 0.60 or less, preferably 0.45 or less, more preferably 0.35 or less, even better 0.30 or less, even better 0.25 or less, particularly better 0.24 or less, and especially better 0.20 or less, which can more effectively suppress cracks and notches in the target material 10, thus achieving better results.

[0156] In addition, regarding A <212> + <121> There is no particular limitation on the lower limit of / A. Specifically, in cases where the relative density of the target material 10 exceeds 95%, etc., by making A... <212> + <121> / A is 0.20 or higher, preferably 0.30 or higher, even better 0.35 or higher, further preferably 0.40 or higher, even better 0.43 or higher, particularly better 0.45 or higher, and especially better 0.47 or higher, which can more effectively suppress cracks and notches in the target material 10, thus achieving better results.

[0157] In addition, regarding A <101> There is no particular limitation on the lower limit of / A. Specifically, in cases where the relative density of the target material 10 exceeds 95%, etc., by making A... <101> / A is 0.050 or higher, preferably 0.060 or higher, even better 0.070 or higher, further preferably 0.080 or higher, and even better 0.100 or higher, which can more effectively suppress cracks and notches in the target material 10, thus achieving better results.

[0158] Furthermore, there is no particular limitation on the upper limit of A. In cases where the relative density of the target material 10 exceeds 95%, it is preferable to make A 0.90 or less, preferably 0.75 or less, more preferably 0.60 or less, even more preferably 0.55 or less, and even more preferably 0.50 or less, so as to more effectively suppress cracks and notches in the target material 10.

[0159] (d) By appropriately selecting the manufacturing conditions of the target material 10 within the range of conditions described above, even without oxidation treatment (where the volume resistivity at 25°C is less than 6.0 × 10¹¹ Ω·cm), it is possible not only to make the carbon concentration less than 200 ppm, but also to make the carbon concentration preferably less than 180 ppm, more preferably less than 150 ppm, even more preferably less than 130 ppm, even more preferably less than 100 ppm, particularly preferably less than 80 ppm, and especially more preferably less than 60 ppm.

[0160] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned range, when an oxidation treatment is performed (with a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C), it is possible not only to achieve a carbon concentration of 90 ppm or less, but also to achieve a carbon concentration of preferably 80 ppm or less, more preferably 50 ppm or less, even more preferably 40 ppm or less, even more preferably 30 ppm or less, and especially preferably 20 ppm or less.

[0161] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned range, even without oxidation treatment (where the volume resistivity at 25°C is less than 6.0 × 10⁻⁹ Ω·cm), it is possible not only to make the carbon content 5.0 × 10⁻⁹ mol / mg or less, but also to make the carbon content preferably 4.5 × 10⁻⁹ mol / mg or less, more preferably 4.0 × 10⁻⁹ mol / mg or less, further preferably 3.5 × 10⁻⁹ mol / mg or less, further preferably 3.0 × 10⁻⁹ mol / mg or less, and especially preferably 2.5 × 10⁻⁹ mol / mg or less.

[0162] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned range, under the condition of performing oxidation treatment (with a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C), it is possible not only to make the carbon content 4.0 × 10⁻⁹ mol / mg or less, but also to make the carbon content preferably 3.0 × 10⁻⁹ mol / mg or less, more preferably 2.7 × 10⁻⁹ mol / mg or less, further preferably 2.5 × 10⁻⁹ mol / mg or less, further preferably 2.0 × 10⁻⁹ mol / mg or less, and especially preferably 1.0 × 10⁻⁹ mol / mg or less.

[0163] Under these conditions, the mechanical strength of the target material 10 can be further improved.

[0164] Specifically, even without oxidation treatment (where the volume resistivity at 25°C is less than 6.0 × 10¹¹ Ω·cm), the Vickers hardness can be achieved to be 460 or higher, preferably 470 or higher, more preferably 480 or higher, even more preferably 490 or higher, even more preferably 500 or higher, and particularly preferably 510 or higher. Furthermore, the flexural strength can be achieved to be 90 MPa or higher, preferably 100 MPa or higher, even more preferably 110 MPa or higher, even more preferably 120 MPa or higher, and even more preferably 130 MPa or higher.

[0165] Furthermore, when oxidation treatment is performed (with a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C), not only can the Vickers hardness be 210 or higher, but it can also be preferably 250 or higher, more preferably 300 or higher, even more preferably 350 or higher, even more preferably 400 or higher, particularly preferably 450 or higher, and especially more preferably 500 or higher. In addition, not only can the flexural strength be 90 MPa or higher, but it can also be preferably 100 MPa or higher, more preferably 110 MPa or higher, even more preferably 120 MPa or higher, and even more preferably 130 MPa or higher.

[0166] Furthermore, these results indicate that the Vickers hardness or relative density of the target material 10 can be further improved before and after heat treatment.

[0167] Specifically, it can not only make the Vickers hardness after heat treatment at 900°C for 5 hours in the atmosphere more than 50% higher than the Vickers hardness before heat treatment, but also preferably more than 70%, more preferably more than 90%, more preferably more than 95%, and more preferably more than 100%.

[0168] Furthermore, it is possible not only to make the relative density after heat treatment in the atmosphere at 900°C for 5 hours more than 95% of the relative density before heat treatment, but also to make it preferably more than 97%, more preferably more than 99%, and more preferably more than 100%.

[0169] Furthermore, there are no particular restrictions on the lower limit of carbon concentration. However, a carbon concentration of 0.1 ppm or higher, preferably 0.5 ppm or higher, more preferably 1 ppm or higher, even more preferably 3 ppm or higher, and even more preferably 5 ppm or higher can mitigate stress caused by the heat load during sputtering, and in particular, can more effectively suppress cracks and notches in the target material 10 during sputtering. Similarly, there are no particular restrictions on the lower limit of carbon content. However, a carbon content of 0.01 × 10⁻⁹ mol / mg or higher, preferably 0.02 × 10⁻⁹ mol / mg or higher, even more preferably 0.05 × 10⁻⁹ mol / mg or higher, and even more preferably 0.1 × 10⁻⁹ mol / mg or higher can mitigate stress caused by the heat load during sputtering, and in particular, can more effectively suppress cracks and notches in the target material 10 during sputtering.

[0170] (e) By appropriately selecting the manufacturing conditions of the target material 10 within the range of the conditions described above, when an oxidation treatment is performed (the volume resistivity at 25°C is 6.0 × 10¹¹ Ω·cm or higher), it is possible not only to make the porosity 12.0% or less, but also to make the porosity preferably 10.0% or less, more preferably 8.00% or less, even more preferably 6.00% or less, even more preferably 4.00% or less, particularly preferably 2.00% or less, especially more preferably 1.00% or less, and even more preferably 0.75% or less. It is possible not only to make the average diameter of the pores 0.60 μm or less, but also to make the average diameter of the pores preferably 0.50 μm or less, more preferably 0.40 μm or less, even more preferably 0.30 μm or less, and even more preferably 0.25 μm or less.

[0171] Furthermore, by appropriately selecting the manufacturing conditions of the target material 10 within the aforementioned range, when an oxidation treatment is performed (with a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C), it is possible not only to make the maximum diameter of the pores 1.0 μm or less, but also to make the maximum diameter of the pores preferably 0.80 μm or less, more preferably 0.62 μm or less, even more preferably 0.60 μm or less, even more preferably 0.50 μm or less, and especially preferably 0.40 μm or less.

[0172] Under these conditions, the mechanical strength of the target material 10 can be further improved.

[0173] Specifically, when oxidation treatment is performed (with a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C), not only can the Vickers hardness be 210 or higher, but it can also be preferably 250 or higher, more preferably 300 or higher, even more preferably 350 or higher, even more preferably 400 or higher, particularly preferably 450 or higher, and especially more preferably 500 or higher. Furthermore, not only can the flexural strength be 90 MPa or higher, but it can also be preferably 100 MPa or higher, more preferably 110 MPa or higher, even more preferably 120 MPa or higher, and even more preferably 130 MPa or higher.

[0174] Furthermore, these results indicate that the Vickers hardness or relative density of the target material 10 can be further improved before and after heat treatment.

[0175] Specifically, when oxidation treatment is performed, the Vickers hardness after heat treatment at 900°C for 5 hours in the atmosphere can be more than 50% greater than the Vickers hardness before heat treatment, and can be preferably more than 70%, more preferably more than 90%, more preferably more than 95%, and more preferably more than 100%.

[0176] Furthermore, it is possible not only to make the relative density after heat treatment in the atmosphere at 900°C for 5 hours more than 95% of the relative density before heat treatment, but also to make it preferably more than 97%, more preferably more than 99%, and more preferably more than 100%.

[0177] Furthermore, there is no particular limitation on the lower limit of the porosity. In general, when the relative density of the target material 10 exceeds 95%, by making the porosity 0.05% or more, preferably 0.10% or more, more preferably 0.15% or more, even more preferably 0.20% or more, and even more preferably 0.25% or more, the stress generated by the heat load during sputtering can be mitigated, and in particular, cracks and gaps in the target material 10 during sputtering can be more effectively suppressed, which is better.

[0178] Furthermore, there is no particular limitation on the lower limit of the average diameter of the voids. Specifically, when the relative density of the target material 10 exceeds 95%, by making the average diameter of the voids 0.05 μm or more, preferably 0.10 μm or more, more preferably 0.15 μm or more, even more preferably 0.20 μm or more, and even more preferably 0.22 μm or more, the stress generated by the heat load during sputtering can be mitigated, and in particular, cracks and notches in the target material 10 during sputtering can be more effectively suppressed, thus being preferable.

[0179] Furthermore, there is no particular limitation on the lower limit of the maximum diameter of the void. Specifically, when the relative density of the target material 10 exceeds 95%, by making the maximum diameter of the void 0.08 μm or more, preferably 0.12 μm or more, more preferably 0.18 μm or more, even more preferably 0.20 μm or more, even more preferably 0.25 μm or more, particularly preferably 0.30 μm or more, and especially more preferably 0.35 μm or more, the stress generated by the heat load during sputtering can be mitigated, and in particular, cracks and notches in the target material 10 during sputtering can be more effectively suppressed, thus being preferable.

[0180] <Other forms disclosed herein> The various forms disclosed herein have been specifically described above. However, this disclosure is not limited to the described forms and various modifications can be made without departing from its main idea. [Example]

[0181] The present disclosure will now be described in more detail based on the embodiments and comparative examples, but the present disclosure is not limited to the following embodiments. First, the apparatus, conditions, methods, etc. used for measuring the target materials prepared in the embodiments and comparative examples will be described.

[0182] <Crystal grain size of target material> Sample preparation: The process was carried out by abrasion (using water-resistant abrasive paper for abrasion, followed by polishing until any major damage that would hinder the evaluation disappeared). Apparatus: SU-70 ultra-high resolution analytical scanning electron microscope manufactured by Hitachi High-Tech Co., Ltd. TSL Solutions, Inc. manufactures EBSD detectors. Analysis Software: OIM Analysis Ver8, manufactured by TSL Solutions, Inc. Magnification ratio: 3000x Measurement area: 30 μm × 50 μm Step size: 0.06 μm Grain boundary angle: 15° Crystallization information of KNN: The space group and lattice constant were determined by X-ray diffraction, and the information shown in Table 1 below was used. Analysis Method: To remove noise, a clean-up process was performed. A grain boundary map was created with a grain boundary angle of 15° (boundaries with a crystal orientation difference of 15° or more were considered grain boundaries), and grain size was analyzed. For the presence of voids, a threshold value was set for the Image Quality (IQ) value. The area and grain size (circular equivalent diameter) of each particle were calculated using the EBSD number method and area fraction method, and the number-mean grain size, area-mean grain size, and standard deviation were determined. Furthermore, during grain size calculation, to remove poorly crystallized portions or microcrystals that could not be analyzed as noise, particles larger than 0.20 μm were included in the calculation. The number-mean standard deviation Nn (μm) can be calculated based on the distribution of the crystal grain size of each crystal (the diameter when the crystal area is assumed to be a circle). The grain size of each crystal obtained when calculating the number-mean grain size is set as Di, and the following formula is used to calculate it.

[0183] The standard deviation of the quantity mean, Nn(μm), is given by: 〔{Σ(Di - Nd)2} / Σi〕1 / 2

[0184] <Crystal orientation of target material> Sample preparation: The process was carried out by abrasion (using water-resistant abrasive paper for abrasion, followed by polishing until any major damage that would hinder the evaluation disappeared). Apparatus: SU-70 ultra-high resolution analytical scanning electron microscope manufactured by Hitachi High-Tech Co., Ltd. TSL Solutions, Inc. manufactures EBSD detectors. Analysis Software: OIM Analysis Ver8, manufactured by TSL Solutions, Inc. Magnification ratio: 3000x Measurement area: 30 μm × 50 μm Step size: 0.06 μm Grain boundary angle: 15° Azimuth error (allowable angle) during analysis: 0~10° Crystallization information of KNN: The space group and lattice constant were determined by X-ray diffraction, and the information shown in Table 1 below was used. Analytical Method: The evaluation of crystal orientation was performed by preparing an inverse pole diagram of the crystal plane orientation of each sample using the EBSD method (allowable angle 0~10°). Based on the inverse pole diagrams of the crystal plane orientations of the samples from the Examples and Comparative Examples, the area fraction of each crystal orientation was measured. At this time, crystal planes with an inclination of 0~10° from the normal direction of each crystal plane were considered as the same orientation. <103> The area ratio is set as <103> area ratio and <301> The total area ratio, <010> The area ratio is set as <010> area ratio and <002> The total area ratio.

[0185] [Table 1] Crystal system Lattice constant [Å] Angle [°] a b c α, β, γ Tetragonal crystal 7.991 7.991 7.972 90

[0186] <Porosity and pore diameter of target material> Sample preparation: The process was carried out by abrasion (using water-resistant abrasive paper for abrasion, followed by polishing until any major damage that would hinder the evaluation disappeared). Apparatus: SU-8000 ultra-high resolution field emission scanning electron microscope manufactured by Hitachi High-Tech Co., Ltd. Magnification ratio: 5000x Analysis Method: For the SEM images acquired using the aforementioned apparatus and conditions, the image analysis software "Adobe Photoshop" was used to binarize the void regions and the parent image, calculate the area ratio of the void regions relative to the measured area, and calculate the porosity. Additionally, the image processing software "ScnImage" was used to calculate the area of ​​each void, and the diameter of each void (circle equivalent diameter) was also calculated, assuming the shape to be an equivalent circle. The average diameter of the voids was determined by calculating the circle equivalent diameter based on the area that is 50% of the total calculated void areas. The maximum diameter of the voids was extracted from the calculated void diameters.

[0187] Vickers Hardness The Vickers hardness of the target materials in the examples and comparative examples was determined using the following apparatus, conditions, and methods. Equipment: Mitutoyo HM-114 Micro Vickers Hardness Tester (manufactured by Mitutoyo Corporation) Atmosphere: In the atmosphere Temperature: Room temperature (25℃) Test force: 1.0 kgf Load application rate: 10 μm / s Duration: 15 sec Number of measurement points: 5 points Test method: This test is based on JIS R 1610. The Vickers hardness is determined by the test force when a Vickers indenter (a square pyramid indenter with a 136-degree angle between its two opposing faces and a square base) is used to create a depression on the test surface, and by the surface area of ​​the depression calculated from the diagonal length of the depression. The average value is then calculated based on the results of the measurements at 5 points.

[0188] <Flexural Strength> The flexural strength of the target materials in the examples and comparative examples was determined using the following apparatus, conditions, and methods. Apparatus: Instron Model 5582 universal testing machine (500 N load cell) Atmosphere: In the atmosphere Temperature: Room temperature (25℃) Test speed: 0.5 mm / min Distance between fulcrums: L = 30 mm Fixture material: SiC Test method: Evaluation was conducted according to JIS R 1601 using a three-point bending test. The test piece (size: 3 mm × 4 mm × 40 mm) was placed on two supports arranged at a certain distance (30 mm). The bending strength was determined based on the maximum load that caused the piece to break when a load was applied to the central point between the supports.

[0189] Relative density The relative density of the target materials in the embodiments and comparative examples was determined using the following apparatus and method. Device: Alfa Mirage MDS300 electronic hydrometer Test method: For target material cut to specified dimensions, the density was determined using the aforementioned apparatus and the Archimedes method. The relative density (%) was calculated by dividing the calculated density by the theoretical density of KNN (4.52 g / cm³) (= measured density / theoretical density × 100).

[0190] <Carbon Concentration> The carbon concentration (carbon impurity mass) of the target materials in the examples and comparative examples was determined using a combustion-infrared absorption method. Specifically, the cut target material sample was rapidly heated in a high-temperature furnace to separate the CO and CO2 generated from the sample, and the carbon concentration was determined using infrared spectroscopy.

[0191] <Carbon Composition Analysis> The amount of carbon in the target materials of the examples and comparative examples was determined by TDS analysis using the following apparatus, conditions, and methods. Apparatus: TDS1200II manufactured by Electronic Science & Technology Corporation Temperature conditions: Measurement temperature RT-1200℃ (30℃ / min) Thermocouple control T1 Sample stage Quartz stage / SiC disk / sample / quartz dome Quadrupole mass spectrometer (QMS) Free electron method Measurement mode Bar mode (integer mass number measurement mode) Measurement range m / z 1-100 (cumulative time 50 ms / ch) Analytical method: A portion of the target material of the examples and comparative examples before and after oxidation treatment was taken out and pulverized in the atmosphere using a mortar until there was no roughness (particle size less than 50 μm at one time), and about 3 mg of pulverized powder was prepared. The mixture was heated from room temperature to 1200°C, and the ionic strengths of the component with a mass number (m / z) of 28 (carbon monoxide) and the component with a mass number of 44 (carbon dioxide) were determined using a mass analysis device. The amounts of carbon dioxide and carbon monoxide desorbed at 700°C to 1000°C were then calculated. In this embodiment, m / z=28 was considered as carbon monoxide and m / z=44 was considered as carbon dioxide to determine the mole number of each gas desorbed per unit mass of target material (powder).

[0192] <Insulation Evaluation> The insulation properties of the target materials in the embodiments and comparative examples were evaluated by measuring the volume resistivity using the following apparatus, tests, and methods. Equipment: Screen printing press manufactured by Mitani Micronics Co., Ltd., Model MEC=2400E Nishiyama Manufacturing Co., Ltd. manufactures resistivity measuring devices. ADC Corporation manufactures the digital ultra-high resistance / micro current meter, model 5450. Test method: DC three-terminal method Measurement temperature: room temperature (25℃) Measurement atmosphere: Argon atmosphere (99.9999% Ar purity, flow rate 300 cc / min) Measurement method: Using a screen printing machine and platinum paste manufactured by Tanaka Kikinzoku Kogyo K.K., main electrodes and protective electrodes are formed on the upper surface of a target material sample cut to a specified size, and a counter electrode is formed on the lower surface of the target material sample. Each electrode can be formed by drying the platinum paste printed on the sample at 150 °C for 12 hours and then performing a baking treatment (Ar atmosphere, 1000 °C) using an atmospheric tube furnace. After keeping the sample with electrodes in an environment at room temperature (25 °C) for 15 minutes, a DC voltage of 100 V is applied, the current after charging for 1 minute is measured, the volume resistance of the sample is obtained, and the volume resistivity is calculated based on the thickness and electrode area of the sample.

[0193] <BET specific surface area of KNN raw material powder> The BET specific surface area of the KNN raw material powder obtained in the production example is measured by the BET one-point method based on nitrogen adsorption using a specific surface area measuring device (Monosorb, manufactured by Quantachrome Instruments).

[0194] [Manufacture of KNN raw material powder 1] <Production Example 1> K2CO3 powder, Na2CO3 powder, and Nb2O5 powder are prepared as starting raw material powders. By the method described in Japanese Patent Laid-Open No. 2018-197181, the raw material powders are mixed, fired at 650 °C for 7 hours, and pulverized in such a way that in terms of atomic conversion, it becomes 32.5 mol% sodium, 17.5 mol% potassium, 50.0 mol% niobium, the ratio of alkali metals to niobium ((Na + K) / Nb) is 1.00, and the ratio of potassium to sodium and potassium (K / (Na + K)) is 0.35, thereby obtaining KNN raw material powder 1 in which K, Na, and Nb are solid-solved. Regarding the composition of the obtained KNN raw material powder 1, after acid dissolution, it is measured using an inductively coupled plasma optical emission spectrometer, and it is confirmed that it is roughly consistent with the input ratio, and it is confirmed to be a solid solution of K, Na, and Nb by X-ray diffraction analysis. In addition, the BET specific surface area of KNN raw material powder 1 is 6.9 m2 / g.

[0195] [Manufacture of KNN raw material powder 2] <Production Example 2> Using an electric furnace, the KNN raw material powder 1 obtained in Manufacturing Example 1 was calcined at 750°C for 5 hours, followed by calcination at 1000°C for 5 hours. The calcined KNN raw material powder 1 was then pulverized using a jet mill (manufactured by Aishin Nano Technologies Co., Ltd., Nano Jetmizer NJ100 model) at a processing speed of 2 kg / h, an induction pressure of 1.4 MPa, and a pulverization pressure of 1.4 MPa to obtain KNN raw material powder 2. The BET specific surface area of ​​the obtained KNN raw material powder 2 was 4.0 m² / g.

[0196] [Manufacturing of KNN Raw Material Powder 3] <Manufacturing Example 3> Using an electric furnace, the KNN raw material powder 1 obtained in Manufacturing Example 1 was calcined at 750°C for 5 hours, and then calcined at 1000°C for 5 hours to obtain KNN raw material powder 3. The BET specific surface area of ​​the obtained KNN raw material powder 3 is 3.3 m² / g.

[0197] [Manufacturing KNN Raw Material Powder 4] <Manufacturing Example 4> Using an electric furnace, the KNN raw material powder 1 obtained in Manufacturing Example 1 was calcined at 750°C for 5 hours, and then calcined at 900°C for 5 hours to obtain KNN raw material powder 4. The BET specific surface area of ​​the obtained KNN raw material powder 4 is 3.6 m² / g.

[0198] [Manufacturing KNN Raw Material Powder 5] <Manufacturing Example 5> K₂CO₃ powder, Na₂CO₃ powder, and Nb₂O₅ powder were prepared as starting materials and mixed with a [K / (K+Na)] value of 0.35 and a [(Na+K) / Nb] value of 1.00. MnO powder and CuO powder were mixed with a specified concentration of Mn and Cu, and the mixture was calcined at 650°C for 7 hours, followed by pulverization to obtain KNN raw material powder 5, which is a solid solution of K, Na, and Nb. The composition of the obtained KNN raw material powder 5 was determined using a high-frequency inductively coupled plasma optical emission spectrophotometer after acid dissolution, confirming that it was approximately consistent with the input ratio. X-ray diffraction analysis confirmed that it was a solid solution of K, Na, and Nb. Furthermore, the BET specific surface area of ​​KNN raw material powder 5 was 6.9 m² / g.

[0199] [Manufacturing of KNN Raw Material Powder 6] <Manufacturing Example 6> Using an electric furnace, the KNN raw material powder 5 obtained in Manufacturing Example 5 was calcined at 1000°C for 5 hours. The calcined KNN raw material powder 1 was then pulverized using a jet mill (manufactured by Aishin Nano Technologies Co., Ltd., Nano Jetmizer NJ100 model) at a processing speed of 2 kg / h, an induction pressure of 1.4 MPa, and a pulverization pressure of 1.4 MPa to obtain KNN raw material powder 6. The BET specific surface area of ​​the obtained KNN raw material powder 6 was 4.4 m² / g.

[0200] [Manufacturing of KNN Raw Material Powder 7] <Manufacturing Example 7> 150 g of a 10 wt% potassium hydroxide aqueous solution and 100 g of Nb₂O₅ powder were placed in a sealed container made of Teflon (registered trademark), and hydrothermal synthesis was carried out at 210°C for 24 hours. After the reaction, solid-liquid separation was performed to recover the reactants. The recovered reactants were washed with water and dried to obtain KNbO₃ powder. Similarly, 150 g of a 10 wt% sodium hydroxide aqueous solution and 100 g of Nb₂O₅ powder were placed in a sealed container made of Teflon (registered trademark), and hydrothermal synthesis was carried out at 210°C for 24 hours. After the reaction, solid-liquid separation was performed to recover the reactants. The recovered reactants were washed with water and dried to obtain NaNbO₃ powder. KNbO3 powder and NaNbO3 powder, obtained through hydrothermal synthesis, were weighed and mixed according to the following atomic conversion formula: sodium 32.5 mol%, potassium 17.5 mol%, niobium 50.0 mol%, with an alkali metal to niobium ratio ((Na+K) / Nb) of 1.00 and a potassium to sodium and potassium ratio (K / (Na+K)) of 0.35. The mixture was then pulverized using a ball mill (ethanol as solvent) to obtain KNN raw material powder 7. In the obtained KNN raw material powder 7, K, Na, and Nb were not dissolved. The composition of the obtained KNN raw material powder 7 was determined using a high-frequency inductively coupled plasma optical emission spectrophotometer after acid dissolution, confirming that it was approximately consistent with the input ratio. Furthermore, the BET specific surface area of ​​KNN raw material powder 7 was 10.5 m² / g.

[0201] [Example 1] The KNN raw material powder 2 obtained in Manufacturing Example 2 was heated to 200°C and dried. It was then placed in a pulse-driven pressure sintering apparatus SPS9.40MK-VII (manufactured by SPS Syntex Inc.) comprising a graphite mold measuring ϕ170 mm × ϕ101.6 mm × t100 mm and a graphite punch measuring ϕ101.6 mm × t65 mm. Heating was initiated using a discharge plasma under a vacuum atmosphere (atmosphere pressure less than 10 Pa) and a pressure of 10 MPa, increasing the temperature from 25°C to 900°C at a rate of 50°C / min. During this process, desorption of gaseous components was observed, confirming the increase in atmosphere pressure. The pressure was then gradually increased to 35 MPa, followed by a temperature increase to 950°C at a rate of 2.5°C / min, and maintained at 950°C for 30 minutes. Then, the power supply and pressure were stopped and the material was cooled to obtain a disc-shaped target material (KNN sintered body, target material with low insulation) with a diameter of about 101 mm and a thickness of 5 mm.

[0202] In addition, the obtained target material is subjected to oxidation treatment at 900°C for 5 hours under atmospheric conditions, and then the surface is ground for finishing, thereby obtaining a KNN target material (a target material with high insulation) with a diameter of 100 mm and a thickness of 5 mm.

[0203] The composition of the obtained target material was determined using a high-frequency inductively coupled plasma luminescence spectrophotometer after microwave decomposition, confirming that the value of [K / (K+Na)] was 0.35 and the value of [(Na+K) / Nb] was 1.0.

[0204] <Conditions for Low-Pressure SPS> Mechanical pressure: 10 MPa Heating temperature: ~900℃ Atmospheric pressure (pressure within the chamber): less than 10 Pa (30 Pa during rise).

[0205] <Conditions for formally pressurizing the SPS> Mechanical pressure: 35 MPa (pressurization begins at 900℃) Heating temperature: 950℃ Atmospheric pressure (pressure within the chamber): less than 10 Pa

[0206] [Example 2] Using the KNN raw material powder 3 obtained in Manufacturing Example 3, and performing formal pressurized SPS under the conditions shown below, a KNN target material with a diameter of 100 mm and a thickness of 5 mm was obtained by the same method as in Example 1.

[0207] <Conditions for formally pressurizing SPS> Mechanical pressure: 30 MPa (pressurization begins at 900℃) Heating temperature: 1020℃ (increase the temperature by 10℃ / minute from 900℃, and hold at 1020℃ for 75 minutes). Atmospheric pressure (pressure within the chamber): less than 10 Pa

[0208] [Example 3] Using the KNN raw material powder 4 obtained in Manufacturing Example 4, and performing formal pressure SPS under the conditions shown below, a KNN target material with a diameter of 100 mm and a thickness of 5 mm was obtained by the same method as in Example 1.

[0209] <Conditions for formally pressurizing SPS> Mechanical pressure: 40 MPa (pressurization begins at 900℃) Heating temperature: 900℃~1010℃ (increases from 900℃ to 1010℃ at a rate of 2.5℃ / minute, with no holding time) Atmospheric pressure (pressure within the chamber): less than 10 Pa

[0210] [Example 4] Using the KNN raw material powder 6 obtained in Manufacturing Example 6, low-pressure SPS and formal-pressure SPS were performed under the conditions shown below. Otherwise, a KNN target material with a diameter of 100 mm and a thickness of 5 mm was obtained by the same method as in Example 1.

[0211] <Conditions for Low-Pressure SPS> Mechanical pressure: 5 MPa Heating temperature (temperature during degassing): ~800℃ (increases from 25℃ to 800℃ at a rate of 3℃ / minute). Atmospheric pressure (pressure within the chamber): less than 10 Pa (30 Pa during rise).

[0212] <Conditions for formally pressurizing SPS> Mechanical pressure: 40 MPa (pressurization begins at 800℃) Heating temperature: 900℃ (start from 800℃ and increase to 900℃ at a rate of 3℃ / minute, then hold for 3 hours) Atmospheric pressure (pressure within the chamber): less than 10 Pa

[0213] [Example 5] Using the KNN raw material powder 7 obtained in Manufacturing Example 7, a KNN target material with a diameter of 100 mm and a thickness of 5 mm was obtained by the same method as in Example 1.

[0214] [Comparative Example 1] Using the KNN raw material powder 1 obtained in Manufacturing Example 1, low-pressure SPS and formal-pressure SPS were performed under the conditions shown below. Otherwise, a KNN target material with a diameter of 100 mm and a thickness of 5 mm was obtained by the same method as in Example 1.

[0215] <Conditions for Low-Pressure SPS> Mechanical pressure: 10 MPa Heating temperature: 400℃ (start from 25℃, increase the temperature to 400℃ at a rate of 40℃ / minute, and then hold for 50 minutes) Atmospheric pressure (pressure within the chamber): less than 10 Pa (20 Pa during rise).

[0216] <Conditions for formally pressurizing SPS> Mechanical pressure: 40 MPa (pressurization begins at 400℃) Heating temperature: ~915℃ (starting from 400℃, increase the temperature at 10℃ / min to 600℃ and hold for 20 minutes, then increase the temperature at 5℃ / min to 700℃ and hold for 30 minutes, then increase the temperature at 1.3℃ / min to 915℃ and hold for 45 minutes) Atmospheric pressure (pressure within the chamber): less than 10 Pa

[0217] [Comparative Example 2] Using the KNN raw material powder 5 obtained in Manufacturing Example 5, low-pressure SPS and formal-pressure SPS were performed under the conditions shown below. Otherwise, a KNN target material with a diameter of 100 mm and a thickness of 5 mm was obtained by the same method as in Example 1.

[0218] <Conditions for Low-Pressure SPS> Mechanical pressure: 10 MPa Heating temperature: 400℃ (start from 25℃, increase to 400℃ at a rate of 13℃ / minute, and hold for 60 minutes) Atmospheric pressure (pressure within the chamber): less than 10 Pa (20 Pa during rise).

[0219] <Conditions for formally pressurizing SPS> Mechanical pressure: 40 MPa (pressurization begins at 400℃) Heating temperature: ~910℃ (starting from 400℃, increase the temperature at 4℃ / min to 800℃, then increase it at 1.2℃ / min to 910℃ and hold for 10 minutes) Atmospheric pressure (pressure within the chamber): less than 10 Pa

[0220] [Comparative Example 3] Using the KNN raw material powder 1 obtained in Manufacturing Example 1, formal pressure SPS was performed under the conditions shown below without low-pressure SPS. Otherwise, a KNN target material with a diameter of 100 mm and a thickness of 5 mm was obtained by the same method as in Example 1.

[0221] <Conditions for Low-Pressure SPS> Not implemented

[0222] <Conditions for formally pressurizing SPS> Mechanical pressure: 40 MPa (pressurization begins at 25°C) Heating temperature: 800℃ (start from 25℃, increase to 800℃ at a rate of 50℃ / minute, and hold for 160 minutes) Atmospheric pressure (pressure within the chamber): less than 10 Pa (30 Pa during rise).

[0223] <Evaluation of Crystal Grain Size> The sputtered surfaces of the target materials prepared in Examples 1 to 4 and Comparative Example 1 were observed using EBSD, and the number average particle size Nd (μm), area average particle size Nv (μm), number average standard deviation Nn (μm), area average standard deviation Ns (μm), (Nv-Nd) / Nd, and Ns / Nv of the multiple grains observed on the sputtered surface were calculated respectively.

[0224] In addition, the Vickers hardness, relative density, and flexural strength of the target materials of Examples 1 to 4 and Comparative Example 1 were measured respectively.

[0225] Regarding the Vickers hardness and relative density of the target material, measurements were taken at two points: before oxidation treatment (volume resistivity less than 6.0 × 10¹¹ Ω·cm at 25°C) and after oxidation treatment (volume resistivity greater than 6.0 × 10¹¹ Ω·cm at 25°C). Furthermore, the target materials obtained in the examples and comparative examples all had a volume resistivity of less than 6.0 × 10¹¹ Ω·cm at 25°C before oxidation treatment and a volume resistivity of greater than 6.0 × 10¹¹ Ω·cm at 25°C after oxidation treatment. Regarding flexural strength, measurements were taken after oxidation treatment. Furthermore, the flexural strength does not change due to oxidation treatment, or may slightly decrease due to the removal of carbon as an impurity from the sintered body; therefore, the flexural strength before oxidation treatment is greater than or equal to the flexural strength after oxidation treatment.

[0226] The results of these measurements are shown in Table 2.

[0227] [Table 2] Average quantity Particle size Nd [μm] Average quantity Standard deviation Nn [μm] Average area Particle size Nv [μm] Average area Standard deviation Ns [μm] (Nv-Nd) / Nd Ns / Nv Flexural strength [MPa] Vickers hardness relative density [%] Before oxidation treatment After oxidation treatment Before oxidation treatment After oxidation treatment Example 1 0.34 0.14 0.48 0.22 0.41 0.46 199 510 527 98.7 98.5 Example 2 0.60 0.36 1.05 0.50 0.75 0.48 115 470 471 99.6 99.6 Example 3 0.49 0.23 0.71 0.29 0.45 0.41 137 510 508 99.3 99.3 Example 4 0.71 0.38 1.21 0.67 0.70 0.55 166 464 447 98.4 97.3 Comparative Example 1 0.55 0.47 1.74 1.35 2.16 0.78 60 450 210 97.3 88.9

[0228] Regarding the target materials of Examples 1 to 4, it can be confirmed that the area-average particle size Nv (μm) and the area-average standard deviation Ns (μm) are relatively small, (Nv-Nd) / Nd is less than 2.1, and Ns / Nv is less than 0.76.

[0229] Furthermore, in the target materials of Examples 1 to 4, it was confirmed that the Vickers hardness was 460 or higher before oxidation treatment and 250 or higher after oxidation treatment. Additionally, in the target materials of Examples 1 to 4, the flexural strength was confirmed to be 90 MPa or higher after oxidation treatment. Therefore, it can be deduced that the flexural strength of the target materials of Examples 1 to 4 was also 90 MPa or higher before oxidation treatment. Because the target materials of Examples 1 to 4 possess these mechanical strength properties, it was confirmed that no cracks or notches occurred during grinding or subsequent sputtering film formation.

[0230] In addition, regarding the target materials of Examples 1 to 4, the Vickers hardness before and after oxidation treatment was compared. The results confirmed that these values ​​did not change significantly, and the Vickers hardness after heat treatment (oxidation treatment) remained at more than 50% of the Vickers hardness before heat treatment.

[0231] In addition, regarding the target materials of Examples 1 to 4, the relative density before and after oxidation treatment was compared. The results confirmed that these values ​​did not change significantly, and the relative density after heat treatment (oxidation treatment) remained at more than 95% of the relative density before heat treatment.

[0232] In contrast, in the target material of Comparative Example 1, it can be confirmed that the area-average particle size Nv (μm) and the area-average standard deviation Ns (μm) are relatively large, (Nv-Nd) / Nd exceeds 2.1, and Ns / Nv exceeds 0.76.

[0233] Furthermore, in the target material of Comparative Example 1, it was confirmed that the Vickers hardness was less than 460 before oxidation treatment and less than 250 after oxidation treatment. Additionally, in the target material of Comparative Example 1, it was confirmed that the flexural strength was less than 90 MPa after oxidation treatment. Therefore, it can be inferred that the flexural strength in Comparative Example 1 was also less than 90 MPa before oxidation treatment. In the target material of Comparative Example 1, it was confirmed that cracks and notches occurred during grinding and subsequent sputtering film formation. In the sputtering film formation, a sputtering target was used, which was formed by bonding the target material to an oxygen-free copper backplate using In solder.

[0234] In addition, regarding the target material of Comparative Example 1, the Vickers hardness before and after oxidation treatment was compared. The results confirmed that these values ​​changed significantly, and the Vickers hardness after heat treatment (oxidation treatment) was reduced to less than 50% compared to the Vickers hardness before heat treatment.

[0235] In addition, regarding the target material of Comparative Example 1, the relative density before and after the oxidation treatment was compared. The results confirmed that these values ​​also changed significantly. The relative density after heat treatment (oxidation treatment) was reduced to less than 95% of the relative density before heat treatment.

[0236] Furthermore, in Examples 1 to 4, the standard deviation of the quantity mean Nn was less than 0.47 μm, the standard deviation of the area mean Ns was less than 1.35 μm, and thus Nn / Nd was less than 0.85 (0.41 in Example 1, 0.60 in Example 2, 0.47 in Example 3, 0.54 in Example 4, and 0.85 in Comparative Example 1), which was smaller than that in Comparative Example 1, thus confirming that the particle size deviation was small.

[0237] <Evaluation of Crystallization Orientation> The sputtered surfaces of the target materials prepared in Examples 1-4 and Comparative Example 2 were observed using EBSD, and the crystal plane orientations of multiple grains observed within the observation area were measured. The properties of each grain were also measured when the area of ​​the observation area was set to 1. <101> The area ratio A of the crystal planes in the 0-10° orientation <101> ,have <010> The area ratio A of the crystal planes in the 0-10° orientation <010> ,have <111> The area ratio A of the crystal planes in the 0-10° orientation <111> ,have <103> The area ratio A of the crystal planes in the 0-10° orientation <103> ,have <212> The area ratio A of the crystal planes in the 0-10° orientation <212> ,have <121> The area ratio A of the crystal planes in the 0-10° orientation <121> And the total area ratio A of these. Then, based on the measurement results, A is calculated respectively. <103> / A、A <212> + <121> / A、A <101> / A、A.

[0238] In addition, the Vickers hardness, relative density, and flexural strength of the target materials prepared in Examples 1 to 4 and Comparative Example 2 were measured respectively.

[0239] Regarding the Vickers hardness and relative density of the target material, measurements were taken at two points: before oxidation treatment (volume resistivity less than 6.0 × 10¹¹ Ω·cm at 25°C) and after oxidation treatment (volume resistivity greater than 6.0 × 10¹¹ Ω·cm at 25°C). Furthermore, the target materials obtained in the examples and comparative examples all had a volume resistivity of less than 6.0 × 10¹¹ Ω·cm at 25°C before oxidation treatment and a volume resistivity of greater than 6.0 × 10¹¹ Ω·cm at 25°C after oxidation treatment. Regarding flexural strength, measurements were taken after oxidation treatment. Furthermore, flexural strength does not change due to oxidation treatment, or may slightly decrease due to the removal of carbon as an impurity from the sintered body; therefore, the flexural strength before oxidation treatment is greater than or equal to the flexural strength after oxidation treatment.

[0240] The results of these measurements are shown in Table 3. Furthermore, Table 3 shows... <101> , <010> , <111> , <103> , <212> , <121> A represents the area fraction (A) of the sputtered surface per unit area. <101> Area ratio A <010> Area ratio A <111> Area ratio A <103> Area ratio A <212> Area ratio A <121> Therefore, the sum of these values, resulting in a total area ratio A, can be considered equivalent to the total area ratio A per unit area of ​​the sputtered surface.

[0241] [Table 3] Crystallization orientation ratio (0~10°) Flexural strength [MPa] Vickers hardness relative density [%] <101> <010> <111> <103> <212> <121> total Area ratio A <103> / A ( <212> +<121 >) / A <101> / A Before oxidation treatment After oxidation treatment Before oxidation treatment After oxidation treatment Example 1 0.045 0.042 0.060 0.088 0.106 0.128 0.469 0.188 0.500 0.101 199 510 527 98.7 98.5 Example 2 0.065 0.050 0.052 0.124 0.099 0.111 0.501 0.248 0.419 0.130 115 470 471 99.6 99.6 Example 3 0.041 0.042 0.060 0.119 0.096 0.117 0.475 0.251 0.448 0.086 137 510 508 99.3 99.3 Example 4 0.03 0.074 0.055 0.094 0.085 0.147 0.485 0.194 0.478 0.062 166 464 447 98.4 97.3 Comparative example 2 0.012 0.048 0.034 0.060 0.039 0.178 0.371 0.162 0.585 0.032 70 440 190 97.3 90.0

[0242] In Examples 1 through 4, A can be confirmed. <103> A is above 0.061. <103> / A is above 0.165, A <212> + <121> / A is below 0.580, and A is above 0.40. Furthermore, except for Example 2, A can be confirmed to be... <101> / A is less than 0.13.

[0243] Furthermore, in Examples 1 to 4, it was confirmed that the Vickers hardness was 460 or higher before oxidation treatment and 250 or higher after oxidation treatment. Additionally, in Examples 1 to 4, it was confirmed that the flexural strength was 90 MPa or higher after oxidation treatment. Therefore, it can be inferred that the flexural strength was also 90 MPa or higher before oxidation treatment in Examples 1 to 4. Because of these mechanical strength characteristics, it was confirmed that no cracks or gaps occurred during grinding and subsequent sputtering film formation processes in Examples 1 to 4.

[0244] In addition, regarding Examples 1 to 4, the Vickers hardness before and after the oxidation treatment was compared. The results confirmed that these values ​​did not change significantly, and the Vickers hardness after heat treatment (oxidation treatment) remained at more than 50% of the Vickers hardness before heat treatment.

[0245] In addition, regarding Examples 1 to 4, the relative densities before and after the oxidation treatment were compared, and the results confirmed that these values ​​did not change significantly. The relative density after heat treatment (oxidation treatment) remained at more than 95% of the relative density before heat treatment.

[0246] In contrast, in Comparative Example 2, it can be confirmed that A <103> Less than 0.061, A <103> / A is less than 0.165, A <212> + <121> / A > 0.580, A < 0.40.

[0247] Furthermore, in Comparative Example 2, it was confirmed that the Vickers hardness was less than 460 before the oxidation treatment and less than 250 after the oxidation treatment. Additionally, in Comparative Example 2, it was confirmed that the flexural strength was less than 90 MPa after the oxidation treatment. Therefore, it can be inferred that the flexural strength in Comparative Example 2 was also less than 90 MPa before the oxidation treatment. In Comparative Example 2, it was confirmed that cracks and notches occurred during grinding and subsequent sputtering film formation.

[0248] In addition, regarding Comparative Example 2, the Vickers hardness before and after the oxidation treatment was compared. The results confirmed that these values ​​changed significantly, with the Vickers hardness after heat treatment (oxidation treatment) decreasing to less than 50% compared to the Vickers hardness before heat treatment.

[0249] In addition, regarding Comparative Example 2, the relative densities before and after the oxidation treatment were compared, and the results confirmed that these values ​​also changed significantly. The relative density after heat treatment (oxidation treatment) was reduced to less than 95% of the relative density before heat treatment.

[0250] <Evaluation of carbon concentration> The carbon concentration of the target materials prepared in Examples 1, 3-5 and Comparative Example 1 was measured by combustion-infrared absorption method (instrumental gas analysis) at two times: before oxidation treatment (volume resistivity less than 6.0 × 10 11 Ω·cm at 25°C) and after oxidation treatment (volume resistivity greater than 6.0 × 10 11 Ω·cm at 25°C).

[0251] In addition, the Vickers hardness, relative density, and flexural strength of the target materials prepared in Examples 1, 3 to 5, and Comparative Example 1 were measured respectively.

[0252] Regarding the Vickers hardness and relative density of the target material, measurements were taken at two points: before oxidation treatment (volume resistivity less than 6.0 × 10¹¹ Ω·cm at 25°C) and after oxidation treatment (volume resistivity greater than 6.0 × 10¹¹ Ω·cm at 25°C). Furthermore, the target materials obtained in the examples and comparative examples all had a volume resistivity of less than 6.0 × 10¹¹ Ω·cm at 25°C before oxidation treatment and a volume resistivity of greater than 6.0 × 10¹¹ Ω·cm at 25°C after oxidation treatment. Regarding flexural strength, measurements were taken after oxidation treatment. Furthermore, flexural strength does not change due to oxidation treatment, or may slightly decrease due to the removal of carbon as an impurity from the sintered body; therefore, the flexural strength before oxidation treatment is greater than or equal to the flexural strength after oxidation treatment.

[0253] The results of these measurements are shown in Table 4.

[0254] [Table 4] carbon concentration [wt ppm] Flexural strength [MPa] Vickers hardness relative density [%] Before oxidation treatment After oxidation treatment Before oxidation treatment After oxidation treatment Before oxidation treatment After oxidation treatment Example 1 50 <10 199 510 527 98.7 98.5 Example 3 63 13 137 510 508 99.3 99.3 Example 4 120 12 166 464 447 98.4 97.3 Example 5 20 <5 205 540 543 99.5 99.5 Comparative Example 1 260 95 60 450 210 97.3 88.9

[0255] Regarding the target materials of Examples 1 and 3 to 5, it can be confirmed that the carbon concentration is relatively low, below 200 ppm before oxidation treatment and below 90 ppm after oxidation treatment.

[0256] Furthermore, in the target materials of Examples 1 and 3-5, it was confirmed that the Vickers hardness was 460 or higher before oxidation treatment and 250 or higher after oxidation treatment. Additionally, in the target materials of Examples 1 and 4, it was confirmed that the flexural strength was 90 MPa or higher after oxidation treatment. Therefore, it can be deduced that the flexural strength of the target materials of Examples 1 and 3-5 was also 90 MPa or higher before oxidation treatment. Because the target materials of Examples 1 and 3-5 possess these mechanical strength characteristics, it was confirmed that no cracks or gaps occurred during grinding and subsequent sputtering film formation processes.

[0257] In addition, regarding the target materials of Examples 1 and 3 to 5, the Vickers hardness before and after oxidation treatment was compared. The results confirmed that these values ​​did not change significantly, and the Vickers hardness after heat treatment (oxidation treatment) remained at more than 50% of the Vickers hardness before heat treatment.

[0258] In addition, regarding the target materials of Examples 1 and 3 to 5, the relative densities before and after oxidation treatment were compared. The results confirmed that these values ​​did not change significantly, and the relative density after heat treatment (oxidation treatment) remained at more than 95% of the relative density before heat treatment.

[0259] Furthermore, it was confirmed that the amount of carbon in the target material before oxidation treatment in Example 1 was 0.5 × 10⁻⁹ mol / mg converted to carbon dioxide and 1.4 × 10⁻⁹ mol / mg converted to carbon monoxide, with a total amount of 1.9 × 10⁻⁹ mol / mg. The amount of carbon in the target material before oxidation treatment in Example 4 was 1.6 × 10⁻⁹ mol / mg converted to carbon dioxide and 2.3 × 10⁻⁹ mol / mg converted to carbon monoxide, with a total amount of 3.9 × 10⁻⁹ mol / mg. The total amount of carbon dioxide and carbon monoxide converted was less than 5.0 × 10⁻⁹ mol / mg.

[0260] Furthermore, it can be confirmed that the amount of carbon in the target material after oxidation treatment in Example 4 is 1.2 × 10⁻⁹ mol / mg when converted to carbon dioxide, 1.8 × 10⁻⁹ mol / mg when converted to carbon monoxide, and a total of 3.0 × 10⁻⁹ mol / mg. The total amount of carbon dioxide and carbon monoxide converted is less than 4.0 × 10⁻⁹ mol / mg.

[0261] In contrast, the target material of Comparative Example 1 showed a high carbon concentration, exceeding 200 ppm before oxidation and exceeding 90 ppm after oxidation.

[0262] Furthermore, in the target material of Comparative Example 1, it was confirmed that the Vickers hardness was less than 460 before oxidation treatment and less than 250 after oxidation treatment. Additionally, in the target material of Comparative Example 1, it was confirmed that the flexural strength was less than 90 MPa after oxidation treatment. Therefore, it can be inferred that the flexural strength in Comparative Example 1 was also less than 90 MPa before oxidation treatment. In the target material of Comparative Example 1, it was confirmed that cracks and notches occurred during grinding and subsequent sputtering film formation.

[0263] In addition, regarding the target material of Comparative Example 1, the Vickers hardness before and after oxidation treatment was compared. The results confirmed that these values ​​changed significantly, and the Vickers hardness after heat treatment (oxidation treatment) was reduced to less than 50% compared to the Vickers hardness before heat treatment.

[0264] In addition, regarding the target material of Comparative Example 1, the relative density before and after the oxidation treatment was compared. The results confirmed that these values ​​also changed significantly. The relative density after heat treatment (oxidation treatment) was reduced to less than 95% of the relative density before heat treatment.

[0265] <Evaluation of the gaps> The sputtered surfaces of the target materials prepared in Examples 2, 3, and Comparative Examples 2 and 3 were observed using a scanning electron microscope (SEM), and the ratio of the total area of ​​voids in the sputtered surface, i.e., the porosity (%), the average diameter (μm) of the voids in the sputtered surface, and the maximum diameter (μm) of the voids in the sputtered surface were measured respectively.

[0266] In addition, the Vickers hardness, relative density, and flexural strength of Examples 2 and 3, and Comparative Examples 2 and 3 were measured respectively.

[0267] Regarding Vickers hardness and relative density, measurements were performed at two points: before oxidation treatment (volume resistivity less than 6.0 × 10¹¹ Ω·cm at 25°C) and after oxidation treatment (volume resistivity greater than 6.0 × 10¹¹ Ω·cm at 25°C). Furthermore, the target materials obtained in the examples and comparative examples all had a volume resistivity of less than 6.0 × 10¹¹ Ω·cm at 25°C before oxidation treatment and a volume resistivity of greater than 6.0 × 10¹¹ Ω·cm at 25°C after oxidation treatment. Regarding flexural strength, measurements were performed after oxidation treatment. Furthermore, flexural strength does not change due to oxidation treatment, or may slightly decrease due to the removal of carbon as an impurity from the sintered body; therefore, the flexural strength before oxidation treatment is greater than or equal to the flexural strength after oxidation treatment.

[0268] The results of these measurements are shown in Table 5.

[0269] [Table 5] gaps average diameter [μm] gaps Maximum diameter [μm] porosity [%] Flexural strength [MPa] Vickers hardness relative density [%] Before oxidation treatment After oxidation treatment Before oxidation treatment After oxidation treatment Example 2 0.21 0.29 0.24 115 470 471 99.6 99.6 Example 3 0.25 0.54 0.58 137 510 508 99.3 99.3 Comparative Example 2 0.61 1.11 11.19 70 440 190 97.3 90.0 Comparative Example 3 0.26 0.64 13.25 84 450 220 98.2 93.0

[0270] In both Examples 2 and 3, it was confirmed that the porosity was less than 12.0%, the average diameter of the pores was less than 0.60 μm, and the maximum diameter of the pores was less than 1.0 μm.

[0271] Furthermore, in Examples 2 and 3, it was confirmed that the Vickers hardness was 460 or higher before oxidation treatment and 250 or higher after oxidation treatment. Additionally, in Examples 2 and 3, it was confirmed that the flexural strength was 90 MPa or higher after oxidation treatment. Therefore, it can be inferred that the flexural strength was also 90 MPa or higher before oxidation treatment in Examples 2 and 3. Because of these mechanical strength characteristics, it was confirmed that no cracks or gaps occurred during grinding and subsequent sputtering film formation processes in Examples 2 and 3.

[0272] In addition, regarding Examples 2 and 3, the Vickers hardness before and after the oxidation treatment was compared. The results confirmed that these values ​​did not change significantly, and the Vickers hardness after heat treatment (oxidation treatment) remained at more than 50% of the Vickers hardness before heat treatment.

[0273] In addition, regarding Examples 2 and 3, the relative densities before and after the oxidation treatment were compared, and the results confirmed that these values ​​did not change significantly. The relative density after heat treatment (oxidation treatment) remained at more than 95% of the relative density before heat treatment.

[0274] In contrast, in Comparative Examples 2 and 3, it was confirmed that the porosity exceeded 12.0%, or the average diameter of the pores exceeded 0.6 μm. Furthermore, the maximum diameter of the pores was also greater than the maximum diameter of Examples 2 and 3.

[0275] Furthermore, in Comparative Examples 2 and 3, it was confirmed that the Vickers hardness was less than 460 before the oxidation treatment and less than 250 after the oxidation treatment. Additionally, in Comparative Examples 2 and 3, it was confirmed that the flexural strength was less than 90 MPa after the oxidation treatment. Therefore, it can be inferred that the flexural strength in Comparative Examples 2 and 3 was also less than 90 MPa before the oxidation treatment. In Comparative Examples 2 and 3, it was confirmed that cracks and notches occurred during grinding and subsequent sputtering film formation.

[0276] In addition, regarding Comparative Examples 2 and 3, the Vickers hardness before and after the oxidation treatment was compared. The results confirmed that these values ​​changed significantly, and the Vickers hardness after heat treatment (oxidation treatment) was reduced to less than 50% compared to the Vickers hardness before heat treatment.

[0277] In addition, regarding Comparative Examples 2 and 3, the relative densities before and after the oxidation treatment were compared, and the results confirmed that these values ​​also changed significantly. The relative density after heat treatment (oxidation treatment) was reduced to less than 95% of the relative density before heat treatment.

[0278] <The preferred state disclosed herein> The following is a preferred embodiment disclosed in the appendix.

[0279] (Postscript 1) According to the present invention, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. When the volume resistivity at 25℃ is less than 6.0×10 11Ω·cm, the Vickers hardness is above 460 and the flexural strength is above 90 MPa.

[0280] (Postscript 2) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. When the volume resistivity at 25℃ is above 6.0×10 11Ω·cm, the Vickers hardness is above 250, and the flexural strength is above 90 MPa.

[0281] (Note 3) The preferred option is: The Vickers hardness after heat treatment at 900°C for 5 hours in the atmosphere remains more than 50% of the Vickers hardness before the heat treatment.

[0282] (Note 4) The preferred option is: The relative density after heat treatment at 900°C for 5 hours in the atmosphere remains more than 95% of the relative density before the heat treatment.

[0283] (Note 5) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. Among the multiple grains observed on the sputtered surface, the number-average grain size Nd and the area-average grain size Nv satisfy the relationship (Nv-Nd) / Nd≦2.1.

[0284] (Note 6) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. Among the multiple grains observed on the sputtered surface, the area-average grain size Nv and the area-average standard deviation Ns satisfy the relationship Ns / Nv≦0.76.

[0285] (Note 7) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. The sputtered surface was observed using the EBSD method, and the surface with... <103> Let A be the area ratio of grains in the 0-10° orientation. <103> hour, The area ratio A in each unit area of ​​the sputtered surface <103> It is above 0.061.

[0286] (Postscript 8) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. The sputtered surface was observed using the EBSD method. and will have <101> Crystal planes with orientations of 0-10°, possessing <010> Crystal planes with orientations of 0-10°, possessing <111> Crystal planes with orientations of 0-10°, possessing <103> Crystal planes with orientations of 0-10°, possessing <212> Crystal planes with orientations of 0-10°, and having <121> Let A be the total area ratio of the crystal planes in the 0-10° orientation. Will have <103> Let A be the area ratio of the crystal planes in the 0-10° orientation. <103> hour, The A <103> The ratio relative to A is 0.165 or higher.

[0287] (Note 9) The preferred option is: The sputtered surface was observed using the EBSD method. and will have <212> Crystal planes with orientations of 0-10°, and having <121> Let A be the total area ratio of the crystal planes in the 0-10° orientation. <212> + <121> hour, The A <212> + <121> The ratio relative to A is less than 0.580.

[0288] (Postscript 10) The preferred option is: The sputtered surface was observed using the EBSD method. and will have <101> Let A be the area ratio of the crystal planes in the 0-10° orientation. <101> hour, The A <101> The ratio relative to A is less than 0.130.

[0289] (Postscript 11) The preferred option is: The total area ratio A per unit area of ​​the sputtered surface, as observed by the EBSD method, is 0.40 or higher.

[0290] (Postscript 12) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. The carbon concentration is below 200 ppm when the volume resistivity at 25℃ is less than 6.0×10 11Ω·cm.

[0291] (Postscript 13) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. The carbon concentration is below 90 ppm when the volume resistivity at 25℃ is above 6.0×10 11Ω·cm.

[0292] (Postscript 14) According to another aspect of this disclosure, a sputtering target material is provided, comprising a sintered body containing oxides of potassium, sodium, niobium, and oxygen. In the sputtering target material, the carbon content, when the volume resistivity at 25°C is less than 6.0 × 10¹¹ Ω·cm relative to the mass of the target material 10 (1 mg), is converted to a total of 5.0 × 10⁻⁹ mol of carbon dioxide and carbon monoxide (i.e., 5.0 × 10⁻⁹ mol / mg or less).

[0293] (Postscript 15) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. Relative to the mass of the target material 10 (1 mg), the carbon content when the volume resistivity at 25°C is above 6.0 × 10¹¹ Ω·cm, converted to a total of carbon dioxide and carbon monoxide, is below 4.0 × 10⁻⁹ mol (i.e., below 4.0 × 10⁻⁹ mol / mg).

[0294] (Postscript 16) According to another aspect of this disclosure, a sputtering target material is provided. The sputtering target material comprises a sintered body containing oxides of potassium, sodium, niobium, and oxygen. The ratio of the total area of ​​voids to the total area of ​​the sputtered surface is less than 12.0%. The average diameter of the voids present on the sputtered surface is less than 0.60 μm.

[0295] (Postscript 17) The preferred option is: The maximum diameter of the voids existing on the sputtered surface is less than 1.0 μm.

[0296] (Postscript 18) The preferred option is: The dopant contains at least one element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga.

[0297] (Postscript 19) The preferred option is: The main surface has an area of ​​over 4500 mm².

[0298] (Postscript 20) According to another aspect of this disclosure, a sputtering target is provided, comprising: sputtering target materials as described in any one of Appendix 1 to Appendix 19; and Backplate, bonded to the sputtering target material.

[0299] 10: Target Material 10s: Sputtered surface 100: Sintering apparatus 101: Chamber 102: Mold (for sintering) 103, 104: Punch 105, 106: Pressurization device 110: Vacuum pump 111: Pressure gauge 120: Pulse power supply device

Claims

1. A sputtering target material comprising a sintered body containing oxides of potassium, sodium, niobium, and oxygen, wherein the sintered body is represented by the formula (K1-xNax)NbO3 (0 < x < 1), wherein the sputtering target material has a volume resistivity of less than 6.0 × 10¹¹ Ω·cm at 25°C, a Vickers hardness of 460 or higher, and a flexural strength of 90 MPa or higher.

2. A sputtering target material comprising a sintered body containing oxides of potassium, sodium, niobium, and oxygen, wherein the sintered body is represented by the formula (K1-xNax)NbO3 (0 < x < 1), wherein the sputtering target material has a volume resistivity of 6.0 × 10¹¹ Ω·cm or higher at 25°C, a Vickers hardness of 250 or higher, and a flexural strength of 90 MPa or higher.

3. The sputtering target material as described in claim 1 or claim 2, wherein, The Vickers hardness after heat treatment at 900°C for 5 hours in the atmosphere remains more than 50% of the Vickers hardness before the heat treatment.

4. The sputtering target material as described in claim 1 or claim 2, wherein, The relative density after heat treatment at 900°C for 5 hours in the atmosphere remains more than 95% of the relative density before the heat treatment.

5. The sputtering target material as described in claim 1 or claim 2, comprising at least one element selected from the group consisting of Li, Mg, Ca, Sr, Ba, Bi, Sb, V, In, Ta, Mo, W, Cr, Ti, Zr, Hf, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Zn, Ag, Mn, Fe, Co, Ni, Al, Si, Ge, Sn, and Ga as a dopant.

6. The sputtering target material as described in claim 1 or claim 2, wherein, The main surface has an area of ​​over 4500 mm2.

7. A sputtering target, comprising: sputtering target material as described in claim 1 or claim 2; And a backplate, which is bonded to the sputtering target material.

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