Dielectric ceramic and ceramic capacitor using same

Abstract

Provided is a dielectric ceramic that can achieve both a low dielectric loss tangent and a high dielectric constant. The dielectric ceramic has a composition comprising, as a main component, a rutile-type compound represented by (TixSn1-x)O2 (0.40 ≤ x ≤ 0.60) and further comprising Nb. In a cross-sectional view, the dielectric ceramic includes regions comprising a Ti-rich phase in which A, defined by equation (1), is 0.55 or greater, and regions comprising a Sn-rich phase in which B, defined by equation (2), is 0.55 or greater, and the dielectric ceramic satisfies equations (3) to (5).　(1): A = (Ti content (atom%)) / (total content (atom%) of Ti and Sn); (2): B = (Sn content (atom%)) / (total content (atom%) of Ti and Sn); (3): 0.005 mol% ≤ y ≤ 0.020 mol%; (4): 16 nm ≤ DTi ≤ 20 nm; (5): 15 nm ≤ DSn ≤ 19 nm, wherein y (mol%) is the content of Nb based on 100 mol% of the content of the rutile-type compound, DTi (nm) is the average dimension of the Ti-rich phase regions, and DSn (nm) is the average dimension of the Sn-rich phase regions.

Description

Dielectric ceramics and ceramic capacitors using the same

[0001] The present invention relates to a dielectric ceramic and a ceramic capacitor using the same.

[0002] Metastable phase Ti 0.5 Sn 0.5 When O2 ceramics is heat-treated and then rapidly cooled, spinodal decomposition occurs, causing phase separation into a phase with a high Ti content (Ti-rich phase) and a phase with a high Sn content (Sn-rich phase), forming a striped structure with a width of 10 to 100 nm.

[0003] Ti 0.5 Sn 0.5 When Nb is added to O ceramics as a donor, electrons are generated as carriers. When the Nb-added ceramics are heat-treated to cause spinodal decomposition, the electrons are blocked by the barrier between the Ti-rich phase and the Sn-rich phase, resulting in a high dielectric constant of the ceramics (see, for example, Non-Patent Document 1).

[0004] W. Chaisan et al., “The effects of the spinodal microstructure on the electrical properties of TiO2-SnO2 ceramics”, Journal of Solid State Chemistry 178 (2005) 613-620

[0005] Ceramic materials used in electronic components, particularly ceramic capacitors, are desired to have both a high dielectric constant and a low dielectric loss tangent. For example, ceramic materials with a dielectric loss tangent of 0.035 or less at 10 kHz and a dielectric constant of 2400 or more are required. However, the ceramic material disclosed in Non-Patent Document 1 fails to achieve both a low dielectric loss tangent and a high dielectric constant.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a dielectric ceramic that can achieve both a low dielectric loss tangent and a high relative dielectric constant, and to provide a ceramic capacitor using the same.

[0007] According to one aspect of the present invention, the main component is (Ti x Sn 1-x )O2 (0.40≦x≦0.60), and further containing Nb, and in cross section, comprises: a region consisting of a Ti-rich phase in which A defined by the following formula (1) is 0.55 or more; and a region consisting of a Sn-rich phase in which B defined by the following formula (2) is 0.55 or more, and satisfies the following formulas (3) to (5): A=(Ti content (atom %)) / (total content of Ti and Sn (atom %)) (1) B=(Sn content (atom %)) / (total content of Ti and Sn (atom %)) (2) 0.005 mol%≦y≦0.020 mol% (3) 16 nm≦D Ti ≦20 nm (4) 15 nm≦D Sn ≦19 nm (5) where y (mol %) is the content of Nb when the content of the rutile compound is 100 mol %, and D Ti (nm) is the average size of the Ti-rich phase domain, and D Sn (nm) is the average size of the Sn-rich phase domains.

[0008] According to another aspect of the present invention, there is provided a ceramic capacitor comprising a ceramic body containing the dielectric ceramic of the present invention.

[0009] According to a further aspect of the present invention, there is provided a multilayer ceramic capacitor comprising a ceramic body containing the dielectric ceramic of the present invention.

[0010] According to the present invention, it is possible to provide a dielectric ceramic that can achieve both a low dielectric loss tangent and a high relative dielectric constant, and a ceramic capacitor using the same.

[0011] 1 is a schematic diagram for explaining the internal structure in a cross-sectional view of a dielectric ceramic according to embodiment 1 of the present invention. It shows an STEM image of a cross-section of a sample prepared in example 1 of the present invention, and the results of examining the distributions of Ti, Nb, and Sn from the TEM image by EDX analysis. It also shows the results of determining the distributions of Ti-rich phases and Sn-rich phases using the distribution results of Ti and Sn examined by EDX analysis of the TEM image of the cross-section of the sample prepared in example 1 of the present invention. It is a schematic cross-sectional view of a multilayer ceramic capacitor according to embodiment 2.

[0012] Ti disclosed in Non-Patent Document 1 0.5 Sn 0.5 It is difficult to achieve a low dielectric loss tangent in O2 ceramics. The reason for this is unclear, but is presumed to be as follows.

[0013] Ti 0.5 Sn 0.5 O2 ceramics form a striped structure of Ti-rich and Sn-rich phases through spinodal decomposition. The striped structure extends in one direction within one crystal grain. It also extends in one direction within another crystal grain, but the extension direction does not necessarily match the extension direction within adjacent crystal grains. Note that, because it is difficult to control the direction of phase separation that occurs within a crystal grain, it is difficult to intentionally align or intentionally make the extension directions of the striped structure between adjacent crystal grains different.

[0014] The crystal grains that make up ceramics have grain boundaries between adjacent crystal grains. Each of the Ti-rich and Sn-rich phases that make up the banded structure within a crystal grain extends in the form of a thin band and terminates at the grain boundary between adjacent crystal grains. When the end of each rich phase located at the grain boundary comes into contact with the end of the same type of rich phase in the adjacent crystal grain, a current path can be formed between the adjacent crystal grains.

[0015] For example, if an end of a Ti-rich phase in one crystal grain and an end of a Ti-rich phase in an adjacent crystal grain are in contact at the grain boundary, electrons can flow from the Ti-rich phase in one crystal grain through the grain boundary to the Ti-rich phase in the other crystal grain when a voltage is applied to the ceramic. Similarly, if an end of a Sn-rich phase in one crystal grain and an end of a Sn-rich phase in an adjacent crystal grain are in contact at the grain boundary, electrons can flow from the Sn-rich phase in one crystal grain through the grain boundary to the Sn-rich phase in the other crystal grain when a voltage is applied to the ceramic.

[0016] Thus, ceramics in which electrons can move between adjacent crystal grains have the problem of increasing the dielectric loss tangent.

[0017] As a result of extensive research, the inventors have discovered that by controlling the heating conditions during ceramic firing, it is possible to control the Ti-rich and Sn-rich phases produced by spinodal decomposition into island-like structures. In dielectric ceramics with island-like structures, current paths are less likely to form between adjacent crystal grains, making it possible to achieve both a low dielectric loss tangent and a high dielectric constant.

[0018] Hereinafter, a dielectric ceramic according to an embodiment of the present invention and a ceramic capacitor using the same will be described in detail.

[0019] [Embodiment 1] Fig. 1 is a schematic diagram for explaining the internal structure in a cross-sectional view of a dielectric ceramic according to embodiment 1. The dielectric ceramic 10 contains, as a main component, (Ti x Sn 1-x )O2 (0.40≦x≦0.60), and further containing Nb. The dielectric ceramic 10 includes a large number of crystal grains 12 therein and grain boundaries 14 present between the crystal grains 12.

[0020] In a cross-sectional view, the dielectric ceramic 10 includes, within each crystal grain 12, a region (Ti-rich phase region 20) consisting of a Ti-rich phase in which A defined by formula (1) is 0.55 or more, and a region (Sn-rich phase region 30) consisting of a Sn-rich phase in which B defined by formula (2) is 0.55 or more. Within the crystal grain 12, a region that is neither the Ti-rich phase region 20 nor the Sn-rich phase region 30 is a ceramic phase in which A is less than 0.55 and B is less than 0.55 (i.e., the Ti content and Sn content are approximately the same). A = (Ti content (atom %)) / (total content of Ti and Sn (atom %)) (1) B = (Sn content (atom %)) / (total content of Ti and Sn (atom %)) (2)

[0021] The Ti content (atom %) and Sn content (atom %) at each measurement position can be measured by STEM-EDX (acceleration voltage: 200 kV, magnification: 60,000 times).

[0022] The dielectric ceramic 10 further satisfies the following formulas (3) to (5): 0.005 mol %≦y≦0.020 mol % (3) 16 nm≦D Ti ≦20 nm (4) 15 nm≦D Sn ≦19 nm (5) where y (mol %) is the content of Nb when the content of the rutile compound is 100 mol %, and D Ti (nm) is the average size of the Ti-rich phase domain, and D Sn (nm) is the average size of the Sn-rich phase domains.

[0023] Formula (3) defines the content of Nb (donor) contained in the dielectric ceramic 10. By appropriately controlling the Nb content, it is possible to achieve both a low dielectric tangent and a high relative dielectric constant. The Nb content (mol %) can be measured by composition analysis using inductively coupled plasma atomic emission spectroscopy.

[0024] Equation (4) defines the average dimension of the Ti-rich phase region 20, and equation (5) defines the average dimension of the Sn-rich phase region 30. The average dimension is determined by the following procedure. The dielectric ceramic is observed by STEM-EDX (acceleration voltage: 200 kV, magnification: 60,000 times), and the Ti-rich phase region 20 and the Sn-rich phase region 30 are identified from the obtained content data of each element. Using image analysis software (for example, image analysis software winROOF (Mitani Corporation)), 300 Ti-rich phase regions within the observation region are arbitrarily selected, and the maximum dimension of each is measured (Ferret II diameter (horizontal)). The average value of the obtained maximum dimension measurement data (300 data for each Ti-rich phase region) is calculated to obtain the "average dimension D of the Ti-rich phase region 20." Ti (nm)" and "the average dimension D Sn When the number of rich phase regions included in one visual field observation is less than 300, the visual field observation is performed multiple times to select 300 rich phase regions, and the dimensions are measured.

[0025] In the dielectric ceramic 10 according to the first embodiment, the average dimension D of the Ti-rich phase region 20 Ti (nm) to 16 nm≦D Ti ≦20 nm, and the average dimension D of the Sn-rich phase region 30 Sn (nm) is 15 nm≦D Sn The Ti-rich phase regions 20, 30, the dimensions of which are controlled in this manner, have an island-like structure having a certain size, and as a result, the dielectric ceramic 10 can achieve both a low dielectric loss tangent and a high relative dielectric constant. When the dielectric ceramic 10 includes a Ti-rich phase with a striped structure, the maximum dimension of the striped Ti-rich phase is much larger than the maximum dimension of the Ti-rich phase with an island structure, so that the average dimension D Ti Similarly, when the dielectric ceramic 10 includes a striped Sn-rich phase, the maximum dimension of the striped Sn-rich phase is much larger than the maximum dimension of the island-like Sn-rich phase, so the average dimension D Sn (nm) is estimated to be greater than 19 nm.

[0026] Preferably, the average dimension D of the Ti-rich phase region Ti More preferably, the average dimension D of the Ti-rich phase region is 16 nm or more and 18 nm or less. Ti is 16 nm or more and 17 nm or less. A dielectric ceramic 10 that can achieve both a lower dielectric tangent and a higher relative dielectric constant can be obtained.

[0027] In a cross-sectional view, when the area ratio of the dielectric ceramic excluding pores is taken as 100%, the area ratio α (%) of the Ti-rich phase region is preferably 5.50% or more and 7.10% or less. A dielectric ceramic 10 that can achieve both a lower dielectric dissipation factor and a higher relative dielectric constant can be obtained. More preferably, the area ratio α (%) is 5.50% or more and 6.80% or less. A dielectric ceramic 10 that can achieve both an even lower dielectric dissipation factor and an even higher relative dielectric constant can be obtained.

[0028] The phrase "the area ratio of the dielectric ceramic excluding pores is 100%" means that the content data of each element obtained by the above-mentioned STEM-EDX measurement is subjected to image analysis, and the area obtained by subtracting the area of ​​pores from the area of ​​the observation field is taken as 100%. "Pores" refer to hollow portions present in the dielectric ceramic.

[0029] The method for identifying pores using image analysis is as follows. Ti distribution images and Sn distribution images acquired from the same observation site are prepared. The Ti distribution image is analyzed to identify the highest Ti detection intensity within the field of view, and all regions (low Ti concentration regions) with Ti detection intensity less than 1 / 100 of that maximum detection intensity are identified. Similarly, the Sn distribution image is analyzed to identify the highest Sn detection intensity within the field of view, and all regions (low Sn concentration regions) with Sn detection intensity less than 1 / 100 of that maximum detection intensity are identified. Regions that are low Ti concentration regions and low Sn concentration regions are then defined as "pores." Note that in this specification, the "area ratio α (%) of Ti-rich phase regions" is defined as the area ratio calculated from the total area of ​​Ti-rich phase regions within the observation field where the dimension of the continuous Ti-rich phase (i.e., the maximum dimension of the Ti-rich phase region) is 14 nm or more.

[0030] The above various measurements are taken at the center of the dielectric ceramic.

[0031] [Method for manufacturing dielectric ceramics] The dielectric ceramics according to the first embodiment include the following steps 1) to 5): 1) mixing raw materials containing Ti, Sn, and Nb in a predetermined ratio; 2) calcining the mixed raw materials; 3) pressure-molding the calcined powder; 4) firing the molded body at a firing temperature of more than 1505°C and less than 1520°C for a predetermined firing time; and 5) rapid cooling after firing.

[0032] The present invention differs from Non-Patent Document 1 in the following points: In the first embodiment, the firing temperature in step 4) is high (in Non-Patent Document 1, the firing temperature is 1450°C); in the first embodiment, annealing is not performed after step 5) (in Non-Patent Document 1, annealing is performed at 1000°C for 1 to 48 hours after step 5).

[0033] The method for producing the dielectric ceramic according to the first embodiment will be described in detail below.

[0034] 1) Mixing raw materials containing Ti, Sn, and Nb in a predetermined ratio. Raw materials that serve as a Ti source, Sn source, and Nb source are blended so that the contents of Ti, Sn, and Nb are in the desired ratio. Oxides of Ti, Sn, and Nb can be used as raw materials. The raw materials blended in the predetermined ratio are mixed using a device such as a ball mill, high-pressure dispersion, or jet mill. Either dry mixing or wet mixing can be used. In wet mixing, it is preferable to use an organic solvent such as ethanol or an inorganic solvent such as water as the solvent.

[0035] 2) Calcining the mixed raw materials The mixed raw materials are dried and granulated to produce raw material powder. The raw material powder is calcined at 900°C to 1400°C for 1 hour to 24 hours to obtain a solid solution. The calcination is carried out in air, an oxygen atmosphere, or the like. An electric furnace or the like can be used for calcination.

[0036] 3) Pressurizing the calcined powder The calcined powder is granulated and molded into a desired shape. The molding is performed by uniaxial pressing, CIP, WIP, or the like. Alternatively, multiple molding methods may be applied sequentially. For example, CIP may be applied after molding by uniaxial pressing.

[0037] 4) Sintering the compact at a firing temperature of greater than 1505°C and less than 1520°C for a predetermined firing time. The compact is fired at a firing temperature of greater than 1505°C and less than 1520°C for 5 hours to 120 hours. By firing in this temperature range, the Ti-rich phase region and the Sn-rich phase region can be formed into an island-like shape. The firing temperature is preferably 1510°C to 1515°C. The firing atmosphere is air, an oxygen atmosphere, or the like. An electric furnace, a millimeter wave furnace, an infrared furnace, or the like can be used for firing. The heating rate during heating is preferably 1°C / min to 30°C / min.

[0038] 5) Rapid cooling after firing After firing is complete, the material is removed from the furnace and rapidly cooled in air or water, resulting in a structure in which Ti-rich and Sn-rich phase regions are separated into island-like regions within the crystal grains.

[0039] [Embodiment 2] In embodiment 2, a ceramic capacitor including a ceramic body containing the dielectric ceramic according to embodiment 1 will be described. Ceramic capacitors include those that do not have internal electrodes inside the ceramic element (single-layer ceramic capacitors) and those that have multiple internal electrodes inside the ceramic element (multilayer ceramic capacitors). A single-layer ceramic capacitor corresponds to a multilayer ceramic capacitor without internal electrodes. Therefore, the multilayer ceramic capacitor will be mainly described with reference to the drawings.

[0040] 4 is a schematic cross-sectional view of the multilayer ceramic capacitor 110. The multilayer ceramic capacitor 110 includes a ceramic body 400 and external electrodes 310, 320 provided on both ends of the ceramic body 400.

[0041] The ceramic body 400 is composed of multiple ceramic layers 405. Internal electrodes 410, 420 are provided inside the ceramic body 400. The internal electrodes 410, 420 and the ceramic layers 405 are alternately stacked to form the ceramic body 400. The internal electrodes 410, 420 are exposed from one of the end faces of the ceramic body 400 and are electrically connected to the external electrodes 310, 320.

[0042] The ceramic layers 405 of the ceramic body 400 used in the multilayer ceramic capacitor 110 are formed from the dielectric ceramic according to embodiment 1. Therefore, the ceramic layers 405 have a high relative dielectric constant and a small dielectric loss tangent, making it possible to obtain a multilayer ceramic capacitor 110 with a large capacitance and little heat generation due to dielectric loss.

[0043] The materials of the external electrodes 310, 320 and internal electrodes 410, 420 used in the multilayer ceramic capacitor 110 and the method for manufacturing the multilayer ceramic capacitor 110 can be known external electrode and internal electrode materials and known multilayer ceramic capacitor manufacturing methods.

[0044] On the other hand, in a single-layer ceramic capacitor, a ceramic element body that does not include internal electrodes is used, and external electrodes are provided on both ends of the ceramic element body. The ceramic element body used in the single-layer ceramic capacitor is formed from the dielectric ceramic according to embodiment 1. This allows for a single-layer ceramic capacitor with large capacitance and little heat generation due to dielectric loss.

[0045] A) Preparation of Dielectric Sintered Body Samples TiO2, SnO2, and Nb2O5 were used as raw materials. Each raw material was weighed so that the Ti, Sn, and Nb contents satisfied the elemental content relationships shown in Table 1. An organic solvent such as ethanol was added, and the mixture was wet-mixed in a ball mill for a predetermined time. The dried and granulated powder was then calcined in air at 1100°C for 6 hours to obtain a solid solution. This powder was granulated and uniaxially pressed using a 10-mφ press at 20 MPa for 1 minute, followed by CIP treatment at 125 MPa for 1 minute to obtain a compact. This compact was then sintered in air at the firing temperatures shown in Table 1 for 24 hours to obtain a dense dielectric sintered body (hereinafter sometimes referred to as "sintered body"). The heating rate during sintering was 5°C / min, and the temperature was rapidly cooled in air.

[0046] B) Characterization (1) Measurement of the average dimensions of the Ti-rich and Sn-rich phase regions of the sintered compact sample. The sintered compact sample was embedded in resin, with the entire outer surface covered with epoxy resin. After the epoxy resin cured, the sample was mirror-polished along with the epoxy resin. Subsequently, sections of 80-1200 nm thick were cut using an FIB and subjected to platinum sputtering. The Ti, Sn, and Nb (atom%) contents within the sintered compact sample were measured using STEM-EDX. The STEM was observed at an accelerating voltage of 200 kV and a magnification of 60,000x (Figure 2). The distribution data for each element obtained from STEM-EDX (Figure 2) was image-processed and output as a 256 x 256 CSV file. Each cell contained the content (atom%) of each element at the measurement point corresponding to that cell's position. Using the Ti distribution data (a CSV file of the Ti content (atom %)) and the Sn distribution data (a CSV file of the Sn content (atom %)), the value of A at the measurement position corresponding to each cell was calculated using the following formula (1), and the value of B at the measurement position corresponding to each cell was calculated using the following formula (2): A = (Ti content (atom %)) / (total content of Ti and Sn (atom %)) (1) B = (Sn content (atom %)) / (total content of Ti and Sn (atom %)) (2)

[0047] Using spreadsheet software Excel (Microsoft Corporation), mapping data (Ti mapping data) in which the calculation result (A value) of formula (1) was entered in a range of 256 cells x 256 cells, and mapping data (Sn mapping data) in which the calculation result (B value) of formula (2) was entered in a range of 256 cells x 256 cells were created.

[0048] For the Ti mapping data, Excel borders were hidden and the text color in each cell was set to white. Furthermore, the Excel function "Conditional Formatting" was applied, and the background and text colors of cells with an A value of 0.55 or greater were set to the same color (e.g., red). After processing the data in this way, the 256 x 256 cell range containing the values ​​was saved as image data (JPEG file) (Figure 3).

[0049] Similarly, for the Sn mapping data, the Excel borders were hidden and the text color in each cell was set to white. Furthermore, the Excel function "Conditional Formatting" was applied to set the background and text colors of cells with a B value of 0.55 or greater to the same color (e.g., red). After processing the data in this way, the 256 x 256 cell range containing the values ​​was saved as image data (JPEG file) (Figure 3).

[0050] When the value of A is 0.55 or more (A≧0.55), the measurement position is determined to be a "Ti-rich phase," and when the value of B is 0.55 or more (B≧0.55), the measurement position is determined to be made up of a "Sn-rich phase." In other words, in Ti image data created by processing Ti mapping data, colored portions (e.g., red portions) indicate that the portion is a Ti-rich phase. Similarly, in Sn image data created by processing Sn mapping data, colored portions (e.g., red portions) indicate that the portion is a Sn-rich phase.

[0051] The Ti image data was read using image analysis software WinROOF (Mitani Corporation), the highest Ti detection intensity within the field of view was identified, and all regions with Ti detection intensities of 1 / 100 or less of that highest detection intensity (low Ti concentration regions) were identified. The Sn image data was analyzed in the same manner, and all regions with Sn detection intensities of 1 / 100 or less of the highest Sn detection intensity (low Sn concentration regions) were identified. Regions that were low Ti concentration regions and low Sn concentration regions were identified as "pores." The Ti image data was analyzed again, and a file (roi file) was created in which the portions excluding the pores were designated as the "region to be analyzed." The Sn image data was also analyzed again in the same manner, and an roi file was created.

[0052] In the ROI file of the Ti image, the clusters in the red areas were considered to be Ti-rich phase regions. The Ti-rich phase regions were island-shaped. 300 Ti-rich phase regions were randomly selected from the observation area, and the maximum dimension of each region (Ferret II diameter (horizontal)) was measured. The average value of the obtained maximum dimension measurement data (300 data) was referred to as the "average dimension D of the Ti-rich phase region." Ti (nm)".

[0053] Similarly, for the ROI file of the Sn image, the clusters in the red areas were considered to be Sn-rich phase regions. The Sn-rich phase regions also had an island-like structure. 300 Sn-rich phase regions were randomly selected from the observation area, and the maximum dimension of each region (Ferret II diameter (horizontal)) was measured. The average value of the maximum dimension measurement data (300 data) was defined as the "average dimension D of the Sn-rich phase region." Sn (nm)".

[0054] Furthermore, in the ROI file of the Ti image, the total area of ​​the Ti-rich phase regions (the sum of the areas of all Ti-rich phase regions included in the observation range) was calculated, and the area ratio of the total area of ​​the Ti-rich phase regions was calculated when the area of ​​the "region to be analyzed" was set to 100%. The measurement target was a Ti-rich phase region within the observation field of view with a maximum dimension of 14 nm or more. Ten ROI files of Ti images created from STEM-EDX measurement data measured at different positions were prepared, and the area ratio of the total area of ​​the Ti-rich phase regions was calculated for each file, and the average value was taken as the "area ratio α (%) of the Ti-rich phase regions."

[0055] (2) Composition analysis of dielectric sintered body The composition of the sintered body sample was analyzed using inductively coupled plasma atomic emission spectroscopy. A standard solution was used to quantify each element, and a calibration curve was created within the range of known concentrations to determine the relative concentration of the sample.

[0056] (3) Measurement of Electrical Properties After mirror polishing both surfaces of the sintered compact sample, electrodes were formed by sputtering, and the capacitance and dielectric loss tangent (dielectric loss) of the sintered compact sample were measured. The measurement method was in accordance with JIS C 5101-1:2019 (4.7.1) and JIS C 5101-1:2019 (4.8.1). However, the measurement frequency was 10 kHz. The relative dielectric constant of the sintered compact sample was calculated from the capacitance measurement results.

[0057] The evaluation criteria for electrical properties were as follows. In measurements at 10 kHz, a dielectric loss tangent of 0.035 or less and a relative dielectric constant of 2400 or more were evaluated as "pass (D)." Furthermore, a dielectric loss tangent of 0.030 or less and a relative dielectric constant of 2500 or more were evaluated as "C," a dielectric loss tangent of 0.025 or less and a relative dielectric constant of 2550 or more were evaluated as "B," and a dielectric loss tangent of 0.020 or less and a relative dielectric constant of 2600 or more were evaluated as "A." Note that a sample that did not satisfy at least one of the conditions of a dielectric loss tangent exceeding 0.035 and a relative dielectric constant less than 2400 was evaluated as "fail (F)."

[0058] The results of each measurement are shown in Table 1.

[0059]

[0060] Examples that satisfied all the requirements specified in the first embodiment were good in both dielectric constant and dielectric loss tangent, and were rated A to D. Furthermore, examples in which the area fraction α (%) of the Ti-rich phase region was 5.50% or more and 7.10% or less had better dielectric constant and dielectric loss tangent, and were rated C or higher. Furthermore, examples in which the area fraction α (%) was 5.50% or more and 6.80% or less and the average dimension D of the Ti-rich phase region was Ti In the examples where the average dimension D is 16 nm or more and 18 nm or less, the relative dielectric constant and the dielectric loss tangent are particularly good, and the examples are rated B or higher. Ti The examples in which the thickness was 16 nm or more and 17 nm or less had the best relative dielectric constant and dielectric loss tangent, and were rated A.

[0061] The comparative examples that did not satisfy one or more of the requirements defined in the first embodiment were rated F because one or more of the relative dielectric constant and the dielectric loss tangent were lower than the pass line.

[0062] The disclosure of the present specification may include the following aspects: <1> A ceramic material containing (Ti, x Sn 1-x )O2 (0.40≦x≦0.60), and further containing Nb, and in a cross-sectional view, the dielectric ceramic comprises: a region consisting of a Ti-rich phase in which A defined by the following formula (1) is 0.55 or more; and a region consisting of a Sn-rich phase in which B defined by the following formula (2) is 0.55 or more; and satisfies the following formulas (3) to (5): A=(Ti content (atom %)) / (total content of Ti and Sn (atom %)) (1) B=(Sn content (atom %)) / (total content of Ti and Sn (atom %)) (2) 0.005 mol%≦y≦0.020 mol% (3) 16 nm≦D Ti ≦20 nm (4) 15 nm≦D Sn ≦19 nm (5) where y (mol %) is the content of Nb when the content of the rutile compound is 100 mol %, and D Ti (nm) is the average size of the Ti-rich phase domain, and D Sn(nm) is the average size of the Sn-rich phase domains.

[0063] <2> The dielectric ceramic according to <1>, wherein, in a cross-sectional view, an area ratio α (%) of the Ti-rich phase region is 5.50% or more and 7.10% or less when an area ratio of the dielectric ceramic excluding pores is 100%.

[0064] <3> The dielectric ceramic according to <2>, wherein the area ratio α (%) is 5.50% or more and 6.80% or less.

[0065] <4> Average dimension D of the Ti-rich phase region Ti <1> to <3>, wherein the dielectric ceramic is 16 nm or more and 18 nm or less.

[0066] <5> Average dimension D of the Ti-rich phase region Ti <1> to <4>, wherein the dielectric ceramic is 16 nm or more and 17 nm or less.

[0067] <6> A ceramic capacitor comprising a ceramic body containing the dielectric ceramic according to any one of <1> to <5>.

[0068] <7> A multilayer ceramic capacitor comprising a ceramic body containing the dielectric ceramic according to any one of <1> to <5>.

[0069] This application claims priority based on Japanese Patent Application No. 2023-030206, filed on February 28, 2023, the entire contents of which are incorporated herein by reference.

[0070] REFERENCE SIGNS LIST 10 Dielectric ceramic 12 Crystal grain 14 Grain boundary 20 Ti-rich phase region 30 Sn-rich phase region 110 Multilayer ceramic capacitor 310, 320 External electrode 400 Ceramic element body 405 Ceramic layer 410, 402 Internal electrode

Claims

1. The main component is (Ti x Sn 1-x ) O 2 (0.40≦x≦0.60) and further containing Nb; In cross section, A region consisting of a Ti-rich phase in which A defined by the following formula (1) is 0.55 or more; A region consisting of a Sn-rich phase in which B defined by the following formula (2) is 0.55 or more, A dielectric ceramic that satisfies the following formulas (3) to (5). A = (Ti content (atom%)) / (Ti and Sn total content (atom%)) (1) B = (Sn content (atom%)) / (Total content of Ti and Sn (atom%)) (2) 0.005mol%≦y≦0.020mol% (3) 16nm≦D Ti ≦20nm (4) 15nm≦D Sn ≦19nm (5) Where: y (mol%) is the Nb content when the content of the rutile compound is 100 mol%, D Ti (nm) is the average size of the Ti-rich phase domains; D Sn (nm) is the average size of the Sn-rich phase domains.

2. 2. The dielectric ceramic according to claim 1, wherein, in a cross-sectional view, an area ratio α (%) of the Ti-rich phase region is 5.50% or more and 7.10% or less when an area ratio of the dielectric ceramic excluding pores is 100%.

3. The dielectric ceramic according to claim 2, wherein the area ratio α (%) is 5.50% or more and 6.80% or less.

4. The average dimension D of the Ti-rich phase region Ti The dielectric ceramic according to claim 1, wherein the average particle diameter is 16 nm or more and 18 nm or less.

5. The average dimension D of the Ti-rich phase region Ti The dielectric ceramic according to claim 1, wherein the average particle diameter is 16 nm or more and 17 nm or less.

6. A ceramic capacitor comprising a ceramic body containing the dielectric ceramic according to any one of claims 1 to 5.

7. A multilayer ceramic capacitor comprising a ceramic body containing the dielectric ceramic according to any one of claims 1 to 5.