Oxide sinter

Abstract

The present application relates to an oxide sintered body. The oxide sintered body, which comprises zinc, magnesium, a metal element X and oxygen as constituent elements, the metal element X being +3 valence or +4 valence, the atomic ratio of the metal element X to the total of zinc, magnesium and the metal element X [X / (Zn+Mg+X)] being 0.0001 or more and 0.6 or less, and the atomic ratio of magnesium to the total of zinc and magnesium [Mg / (Zn+Mg)] being 0.25 or more and 0.8 or less.

Description

Technical Field

[0001] This application is a divisional application of PCT application No. 202080046931.9 (international filing date: June 24, 2020) entitled "Oxide Sintered Body", which has entered the national phase.

[0002] This invention relates to oxide sintered bodies and film-forming materials for forming thin films. Background Technology

[0003] Examples of applications of MgO-ZnO oxides include transparent ceramics for color liquid crystal projectors (Patent Document 1), oxide semiconductors (Patent Document 2), and transparent electrodes (Patent Document 3). For example, Patent Document 3 discloses a sintered body with an atomic ratio of Al / (Zn+Al+Mg) = 0.005 to 0.1 and Mg / (Zn+Al+Mg) = 0.001 to 0.05, comprising: (a) hexagonal wurtzite-type particles containing zinc oxide and having an average particle size of 10 μm or less, and (b) spinel-type particles containing aluminum and having an average particle size of 5 μm or less.

[0004] The sintered body mentioned above is a material that emphasizes electrical conductivity, but since it is mainly composed of ZnO, there is a problem with its light transmittance in the ultraviolet region.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2009-184898

[0008] Patent Document 2: Japanese Patent Application Publication No. 2012-066968

[0009] Patent document 3: Japanese Patent Application Publication No. 2011-063866. Summary of the Invention

[0010] One of the objectives of this invention is to provide an oxide sintered body capable of producing a film with high light transmittance and high conductivity in the ultraviolet region.

[0011] The inventors have discovered that by sintering oxides containing trivalent or tetravalent metal elements at specific concentrations in Mg and Zn oxides and forming them into films, it is possible to obtain films with high transmittance and good conductivity in the ultraviolet region.

[0012] According to the present invention, the following oxide sintered bodies, etc., are provided.

[0013] 1. An oxide sintered body comprising zinc, magnesium, metal element X and oxygen as constituent elements, wherein the metal element is valence trivalent or valence tetravalent, and the atomic ratio of the aforementioned metal element X relative to the aforementioned zinc, the aforementioned magnesium and the aforementioned metal element X total [X / (Zn+Mg+X)] is 0.0001 or more and 0.6 or less, and the atomic ratio of the aforementioned magnesium relative to the aforementioned zinc and the aforementioned magnesium total [Mg / (Zn+Mg)] is 0.25 or more and 0.8 or less.

[0014] 2. The oxide sintered body according to claim 1, wherein the aforementioned atomic ratio [Mg / (Zn+Mg)] is 0.625 or more and 0.8 or less.

[0015] 3. The oxide sintered body according to claim 1, wherein the aforementioned atomic ratio [Mg / (Zn+Mg)] is 0.626 or more and 0.75 or less.

[0016] 4. The oxide sintered body according to claim 1, wherein the aforementioned atomic ratio [Mg / (Zn+Mg)] is 0.628 or more and 0.74 or less.

[0017] 5. The oxide sintered body according to any one of 2 to 4, comprising cubic MgO with Zn dissolved in it and MgX2O4 with Zn dissolved in it (X is a metal element with a positive valence of +3).

[0018] 6. The oxide sintered body according to claim 1, wherein the aforementioned atomic ratio [Mg / (Zn+Mg)] is 0.25 or more and less than 0.625.

[0019] 7. The oxide sintered body according to claim 1, wherein the aforementioned atomic ratio [Mg / (Zn+Mg)] is 0.30 or more and 0.60 or less.

[0020] 8. The oxide sintered body according to claim 1, wherein the aforementioned atomic ratio [Mg / (Zn+Mg)] is 0.40 or more and 0.59 or less.

[0021] 9. The oxide sintered body according to any one of 6 to 8, comprising cubic MgO with Zn dissolved in it, hexagonal ZnO with Mg dissolved in it, and MgX2O4 with Zn dissolved in it (here, X is a metal element with a positive valence of +3).

[0022] 10. The oxide sintered body according to any one of 1 to 9, wherein the aforementioned atomic ratio [X / (Zn+Mg+X)] is 0.003 or more and 0.6 or less.

[0023] 11. The oxide sintered body according to any one of 1 to 9, wherein the aforementioned atomic ratio [X / (Zn+Mg+X)] is 0.007 or more and 0.5 or less.

[0024] 12. The oxide sintered body according to any one of 1 to 9, wherein the aforementioned atomic ratio [X / (Zn+Mg+X)] is 0.008 or more and 0.5 or less.

[0025] 13. The oxide sintered body according to any one of 1 to 9, wherein the aforementioned atomic ratio [X / (Zn+Mg+X)] is 0.01 or more and 0.5 or less.

[0026] 14. The oxide sintered body according to any one of 1 to 13, wherein the aforementioned X is at least one of Al and Ga.

[0027] 15. The oxide sintered body according to 14, wherein the aforementioned X is Al.

[0028] 16. The oxide sintered body according to 14, wherein the aforementioned X is Ga.

[0029] 17. A film-forming material comprising any one of the oxide sintered bodies described in 1 to 16.

[0030] 18. The film-forming material according to 17 is a film-forming plate.

[0031] 19. The film-forming material according to 17 is a sputtering target.

[0032] 20. A thin film obtained using any one of the film-forming materials described in any one of 17 to 19.

[0033] According to the present invention, an oxide sintered body can be provided that can obtain a film with high light transmittance and high conductivity in the ultraviolet region. Attached Figure Description

[0034] Figure 1 This is a graph showing the analysis results of the XRD pattern of the oxide sintered body of Example 1.

[0035] Figure 2 This is a graph showing the analysis results of the XRD pattern of the oxide sintered body of Example 2.

[0036] Figure 3 This is a graph showing the analytical results of the XRD pattern of the oxide sintered body of Comparative Example 1.

[0037] Figure 4 This is a graph showing the analysis results of the XRD pattern of the oxide sintered body of Example 7.

[0038] Figure 5 This is a graph showing the analysis results of the XRD pattern of the oxide sintered body of Example 8.

[0039] Figure 6This is a graph showing the analytical results of the XRD pattern of the oxide sintered body of Comparative Example 2. Detailed Implementation

[0040] In one embodiment of the present invention, the oxide sintered body comprises zinc (Zn), magnesium (Mg), a metallic element (X), and oxygen (O) as constituent elements, wherein the metallic element (X) has a valence of +3 or +4. Furthermore, the atomic ratio [X / (Zn+Mg+X)] is 0.0001 or more and 0.6 or less, and the atomic ratio [Mg / (Zn+Mg)] is 0.25 or more and 0.8 or less.

[0041] In this embodiment, the metallic element X, which has a +3 or +4 valence, can be exemplified by Al, Ga, In, Sc, and Y. Al and / or Ga are preferred, and Al is more preferred. By including Al, the relative density of the oxide sintered body is increased. A high relative density means fewer voids that could be the cause of abnormal discharges during film formation and the starting point for nodule formation. Therefore, for example, when the oxide sintered body is used as a sputtering target, fewer cracks occur during sputtering, and sputtering can be stable.

[0042] The atomic ratio [X / (Zn+Mg+X)] is 0.0001 or higher and 0.6 or lower. By satisfying this range, an oxide sintered body is formed that can form a film that balances light transmittance and electrical conductivity in the ultraviolet region.

[0043] The atomic ratio [X / (Zn+Mg+X)] can be greater than 0.006, greater than 0.007, greater than 0.008, or greater than 0.01. Furthermore, the atomic ratio [X / (Zn+Mg+X)] can be less than 0.5, less than 0.2, or less than 0.1.

[0044] The atomic ratio [Mg / (Zn+Mg)] is 0.25 or higher and 0.8 or lower. By satisfying this range, an oxide sintered body can be formed that can achieve both ultraviolet transmittance and conductivity. It should be noted that when the atomic ratio exceeds 0.8, even if the film obtained from the oxide sintered body is annealed, a film with high conductivity cannot be obtained. On the other hand, when it is less than 0.25, the ultraviolet transmittance of the film becomes low.

[0045] In one embodiment, the atomic ratio [Mg / (Zn+Mg)] is 0.625 or higher and 0.8 or lower. By satisfying this range, the oxide sintered body is primarily capable of producing a film with excellent light transmittance in the ultraviolet region.

[0046] The atomic ratio [Mg / (Zn+Mg)] can be 0.626 or higher, or 0.628 or higher. Furthermore, the atomic ratio [Mg / (Zn+Mg)] can be 0.75 or lower, 0.70 or lower, or 0.67 or lower.

[0047] In one embodiment, the atomic ratio [Mg / (Zn+Mg)] is 0.25 or higher and less than 0.625. By satisfying this range, it becomes primarily an oxide sintered body capable of producing films with excellent electrical conductivity.

[0048] The atomic ratio [Mg / (Zn+Mg)] can be 0.30 or higher, or 0.40 or higher. Furthermore, the atomic ratio [Mg / (Zn+Mg)] can be 0.60 or lower, or 0.55 or lower.

[0049] The atomic ratios of zinc, magnesium, and metal element X can be controlled by adjusting the atomic ratios of the starting materials. Compared to the atomic ratios of the starting materials, the atomic ratios of oxide sinters tend to be higher for zinc and roughly the same for metal element X.

[0050] The atomic ratios of the elements contained in the oxide sintered body can be determined by analyzing the elements using an inductively coupled plasma optical emission spectrometry (ICP-AES) system. Specifically, when the solution sample is atomized using a nebulizer and introduced into an argon plasma (approximately 5000–8000°C), the elements in the sample absorb thermal energy and are excited. Orbital electrons transfer from the base state to higher energy orbitals and then to lower energy orbitals. This energy difference is emitted as light. This light displays the inherent wavelength (spectral lines) of the elements; therefore, the presence or absence of spectral lines can confirm the element's presence (qualitative analysis). Furthermore, the magnitude of the spectral lines (luminescence intensity) is proportional to the number of elements in the sample; therefore, the sample concentration can be determined by comparing it with a standard solution of known concentration (quantitative analysis). After determining the contained elements through qualitative analysis, the content is determined through quantitative analysis, and the atomic ratio of each element is calculated from the results.

[0051] The constituent elements of the oxide sintered body in this embodiment can be substantially composed of Mg, Zn, metallic element X, and O. For example, 70 mol% or more, 80 mol% or more, or 90 mol% or more of the constituent elements of the oxide sintered body in this embodiment can be Mg, Zn, metallic element X, and O. Furthermore, the constituent elements of the oxide sintered body in this embodiment can be solely composed of Mg, Zn, metallic element X, and O. In this case, unavoidable impurities may be present.

[0052] When the atomic ratio [Mg / (Zn+Mg)] is 0.625 or higher and 0.8 or lower, the oxide sintered body comprises cubic MgO with Zn dissolved in it and MgX₂O₄ with Zn dissolved in it (where X is a metal element with a +3 valence). Furthermore, when the atomic ratio [Mg / (Zn+Mg)] is 0.25 or higher and less than 0.625, the oxide sintered body comprises cubic MgO with Zn dissolved in it, hexagonal ZnO with Mg dissolved in it, and MgX₂O₄ with Zn dissolved in it (here, X is a metal element with a +3 valence). Thus, even with relatively light metal oxides, high-density sintered bodies can be obtained.

[0053] The presence of the aforementioned oxides in the oxide sintered body can be confirmed by comparing the XRD pattern obtained using X-ray diffraction (XRD) with the database of ICDD (International Center for Diffraction Data) (PDF: Powder Diffraction File). Furthermore, the presence of other metallic elements dissolved in the crystals can be determined by comparing the lattice constants (measured values) obtained using XRD with the lattice constants (PDF values) recorded in the PDF. For example, in the case of crystals containing dissolved Zn, the measured value is greater than the PDF value.

[0054] The oxide sintered body of this embodiment can be manufactured by, for example, the following steps: a step of mixing raw material powders to prepare a mixed powder, a step of molding the mixed powder to form a molded body, and a step of firing the molded body.

[0055] As starting materials, powders of compounds containing Mg, powders of compounds containing Zn, and powders of compounds containing metallic element X can be used. The compounds are preferably oxides. Examples include MgO, ZnO, Al₂O₃, and Ga₂O₃.

[0056] The mixing ratio of the raw material powders can be adjusted, for example, by taking into account the atomic ratio of the desired oxide sintered body.

[0057] The average particle size of the raw material powder is preferably 0.1–1.2 μm, more preferably 0.5–1.0 μm. The average particle size of the raw material powder can be measured using a laser diffraction particle size distribution device or the like.

[0058] There are no particular limitations on the mixing and molding methods of the raw materials; known methods can be used. In addition, a binder may be added during mixing.

[0059] The raw materials can be mixed using known equipment such as ball mills, bead mills, jet mills, or ultrasonic devices. The mixing time can be adjusted appropriately, preferably around 6 to 100 hours.

[0060] In molding methods, for example, mixed powders can be pressurized to form a molded body. Through this process, it is possible to mold it into the shape of an article (e.g., a shape suitable for a sputtering target).

[0061] The mixed powder is filled into a mold, typically using mold pressure or cold isostatic pressing (CIP), at a pressure of, for example, 1000 kg / cm². 2 The above process involves applying pressure, which yields the molded object.

[0062] It should be noted that molding aids such as polyvinyl alcohol, polyethylene glycol, methylcellulose, polywax, oleic acid, and stearic acid can be used during molding.

[0063] The resulting molded body is heated at a temperature of, for example, 1200–1650°C for more than 2 hours to obtain an oxide sintered body.

[0064] The heating temperature is preferably 1350–1600℃, more preferably 1400–1600℃, and even more preferably 1450–1500℃. The heating time is preferably 2–72 hours, more preferably 3–48 hours, and even more preferably 4–24 hours.

[0065] During firing, the molded body is typically heated in an atmospheric or oxygen atmosphere. An oxygen atmosphere with an oxygen concentration of, for example, 10 to 50% by volume is preferred.

[0066] The oxide sintered body of this embodiment can be suitably used as a film-forming material for forming thin films having an oxide sintered body composition, such as a flat plate or sputtering target used in film formation by vacuum evaporation or ion plating. The thin film obtained from the film-forming material of this embodiment can be used as a transparent conductive film in the electrode substrate of ultraviolet light-emitting diodes, ultraviolet light-emitting laser diodes, etc.

[0067] It should be noted that by heat-treating the film at high temperature after film formation, the ultraviolet transmittance and conductivity of the film are improved. The freshly formed film exhibits a uniform mixture of zinc oxide and magnesium oxide. By heat-treating this film, the oxides aggregate and separate. The results suggest that the zinc oxide forms a network, resulting in conductivity; conversely, the magnesium oxide aggregates within the gaps in the zinc oxide network, allowing ultraviolet light to pass through.

[0068] The heat treatment temperature of the electrode layer is preferably 750°C or higher, and more preferably 900°C or higher.

[0069] The flat plate can be manufactured, for example, by cutting or grinding an oxide sintered body obtained by shaping raw materials into a desired shape and firing it. The sputtering target can be manufactured, for example, by cutting or grinding an oxide sintered body and bonding it to a backing plate.

[0070] Uneven surfaces can be removed by cutting. Furthermore, it can be manufactured to specified sizes. The surface can be ground to #200, #400, or even #800 grit. This helps suppress abnormal discharge and particle generation during sputtering.

[0071] After cleaning the ground oxide sintered body as needed, the bonding surface is coated with bonding materials such as indium solder and bonded to the back plate to obtain a sputtering target.

[0072] Example

[0073] Example 1

[0074] (A) Fabrication of oxide sintered bodies

[0075] Zinc oxide (ZnO) powder with an average particle size of less than 1 μm, magnesium oxide (MgO) powder with an average particle size of less than 1 μm, and gallium oxide (Ga2O3) powder with an average particle size of less than 1 μm were weighed and mixed according to the atomic ratios of each metal shown in Table 1. It should be noted that the mass fractions of the mixed powders are: ZnO 43.9% by mass, MgO 40.8% by mass, and Ga2O3 15.3% by mass.

[0076] After adding the mixed powder to the resin mixing pot, water was added, and a wet ball mill was used to mix for 20 hours using hard ZrO2 balls as the grinding medium. The resulting slurry was then removed, filtered, dried, and granulated. The resulting granules were then placed in a mold and pressurized to 3 tons / cm² using cold isostatic pressing. 2 Then, it is shaped.

[0077] The resulting molded body was placed inside a sintering furnace, with the edges angled at 0.1 m intervals. 3 Oxygen is introduced into the furnace at a rate of 5L / min to fire the molded body.

[0078] The temperature inside the sintering furnace was increased from room temperature to 1000℃ at a rate of 1℃ / min, then increased from 1000℃ to 1470℃ at a rate of 3℃ / min, and sintered at 1470℃ for 5 hours. Afterward, oxygen supply was stopped, and the furnace temperature was decreased from 1470℃ to 1300℃ at a rate of 10℃ / min. Then, the temperature was increased at a rate of 0.1m... 3 Ar was fed into the furnace at a rate of 10 L / min, while the furnace temperature was maintained at 1300 °C for 3 hours. Subsequently, the oxide sintered body was obtained by natural cooling.

[0079] The composition and relative density of the obtained oxide sintered bodies were evaluated. The results are shown in Table 2.

[0080] [Table 1]

[0081]

[0082] [Table 2]

[0083]

[0084] The evaluation method is as follows.

[0085] (1) Atomic ratio of metal elements in oxide sintered bodies

[0086] A portion of the obtained oxide sintered body was cut off, dissolved in acid, and then analyzed using an inductively coupled plasma light luminescence analyzer.

[0087] (2) Relative density

[0088] The relative density is calculated as follows: the actual density of the oxide sintered body is determined using the Archimedes method with water and divided by the theoretical density calculated from the composition. It should be noted that the theoretical density is calculated from the mass fractions of oxygen-free MgO crystals, Zn oxide, and X (Ga or Al) oxide.

[0089] (3) XRD determination

[0090] The determination was carried out using the following apparatus and conditions.

[0091] • Apparatus: Rigaku Corporation's Ultima-III

[0092] X-rays: Cu-Kα rays (wavelength: Monochromaticization using a graphite monochromator

[0093] • 2θ-θ reflection method, continuous scanning (1.0° / minute)

[0094] • Sampling interval: 0.02°

[0095] • Slit DS, SS: 2 / 3°, RS: 0.6mm.

[0096] The crystal structure and lattice constant of the oxide sintered body were determined by analyzing the XRD results using integrated powder X-ray analysis software (RIGAG, PDXL2). It should be noted that the crystal structure was confirmed using the ICDD (PDF) card described below.

[0097] ZnO: 01-079-0205 (hexagonal crystal)

[0098] ZnO: 01-077-0191 (cubic crystal)

[0099] MgO: 01-071-1176 (cubic crystal)

[0100] MgAl2O4: 01-084-0377

[0101] MgGa2O4: 01-073-1721.

[0102] Figure 1 The results of the XRD pattern analysis are shown below. Figure 1 It can be confirmed that the oxide sintered body contains ZnO, MgO and MgGa2O4 as a crystal structure.

[0103] The presence of Zn-dissolved MgO and Zn-dissolved MgX2O4 (X = Ga or Al) was evaluated based on measured values ​​of lattice constant and PDF values.

[0104] The measured lattice constant α for MgO is 4.2314, and the PDF value is 4.217. The measured lattice constant α for ZnO is 3.2423, and the PDF value is 3.242. The measured lattice constant α for MgGa₂O₄ is 8.3116, and the PDF value is 8.26. These results confirm that the difference in lattice constant α between MgO and MgGa₂O₄ is large, indicating the presence of Zn dissolved in these crystals. It should be noted that a change in lattice constant greater than 0.01 is considered a solid solution.

[0105] The results are shown in Table 3. In the table, ○ is used to indicate inclusion and × is used to indicate exclusion.

[0106] [Table 3]

[0107]

[0108] (B) Sputtering target fabrication

[0109] The resulting oxide sintered body is ground using a cup-grinding stone to form a diameter of 100 mm and a thickness of 5 mm. An In-based alloy is then used to attach a backing plate to the ground oxide sintered body to fabricate the sputtering target.

[0110] Thin films were actually formed using a sputtering target made of oxide sintered body, and the results were evaluated. The film formation conditions are shown below.

[0111] The sapphire substrate (0.5 mm thick) was placed in an ultrasonic cleaner and cleaned with trichloroethylene for 5 minutes, acetone for 5 minutes, methanol for 5 minutes, and finally, distilled water for 5 minutes.

[0112] The substrate was placed in a sputtering apparatus (ULVAC: ACS-4000) and sputtered with Ar gas at 25°C to form a film with a thickness of 100 nm on the substrate.

[0113] (2) Heat treatment

[0114] For the substrate with the film formed by (1) above, heat treatment was performed at 950°C for 5 minutes in a nitrogen atmosphere (activation annealing). The surface resistivity of the heat-treated film was measured using a LORESTA FP manufactured by Mitsubishi Chemical Corporation. In addition, the ultraviolet transmittance was evaluated using a spectrophotometer (Shimadzu Corporation: UV-2600).

[0115] The evaluation results are shown in Table 4.

[0116] [Table 4]

[0117] Ultraviolet transmittance (%) Resistance (Ωcm) Example 1 30 100 Example 2 30 100 Example 3 40 <![CDATA[1×10 4 ]]> Example 4 20 1 Example 5 20 100 Example 6 20 1000 Comparative Example 1 35 <![CDATA[1×10 5 ]]>

[0118] Examples 2-6, Comparative Example 1

[0119] The raw materials were weighed and mixed according to the atomic ratios of the various metal elements shown in Table 1. Otherwise, the same procedures as in Example 1 were followed to prepare the oxide sintered body and sputtering target, and the results were evaluated. The results are shown in Tables 2-4. It should be noted that in the examples where metal element X was Al, alumina (Al₂O₃ powder) with an average particle size of less than 1 μm was used.

[0120] Figure 2 The XRD pattern analysis results of the oxide sintered body of Example 2 are shown in the figure. Figure 3 The XRD pattern analysis results of the oxide sintered body of Comparative Example 1 are shown in the figure.

[0121] Example 7

[0122] (A) Fabrication of oxide sintered bodies

[0123] Zinc oxide (ZnO) powder with an average particle size of less than 1 μm, magnesium oxide (MgO) powder with an average particle size of less than 1 μm, and gallium oxide (Ga2O3) powder with an average particle size of less than 1 μm were weighed and mixed according to the atomic ratios of each metal shown in Table 5. It should be noted that the mass fractions of the mixed powders are: ZnO 48.9% by mass, MgO 36.3% by mass, and Ga2O3 14.8% by mass.

[0124] After adding the mixed powder to the resin mixing pot, water was added, and a wet ball mill was used to mix for 20 hours using hard ZrO2 balls as the grinding medium. The resulting slurry was then removed, filtered, dried, and granulated. The resulting granules were then placed in a mold and pressurized to 3 tons / cm² using cold isostatic pressing. 2 Then, it is shaped.

[0125] The resulting molded body was placed inside a sintering furnace, with the edges angled at 0.1 m intervals. 3Oxygen is introduced into the furnace at a rate of 5L / min to fire the molded body.

[0126] The temperature inside the sintering furnace was increased from room temperature to 1000℃ at a rate of 1℃ / min, and then increased from 1000℃ to 1470℃ at a rate of 3℃ / min, and sintered at 1470℃ for 5 hours. Afterwards, oxygen supply was stopped, and the furnace temperature was decreased from 1470℃ to 1300℃ at a rate of 10℃ / min. Then, the temperature was increased at a rate of 0.1m... 3 Ar was fed into the furnace at a rate of 10 L / min, while the furnace temperature was maintained at 1300 °C for 3 hours. Subsequently, the oxide sintered body was obtained by natural cooling.

[0127] The composition and relative density of the resulting oxide sintered body were evaluated using the same procedure as in Example 1. The results are shown in Table 6.

[0128] [Table 5]

[0129]

[0130] [Table 6]

[0131]

[0132] Figure 4 The results of the XRD pattern analysis are shown below. Figure 4 It can be confirmed that the oxide sintered body contains ZnO (hexagonal), MgO (cubic), MgGa2O4, and Ga2O3(ZnO)6 as its crystal structure. It should be noted that the presence of Ga2O3(ZnO)6 is inferred due to poor fitting accuracy.

[0133] The presence of Zn-dissolved MgO (cubic), ZnO (hexagonal), and Zn-dissolved MgX2O4 (X = Ga or Al) was evaluated based on measured values ​​of lattice constant and PDF values.

[0134] The lattice constant α for MgO is 4.2307 (measured value) and 4.217 (PDF value). The lattice constant α for ZnO is 3.2482 (measured value) and 3.242 (PDF value). The lattice constant α for MgGa₂O₄ is 8.3121 (measured value) and 8.26 (PDF value). Thus, due to the change in lattice constant, it is determined that Mg is dissolved in ZnO. Furthermore, Zn is dissolved in both MgO and MgGa₂O₄.

[0135] The results are shown in Table 7. In the table, ○ is used to indicate inclusion and × is used to indicate exclusion.

[0136] [Table 7]

[0137]

[0138] (B) Sputtering target fabrication

[0139] Except for using the oxide sintered body of Example 7, the sputtering target was fabricated and evaluated in the same manner as in Example 1. The results are shown in Table 8.

[0140] [Table 8]

[0141] Ultraviolet transmittance (%) Resistance (Ωcm) Example 7 12 0.001 Example 8 12 0.05 Comparative Example 2 15 1000 Example 9 10 0.001 Example 10 18 0.1 Example 11 18 1 Example 12 18 0.5 Example 13 18 0.05

[0142] Examples 8-13, Comparative Example 2

[0143] The raw materials were weighed and mixed according to the atomic ratios of the various metal elements shown in Table 5. Otherwise, the same procedures as in Example 7 were followed to prepare the oxide sintered body and sputtering target, and the results were evaluated. The results are shown in Tables 6-8. It should be noted that in the examples where metal element X was Al, alumina (Al₂O₅ powder) with an average particle size of less than 1 μm was used.

[0144] Figure 5 The XRD pattern analysis results of the oxide sintered body of Example 8 are shown in the figure. Figure 6 The XRD pattern analysis results of the oxide sintered body of Comparative Example 2 are shown in the figure.

[0145] In summary, several embodiments and / or examples of the present invention have been described in detail. However, those skilled in the art can readily make various modifications to these illustrated embodiments and / or examples without substantially departing from the new teachings and effects of the present invention. Therefore, these various modifications are included within the scope of the present invention.

[0146] The contents of the document described in this specification and the application that forms the basis of this application based on the priority of the Paris Convention are hereby cited in their entirety.

Claims

1. An oxide sintered body comprising zinc, magnesium, a metallic element X and oxygen as constituent elements, wherein the metallic element X is at least one of Al and Ga; The atomic ratio of the metal element X relative to the zinc, magnesium, and the total of the metal element X, X / (Zn+Mg+X), is 0.003 or more and 0.100 or less. The atomic ratio of Mg / (Zn+Mg) is greater than 0.536 and less than 0.

625. It includes cubic MgO with Zn dissolved in it, hexagonal ZnO with Mg dissolved in it, and MgX2O4 with Zn dissolved in it, where X is a metallic element with a positive trivalent valence.

2. The oxide sintered body according to claim 1, wherein, The atomic ratio Mg / (Zn+Mg) is greater than 0.536 and less than 0.

60.

3. The oxide sintered body according to claim 1, wherein, The atomic ratio Mg / (Zn+Mg) is greater than 0.536 and less than 0.

59.

4. The oxide sintered body according to any one of claims 1 to 3, wherein, The atomic ratio X / (Zn+Mg+X) is greater than 0.007 and less than 0.

100.

5. The oxide sintered body according to any one of claims 1 to 3, wherein, The atomic ratio X / (Zn+Mg+X) is greater than 0.008 and less than 0.

100.

6. The oxide sintered body according to any one of claims 1 to 3, wherein, The atomic ratio X / (Zn+Mg+X) is greater than 0.01 and less than 0.

100.

7. The oxide sintered body according to any one of claims 1 to 3, wherein, The atomic ratio X / (Zn+Mg+X) is greater than 0.003 and less than 0.

095.

8. The oxide sintered body according to any one of claims 1 to 3, wherein, The atomic ratios of the elements contained in the oxide sintered body are determined by analyzing the contained elements using an inductively coupled plasma optical emission spectrometer (ICP-AES).

9. The oxide sintered body according to claim 1, wherein, X is Al.

10. The oxide sintered body according to claim 1, wherein, X is Ga.

11. The oxide sintered body according to any one of claims 1 to 3, wherein, The constituent elements of the oxide sintered body are Mg, Zn, metallic elements X and O, accounting for more than 90 mol% of the total constituent elements.

12. The oxide sintered body according to any one of claims 1 to 3, wherein, Apart from unavoidable impurities, the constituent elements of the oxide sintered body are only Mg, Zn, metallic element X and O.

13. A film-forming material comprising any one of claims 1 to 12.

14. The film-forming material according to claim 13, wherein it is a film-forming plate.

15. The film-forming material according to claim 14, wherein it is a sputtering target.

16. A thin film obtained using the film-forming material according to any one of claims 13 to 15.

17. A transparent conductive film comprising the thin film of claim 16.

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