Novel composite oxide

Abstract

The present invention relates to a composite oxide represented by general formula (1): CaxZn2 − xP2O7 ± δ (In the formula, some of the Ca may be substituted by Sr and / or Ba and / or Mg, or all of the Ca may be substituted by Sr and / or Ba. In the formula, 0 < x < 2, and δ is a value determined so as to satisfy a charge neutrality condition.). The composite oxide may be a negative-thermal-expansion material having a temperature zone in which the linear expansion coefficient (α) is less than 0 ppm / K in at least a temperature range of 0-140°C.

Description

Novel composite oxide

[0001] The present invention relates to a novel composite oxide represented by a specific formula containing at least one element selected from the group consisting of Ca, Sr, Ba, and Mg, and Zn and P, which preferably exhibits negative thermal expansion characteristics.

[0002] In recent years, in technical fields that require high precision such as highly developed electronic devices, optical devices, fuel cells, and sensors, control and suppression of the thermal expansion of solid materials have been strongly demanded. In particular, when constructing precision devices such as semiconductor devices that require high precision at the nanometer level by combining multiple materials, differences in the thermal expansion coefficients between the materials can cause problems such as displacement, interfacial delamination, disconnection, warping, and cracking, which may become serious issues. Therefore, technologies for highly controlling thermal expansion are required.

[0003] While many substances thermally expand with an increase in temperature, it is also known that negative thermal expansion materials with a negative thermal expansion coefficient, which have the property of decreasing in volume with an increase in temperature, are rarely present. As one of the technologies for controlling the thermal expansion of precision devices, for example, a technology for controlling the thermal expansion coefficient of the entire device by adding a negative thermal expansion material in combination with a matrix material (resin, glass, metal, etc.) having a large positive thermal expansion coefficient and, if necessary, a material having a low positive thermal expansion coefficient (e.g., silica) has attracted attention. Examples of negative thermal expansion materials include β-eucryptite, zirconium tungstate (ZrW ２ O ８ ), zirconium tungstophosphate (Zr ２ WO ４ (PO ４ ), Zn ２ Cd ｘ (CN １－ｘ ), manganese nitride, bismuth nickel ferrite, etc. are known. ２

[0004] For example, in Patent Document 1, zirconium oxide ZrO ３ with respect to tungsten trioxide WO ２The negative thermal expansion material Zr is characterized by mixing raw materials in a stoichiometric ratio such that the sum of the substitution element X with the substitution amount x is 1 molar ratio, forming a powder with a polarized particle size distribution consisting of small particles with a predetermined particle size range and large particles with a predetermined particle size range, and then placing the raw material powder into a desired mold and sintering it. （１－ｘ） X ｘ W ２ O ８ A method for synthesizing (where X is a substitution element for zirconium Zr, 0 ≤ x << 1) has been reported. Patent Document 1 states that this synthesis method has the effect of synthesizing large, high-density heat-shrinkable ceramics without press molding of the raw material powder. In addition to Patent Document 1, development is underway on new negative thermal expansion materials with various compositions and properties, as well as methods for manufacturing them.

[0005] For example, Patent Document 2 reports a negative thermal expansion material containing an oxide represented by a general formula that includes at least one element selected from Mg, Al, Zn, etc., and / or Cu, V, and P. Patent Document 3 reports a lead sealing glass and magnesium pyrophosphate (Mg ２ P ２ O ７ Mill additives of pyrophosphate crystalline materials consisting of ) particularly MgO and P present in approximately stoichiometric molar ratios of magnesium pyrophosphate. ２ O ５ A sealing material having a negative coefficient of thermal expansion has been reported, which includes crystallized glass that is essentially made from. Patent Document 4 describes a material that is substantially P ２ O ５ Negative thermal expansion materials consisting of crystalline phosphate glass particles with one cation selected from magnesium, zinc, aluminum, etc., and mixtures of organic polymers have been reported. Patent document 5 reports modified zirconium tungstate phosphate, which is a negative thermal expansion material whose surface is coated with an inorganic compound containing one or more elements selected from Zn, Mg, V, etc., and it is shown that the amount of phosphorus ions eluting from modified zirconium tungstate phosphate under predetermined conditions can be suppressed by such surface modification.

[0006] Japanese Patent Publication No. 2003-342075, International Publication No. 2022 / 114004, U.S. Patent No. 5089445, Japanese Patent Publication No. Hei 08-048809, Japanese Patent Publication No. 2020-147486

[0007] For example, in precision equipment such as semiconductor devices that require high-precision thermal expansion control, the actual operating temperature during the heat cycle of the equipment is often below 150°C. Therefore, there is a need for materials that exhibit negative thermal expansion characteristics in such temperature ranges. However, many conventional negative thermal expansion materials only exhibit negative thermal expansion characteristics when they reach temperatures above 150°C. Consequently, research is ongoing to find specific compositions of negative thermal expansion materials that exhibit negative thermal expansion characteristics in lower temperature ranges, such as below 150°C, and preferably achieve a higher thermal contraction rate (i.e., a lower negative thermal expansion rate).

[0008] Therefore, the object of the present invention is to provide a novel composite oxide that exhibits negative thermal expansion characteristics in a lower temperature range and can be used as a negative thermal expansion material with a preferably higher thermal shrinkage coefficient.

[0009] As a result of diligent research, the inventors have discovered that a composite oxide represented by a specific formula containing at least one element selected from the group consisting of Ca, Sr, Ba, and Mg, along with Zn and P, can often be used as a negative thermal expansion material that exhibits negative thermal expansion characteristics in a lower temperature range and preferably has a higher thermal shrinkage coefficient, thus completing the present invention.

[0010] In other words, one aspect of the present invention for solving the above problem is the general formula (1) Ca ｘ Zn ２－ｘ P ２ O ７±δ This is a composite oxide represented by the formula (wherein part of Ca may be substituted with Sr and / or Ba and / or Mg, or all of Ca may be substituted with Sr and / or Ba; wherein part of the formula 0 < x < 2, and δ is a value determined to satisfy the charge neutrality condition). In this specification, the "charge neutrality condition" does not have to be completely neutral, and compositions with oxygen deficiencies or excesses within the range acceptable for the compound may be included.

[0011] Furthermore, the method for producing the composite oxide represented by the above general formula (1) according to the present invention is as follows: (a) a step of combining at least one selected from the group consisting of a Ca-containing compound, an Sr-containing compound, a Ba-containing compound, and an Mg-containing compound (except in the case of only an Mg-containing compound) with a Zn-containing compound and a P-containing compound to form a raw material mixture; (b) a step of obtaining a primary calcined product by calcining the raw material mixture obtained in step (a); (c) a step of obtaining a secondary calcined product by crushing and remixing the primary calcined product obtained in step (b) and then calcining it again; and (d) an optional step of obtaining an additional calcined product by performing step (c) at least once more. ｘ Zn ２－ｘ P ２ O ７±δ A method for producing a composite oxide represented by the formula (wherein part of Ca may be substituted with Sr and / or Ba and / or Mg, or all of Ca may be substituted with Sr and / or Ba, where 0 < x < 2 and δ is a value determined to satisfy the charge neutrality condition).

[0012] The composite oxide of the present invention can often exhibit negative thermal expansion characteristics in a lower temperature range and can preferably be used as a negative thermal expansion material with a higher thermal shrinkage coefficient. Furthermore, according to a preferred embodiment, by combining the composite oxide powder with a resin component to constitute a resin composition, the thermal expansion of the resin component can be effectively suppressed, making it suitable for use as a raw material for components of electronic products.

[0013] Figure 1 is a graph plotting the dimensional change ratio (ΔL / L) of the sintered composite oxide body obtained in each of Example 2 and Comparative Example 1, described later, against temperature change. Figure 2 is a graph plotting the dimensional change ratio (ΔL / L) of the compacted composite oxide body (unsintered) obtained in each of Examples 4 to 6, described later, against temperature change.

[0014] <Composite Oxide> The composite oxide according to the present invention is of general formula (1) Ca ｘ Zn ２－ｘ P ２ O ７±δ(In the formula, some of the Ca may be substituted with Sr and / or Ba and / or Mg, or all of the Ca may be substituted with Sr and / or Ba. In the formula, 0 < x < 2, and δ is a value determined to satisfy the charge neutrality condition.) Such composite oxides can often preferably exhibit negative thermal expansion characteristics in a lower temperature range and can be used as negative thermal expansion materials with a higher thermal contraction coefficient. In the above general formula (1) representing the composite oxide, it is even more preferable that x is about 0.1 < x < about 0.5 from the viewpoint of obtaining the effect of further reducing the thermal expansion coefficient.

[0015] In one embodiment, the general formula (1) Ca ｘ Zn ２－ｘ P ２ O ７±δ The composite oxide represented by may be a negative thermal expansion material having a negative coefficient of thermal expansion (negative thermal expansion coefficient) which has the property of decreasing in volume as the temperature rises. Such a negative thermal expansion material may have a temperature range in which the linear expansion coefficient (α: as defined below) is less than 0 ppm / K, preferably -10 ppm / K or less, more preferably -20 ppm / K or less, even more preferably -30 ppm / K or less, and even more preferably -40 ppm / K or less.

[0016] In this specification, the "coefficient of linear expansion (α)" is defined by the following formula (A): Coefficient of linear expansion (α) [unit ppm / K] = (1 / L) × (ΔL / ΔT) × 10 ６...Equation (A) In the equation, L refers to the length of the sample (μm), ΔL refers to the change in sample length (μm) within the specified temperature range, and ΔT refers to the temperature difference (K) within the specified temperature range. In this specification, the "dimensional change ratio," which is the ratio of the change in sample length within the specified temperature range, is defined by the following equation (B). Dimensional change ratio (dimensionless) = ΔL / L ...Equation (B) ΔL and L in the equation are as defined above. The coefficient of linear expansion (α) is expressed in the following relationship with the dimensional change ratio ΔL / L. Coefficient of linear expansion (α) [ppm / K] = {(ΔL / L) / ΔT} × 10 ６

[0017] In one embodiment, the composite oxide represented by general formula (1) may have a temperature range in which the dimensional change ratio (ΔL / L) is less than 0, preferably in any range within the temperature range of -200°C to 500°C, preferably in any range within the temperature range of 0°C to 200°C, and more preferably in a temperature range of room temperature or higher (for example, 0°C or higher, 10°C or higher, 20°C or higher, or 30°C or higher) up to 150°C or 140°C or lower. Preferably, it is -2 × 10 －３ It may have a temperature range of the following, more preferably -3 × 10 －３ It may have a temperature range of the following, and more preferably -4 × 10 －３ The temperature range may be as follows, and more preferably -6 × 10 －３ The following temperature range may be observed: In other embodiments, the composite oxide represented by general formula (1) has a dimensional change ratio (ΔL / L) of -8 × 10 in any range within the temperature range of -200°C to 500°C, preferably in any range within the temperature range of 0°C to 200°C, and more preferably in a temperature range of room temperature or higher (e.g., 0°C or higher, 10°C or higher, 20°C or higher, or 30°C or higher) up to 150°C or 140°C or lower. －３ It may have a temperature range of the following, or -10 × 10 －３ The following temperature range may be included.

[0018] The dimensional change ratio (ΔL / L: the ratio of length change due to linear expansion) in this specification may be measured in the state of a compacted molded body (unsintered) of a negative thermal expansion material (powder), or by sintering this compacted molded body. The dimensional change ratio can be measured by a thermomechanical analyzer (TMA), for example, by a Hitachi High-Tech TA7000. When calculating the coefficient of linear expansion (α) using the above formula (A), when substituting the values ​​for L to ΔL as described above, the sample length in units of mm displayed on the above device should be set to 10 ３ You can convert it to the unit μm by multiplying by two.

[0019] By mixing two or more negative thermal expansion materials, such as composite oxides, it is possible to create a material that exhibits gradual thermal shrinkage with two or more shrinkage temperature ranges. This suppresses the rapid shrinkage of the negative thermal expansion material. Therefore, for example, a resin composition containing a mixture of two or more such negative thermal expansion materials can reduce the difference in thermal expansion between the resin and the composite material in the shrinkage temperature range compared to a resin composition containing only one negative thermal expansion material.

[0020] In X-ray diffraction measurements at 140°C using Cu-Kα rays as the X-ray source for a composite oxide represented by general formula (1), the peak intensity of the (-6 0 2) plane appearing at diffraction angles 2θ = 29.3 to 29.55° is A. １ The (0 2 2) plane peak intensity A appears at diffraction angle 2θ = 29.6 to 29.7°. ２ Peak intensity ratio A １ / A ２ The peak intensity ratio A in this range is more preferably 0.14 or less, even more preferably 0.13 or less, even more preferably 0.12 or less, even more preferably 0.11 or less, even more preferably 0.10 or less, and most preferably 0.095 or less. １ / A ２The composite oxide represented by the general formula (1) often has a relatively large negative coefficient of thermal expansion in any temperature range included in the above-mentioned temperature range of -200°C to 500°C. For the calculation of the peak intensity ratio of X-ray diffraction analysis in this specification, as shown in the examples below, a powder X-ray diffractometer (for example, Rigaku's "MiniFlex2") is used to observe the peaks by scanning with Cu-Kα rays at room temperature under the conditions of a tube voltage of 30 kV, a tube current of 15 mA, a scanning speed of 5° / min, and a scanning angle of 2θ = 5° to 80°. Other than the above, the operating conditions for powder X-ray diffraction are as follows: ・Slit: DS-SS; 1.25 degrees, RS; 0.3 mm ・Monochromator graphite step: 0.02° ・Counting method: Constant counting method ・X-ray analysis software: PDXL2 Version 2.9.1.0 By operating under the above conditions using a powder X-ray diffractometer, the XRD peak intensity ratio (-60²) / (0²²) and the XRD peak intensity ratio (20⁻¹) / (0²²) are measured at 30°C, 50°C, and 140°C, respectively. Here, the peak intensity of "(20⁻¹)" refers to the peak intensity of the (20⁻¹) plane that appears between 30.0° and 30.2°. A preferred embodiment of the composite oxide represented by general formula (1) exhibits a considerably low peak intensity ratio (-60²) / (0²²) and, in many cases, has a relatively large negative thermal expansion coefficient in any temperature range included in the above-mentioned temperature range of -200°C to 500°C. Therefore, it can be suitably used as a negative thermal expansion material for precision equipment such as semiconductor devices that are actually driven, in the temperature range of 150°C or less in the heat cycle of such precision equipment.

[0021] The composite oxide represented by general formula (1) has a temperature range in which the coefficient of linear expansion (α) is less than 0 ppm / K, preferably in any range within the temperature range of -200°C to 500°C, preferably in any range within the temperature range of 0°C to 200°C, and more preferably in a temperature range of room temperature or higher (for example, 0°C or higher, 10°C or higher, 20°C or higher, or 30°C or higher) to 150°C or 140°C or lower, and in an X-ray diffraction measurement at 140°C using Cu-Kα rays as the X-ray source for the composite oxide represented by general formula (1), the (-6 0 2) plane peak intensity A appears at the diffraction angle 2θ = 29.3 to 29.55°. １ The (0 2 2) plane peak intensity A appears at diffraction angle 2θ = 29.6 to 29.7°. ２ Peak intensity ratio A １ / A ２ It is preferable that is 0.15 or less. Furthermore, the composite oxide represented by general formula (1) may have a temperature range in which the coefficient of linear expansion (α) is preferably -10 ppm / K or less, more preferably -20 ppm / K or less, even more preferably -30 ppm / K or less, and even more preferably -40 ppm / K or less, in an X-ray diffraction measurement at 140°C using Cu-Kα rays as the X-ray source for the composite oxide represented by general formula (1), and the (-6 0 2) plane peak intensity A that appears at the diffraction angle 2θ = 29.3 to 29.55°. １ The (0 2 2) plane peak intensity A appears at diffraction angle 2θ = 29.6 to 29.7°. ２ Peak intensity ratio A １ / A ２However, it is preferably 0.14 or less, more preferably 0.13 or less, even more preferably 0.12 or less, even more preferably 0.11 or less, even more preferably 0.10 or less, and most preferably 0.095 or less. Such composite oxides can preferably exhibit negative thermal expansion characteristics in a lower temperature range (a temperature range of 150°C or less in the heat cycle of precision equipment such as semiconductor devices that are actually driven) and can be used as negative thermal expansion materials with a higher thermal shrinkage rate.

[0022] The shape and form of the composite oxide are not particularly limited, but may be any known shape. These shapes may include, for example, powders / particles of various shapes such as approximately spherical, plate-like, flaky, whisker-like, rod-like, filament-like, or crushed forms; solid or hollow approximately spherical molded bodies; solid or hollow approximately ellipsoidal molded bodies; solid or hollow approximately rectangular parallelepiped molded bodies; solid or hollow approximately cubic molded bodies; solid or hollow approximately cylindrical molded bodies; solid or hollow approximately prismatic molded bodies; or combinations of these shapes. In addition to powders, the composite oxide may also be compacted molded bodies, and may take various shapes such as film materials and plate materials. While the particle shape of the composite oxide in powder form is not particularly limited, it is preferable that the composite oxide contains a large proportion of spherical particles, from the viewpoint of achieving uniform mixing and dispersion when mixed with positive thermal expansion materials such as silica, and from the viewpoint of suppressing wear on the raw material mixing container and reducing the inclusion of impurities. Furthermore, it is preferable to include a large number of spherical particles in the composite oxide, as this improves the fluidity of the resin composition and can suppress viscosity increases.

[0023] When the composite oxide takes the form of a powder, it is preferable that the powder contains a large number of spherical particles with a sphericity (perfect sphericity) of 0.7 to 1.0. The content of spherical particles in the composite oxide powder may be 75% or more, preferably 80% or more, based on the number of particles, from the viewpoint of achieving a uniform mixing and dispersion state when mixed with positive thermal expansion materials such as silica, suppressing wear of the raw material mixing container, and reducing the inclusion of impurities. Furthermore, this provides the advantage of improving the fluidity of the resin composition and suppressing viscosity increase. In this specification, the sphericity of the composite oxide powder can be measured as follows. A sample of the composite oxide powder is observed at a magnification of 2500x using a scanning electron microscope (SU3500, manufactured by Hitachi High-Technologies Corporation) and three SEM images are obtained. For each of the three obtained SEM images, a binarization process of particles and background is performed as image adjustment. Subsequently, image analysis is performed on each of the 100 particles in the image. Using the image processing software ImageJ, drawing is performed along the particles. After all drawing is complete, particle analysis is performed to obtain the average area and average circumference of each particle. Then, the sphericity of one SEM image is calculated using equation (1). The arithmetic mean of the sphericity obtained from the three images is taken as the sphericity (true sphericity). Sphericity of one particle = 4π × (average area of ​​one particle) / (average circumference of one particle)^2 ... (1)

[0024] When a complex oxide takes the form of a powder, the average particle size of this powder is considered to have good dispersibility in matrix materials such as resins, glass, and metals, as measured by the cumulative particle size D at 50% of the cumulative volume using laser diffraction scattering particle size distribution analysis. ５０ It is preferable that the particle size is 0.1 μm or more and 100 μm or less. Volume cumulative particle size D of the composite oxide powder ５０ More preferably, the particle size may be 0.3 μm to 50 μm, 0.5 μm to 40 μm, 0.7 μm to 30 μm, 1 μm to 20 μm, or 1.2 μm to 10 μm.

[0025] When a complex oxide takes the form of a powder, the BET specific surface area of ​​this powder is 0.1 m². ２ / g or more 10m ２It is preferable that the BET specific surface area is less than or equal to 0.1 m². Having a BET specific surface area within this range can improve the dispersibility of the composite oxide powder in matrix materials such as resins, glass, and metals. The BET specific surface area of ​​the composite oxide powder is more preferably 0.1 m². ２ / g or more 8m ２ It may be less than or equal to / g, and more preferably 0.1m ２ / g or more 5m ２ / g or less, 0.1m ２ / g or more 4m ２ / g or less, 0.1m ２ / g or more 3m ２ / g or less, 0.1m ２ / g or more 2m ２ / g or less, 0.1m ２ / g or more 1m ２ / g or less, or 0.3m ２ / g or more 1m ２ It may be less than or equal to / g.

[0026] The volume resistivity of the composite oxide is 1.0 × 10⁻⁶ at 25°C, making it suitable for applications requiring insulation. ９ It is preferable that the resistivity is Ω·cm or greater. The volume resistivity of the composite oxide is more preferably 5.0 × 10 at 25°C. ９ Ω・cm or more, 1.0×10 １０ Ω・cm or more, 5.0×10 １０ Ω・cm or more, 1.0×10 １１ Ω・cm or more, 5.0×10 １１ Ω·cm or greater, or 1.0 × 10⁻⁶ １２ It may be Ω·cm or greater. In this specification, when the composite oxide takes the form of a powder, the volume resistivity of this powder can be measured, for example, by compressing the composite oxide powder at a pressure of 63 MPa using the powder resistance measurement system "MCP-PD51" manufactured by Nitto Seiko Analytech Co., Ltd., and measuring it according to the four-terminal method. Samples that exceed the measurement limit of this device can be prepared as pellets by separately compressing them at a pressure of 63 MPa, and measured using the high-resistivity meter Hi-Resta UX / MCP-HT800 manufactured by Nitto Seiko Analytech Co., Ltd.

[0027] <Method for Producing Composite Oxide> The composite oxide represented by the general formula (1) is not particularly limited, but can usually be produced by a dry synthesis method or a liquid-phase synthesis method (hydrothermal reaction method) appropriately selected. Hereinafter, embodiments of a method for producing the composite oxide represented by the general formula (1) will be described.

[0028] The general formula (1) Ca ｘ Zn ２－ｘ P ２ O ７±δ (In the formula, a part of Ca may be substituted with Sr and / or Ba and / or Mg, or all of Ca may be substituted with Sr and / or Ba. In the formula, 0 < x < 2, and δ is a value determined to satisfy the charge neutrality condition.) The dry synthesis method for obtaining the composite oxide represented by is, for example, (i) at least one selected from the group consisting of a raw material compound containing Ca, a raw material compound containing Sr, a raw material compound containing Ba, and a raw material compound containing Mg (however, excluding the case of only the raw material compound containing Mg), and a raw material compound mixture containing a raw material compound containing Zn and a raw material compound containing P, (ii) obtaining a primary fired product by firing the raw material compound mixture, (iii) obtaining a secondary fired product by crushing and remixing the primary fired product and then firing it again, (iv) optionally, obtaining an additional fired product by additionally performing step (iii) at least once, (v) crushing the secondary fired product or the additional fired product, (vi) optionally, pulverizing the crushed secondary fired product or the additional fired product, (vii) optionally, sieving the pulverized secondary fired product or the additional fired product with or without washing with water and decantation, and (viii) optionally, drying the sieved secondary fired product or the additional fired product.

[0029] The raw material compound containing Ca, which is part of the raw material compound mixture, is not particularly limited, and any known Ca-containing compound can be used. Examples of the raw material compound containing Ca include calcium oxide (CaO), calcium hydroxide (Ca(OH) ２ )), calcium carbonate (CaCO３ ), calcium chloride (CaCl ２ ), calcium nitrate (Ca(NO ３ ), ２ ), calcium sulfate (CaSO ４ ), etc. Raw material compounds containing Ca may be used as a mixture of one or more kinds. Usually, calcium oxide (CaO) can be used. Other examples of raw material compounds containing Ca include calcium salts with phosphorus compounds such as phosphoric acid, condensed phosphoric acids (e.g., pyrophosphoric acid, etc.), and phosphorous acid. Further, the raw material compounds containing Ca may be calcium salts with organic acids such as acetic acid, citric acid, and oxalic acid.

[0030] The raw material compounds containing Sr, which are part of the raw material compound mixture, are not particularly limited, and any known Sr-containing compounds can be used. Examples of raw material compounds containing Sr include strontium oxide (SrO), strontium hydroxide (Sr(OH) ２ ), strontium carbonate (SrCO ３ ), strontium chloride (SrCl ２ ), strontium nitrate (Sr(NO ３ ), ２ ), strontium sulfate (SrSO ４ ), etc. Raw material compounds containing Sr may be used as a mixture of one or more kinds. Usually, strontium carbonate (SrCO ３ ), can be used. Other examples of raw material compounds containing Sr include strontium salts with phosphorus compounds such as phosphoric acid, condensed phosphoric acids (e.g., pyrophosphoric acid, etc.), and phosphorous acid. Further, the raw material compounds containing Sr may be strontium salts with organic acids such as acetic acid, citric acid, and oxalic acid.

[0031] The raw material compounds containing Ba, which are part of the raw material compound mixture, are not particularly limited, and any known Ba-containing compounds can be used. Examples of raw material compounds containing Ba include barium oxide (BaO), barium hydroxide (Ba(OH) ２ ), barium carbonate (BaCO ３ ), barium chloride (BaCl ２ ), barium nitrate (Ba(NO３ ) ２ ), barium sulfate (BaSO ４ Examples include the following. The raw material compound containing Ba may be used as one or a mixture of several types. Typically, barium carbonate (BaCO3) is used. ３ ) may be used. Other examples of raw material compounds containing Ba include barium salts with phosphorus compounds such as phosphoric acid, condensed phosphoric acid (e.g., pyrophosphate), and phosphorous acid. Alternatively, the raw material compound containing Ba may be a barium salt with organic acids such as acetic acid, citric acid, and oxalic acid.

[0032] The raw material compound containing Mg, which is part of the raw material compound mixture, is not particularly limited, and any known Mg-containing compound can be used. Examples of Mg-containing raw material compounds include magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)). ２ ), magnesium carbonate (MgCO3) ３ ), magnesium chloride (MgCl ２ ), magnesium nitrate (Mg(NO) ３ ) ２ ), magnesium sulfate (MgSO ４ Examples include the following. The raw material compound containing Mg may be used as one or a mixture of several types. Typically, magnesium oxide (MgO) can be used. The raw material compound containing Mg may also be a magnesium salt with an organic acid such as acetic acid, citric acid, or oxalic acid.

[0033] The raw material compound containing Zn, which is part of the raw material compound mixture, is not particularly limited, and any known Zn-containing compound can be used. An example of a Zn-containing raw material compound is ZnO. Furthermore, the raw material compound containing P, which is part of the raw material compound mixture, is not particularly limited, and any known P-containing compound can be used. An example of a P-containing raw material compound is phosphoric acid (H ３ PO ４ ), diammonium hydrogen phosphate ((NH ４ ) ２ HPO ４ ), ammonium dihydrogen phosphate (NH ４ H ２ PO ４), ammonium phosphate, pyrophosphate, polyphosphate, Zn ２ P ２ O ７ Mg ２ P ２ O ７ Examples include one or more of the following.

[0034] The mixing ratio of at least one raw material compound selected from the group consisting of a raw material compound containing Ca, a raw material compound containing Sr, a raw material compound containing Ba, and a raw material compound containing Mg (except in the case of only a raw material compound containing Mg), as well as one or more raw material compounds containing Zn and one or more raw material compounds containing P, can be appropriately selected and adjusted according to the desired composition of the composite oxide.

[0035] The calcination temperature at each calcination stage in the dry synthesis method is not particularly limited, but may be, for example, 200°C or higher, 250°C or higher, or 300°C or higher, and may be 1200°C or lower, 1000°C or lower, or 900°C or lower. The calcination temperature range at each calcination stage in the dry synthesis method may be, for example, 200°C or higher and 1200°C or lower, or 250°C or higher and 1000°C or lower, or 300°C or higher and 900°C or lower. From the viewpoint of reliably obtaining a composite oxide having the desired composition, it is preferable to set the calcination temperature higher as the process progresses to the subsequent calcination stage. The number of times the calcination stage is repeated is usually two or three times, but it may be repeated four or more times if necessary.

[0036] The optional grinding of the secondary or additionally fired material after crushing may be dry or wet grinding. Dry grinding can be performed, for example, using a jet mill with a collision plate or a jet mill that causes particles to collide with each other. Wet grinding can be performed, for example, by adding a small amount of dispersant to the crushed and fired material as needed, and while stirring, supplying screws such as small-diameter zirconia beads to a media-stirring bead mill.

[0037] Optional sieving performed on the crushed calcined material may involve, for example, a volume cumulative particle size D within the preferred range described above. ５０An appropriate sieve can be selected to obtain a composite oxide powder having the following properties. Washing with water and decantation, which may be performed in conjunction with sieving, are preferably repeated until the desired conductivity of the supernatant liquid (e.g., 20 μS / cm or less) is achieved. Drying, which is optionally performed on the sieved calcined product, may be carried out, for example, at 50°C to 200°C, preferably 80°C to 150°C, for 30 minutes to 10 hours, preferably 1 hour to 8 hours.

[0038] A wet synthesis method for obtaining a complex oxide may include, for example, (i) preparing a mixture of raw material compounds including at least one selected from the group consisting of a raw material compound containing Ca, a raw material compound containing Sr, a raw material compound containing Ba, and a raw material compound containing Mg (except in the case of only a raw material compound containing Mg), as well as a raw material compound containing Zn and a raw material compound containing P; (ii) obtaining a hydrothermally treated mixture by hydrothermally treating the raw material compound mixture; (iii) optionally separating the solid and liquid from the hydrothermally treated mixture and washing it; (iv) drying the hydrothermally treated mixture; and (v) calcining the dried mixture.

[0039] At least one of the raw material compounds selected from the group consisting of a raw material compound containing Ca, a raw material compound containing Sr, a raw material compound containing Ba, and a raw material compound containing Mg, which are part of the raw material compound mixture, is not particularly limited as long as it is a compound containing Ca, a compound containing Sr, a compound containing Ba, or a compound containing Mg. Furthermore, the raw material compounds containing Zn and P, which are part of the raw material compound mixture, are not particularly limited as long as they are a compound containing Zn or a compound containing P. The raw material compounds containing Zn and P may each be the element in its elemental form. Examples of raw material compounds containing Ca, Sr, Ba, Mg, Zn, or P that are suitably used in liquid-phase synthesis (hydrothermal reaction) include one or more of the following: chloride salts or hydrates of the element, oxychloride salts or hydrates, acetates or hydrates, oxyacetates or hydrates, sulfates or hydrates, nitrates or hydrates, carbonates or hydrates, ammonium carbonates or hydrates, sodium carbonates or hydrates, potassium carbonates or hydrates, polyacids or salts or hydrates, oxides or hydrates. Sulfuric acid may be added to the raw material compound mixture as a sulfur raw material if necessary. For example, an example of a P-containing compound used as a raw material is phosphoric acid (H ３ PO ４ ), diammonium hydrogen phosphate ((NH ４ ) ２ HPO ４ ), ammonium dihydrogen phosphate (NH ４ H ２ PO ４ Examples include one or more of the following: ammonium phosphate, pyrophosphate, polyphosphate, etc.

[0040] The hydrothermal treatment conditions for the raw material compound mixture in the liquid-phase synthesis method (hydrothermal reaction method) are not particularly limited, but for example, the reaction can be carried out continuously in a sealed container under pressure at a temperature of 100°C to 250°C, preferably 110°C to 230°C, for a period of time of, for example, 30 minutes to 100 hours, preferably 1 hour to 80 hours, 2 hours to 60 hours, or 3 hours to 40 hours.

[0041] In the liquid-phase synthesis method (hydrothermal reaction method), washing after solid-liquid separation may be performed, for example, by adding water to separate the solid-liquid again or by washing with water. This washing operation may be repeated multiple times. If sulfur (S) components are present in the system, washing can effectively remove them.

[0042] In the liquid-phase synthesis method (hydrothermal reaction method), the drying of the hydrothermally treated mixture may be carried out, for example, at a temperature of 60°C to 200°C, preferably 50°C to 150°C, for about 30 minutes to 40 hours, preferably about 1 hour to 30 hours. Furthermore, the calcination of the dried mixture is not particularly limited, but may be at a temperature of 250°C or higher, 300°C or higher, or 350°C or higher, or 1200°C or lower, 1000°C or lower, or 900°C or lower.

[0043] <Composite Materials> One or more of the composite oxides represented by general formula (1) according to the above embodiments can be combined with other materials to form composite materials. Examples of other materials that can form such composite materials include, but are not limited to, composite oxides other than those represented by general formula (1), and resin components. Embodiments in which one or more powders of any of the composite oxides represented by general formula (1) are combined with resin components to constitute a resin composition that is a composite material will be described further below.

[0044] In embodiments in which one or more composite oxides represented by general formula (1) are combined with composite oxides other than those represented by general formula (1) (hereinafter referred to as "other composite oxides" for simplification) to form a composite material, the mass percentage of the composite oxide represented by general formula (1) in the composite material is not particularly limited and may be greater than 0% by mass and less than 100% by mass, but it may usually constitute the main component (i.e., it may account for more than 50% by mass and less than 100% by mass).

[0045] In embodiments in which one or more composite oxides represented by general formula (1) are combined with other composite oxides to form a composite material, examples of other composite oxides include composite oxides represented by the following general formula (2), which consist of at least one element selected from the group consisting of Ca, Sr, and Ba, and other element A (excluding the composite oxide represented by general formula (1) above). Ca ｘ A ｙ O ｚ±δ (In this formula, some or all of Ca may be substituted with Sr and / or Ba.) ... (2) In the formula, A is a mixture of one or more other elements that constitute a composite oxide, which includes at least one element selected from the group consisting of Ca, Sr, and Ba, and the other elements, and δ is a value determined to satisfy the charge neutrality condition. x and y are not 0 (zero), but are not particularly limited as long as the sum of them balances the valence with O, i.e., the charge neutrality condition is satisfied. x:y (molar ratio) may be, for example, between 0.001:99.999 and 99.999:0.001, preferably between 0.01:99.99 and 99.99:0.01, and more preferably between 0.1:99.9 and 99.9:0.1. When there are multiple other elements A (i.e., in the above formula, A ｙ A1 ｙ１ A2 ｙ２ In the case of ..., the mole fraction of one of them in the total element A may be, for example, between 0.001 and 99.999.

[0046] The other element A constituting a composite oxide comprising at least one element selected from the group consisting of Ca, Sr, and Ba in the above general formula (2) and the other element A is not particularly limited as long as it is an element capable of forming an oxide (except for the elements defined in the above general formula (1)). In one embodiment, the other element A constituting a composite oxide comprising at least one element selected from the group consisting of Ca, Sr, and Ba and the other element A may be one or a mixture of two or more elements, excluding Ca and O with atomic numbers 3 and above. Also in one embodiment, the composite oxide comprising at least one element selected from the group consisting of Ca, Sr, and Ba and the other element A includes a mixture of two or more composite oxides.

[0047] In one embodiment, the other element A constituting a composite oxide comprising at least one element selected from the group consisting of Ca, Sr, and Ba of the general formula (2) above and the other element A may be one or more elements belonging to Group 1, Group 2, Group 3, Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, Group 11, Group 12, Group 13, Group 14, Group 15, and Group 16 (except for the definition of the general formula (1) above). In other embodiments, the other element A constituting a composite oxide comprising at least one element selected from the group consisting of Ca, Sr, and Ba of the general formula (2) above and the other element A may be one or more elements belonging to any one of the groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, and 16, or a combination of elements (one or more) belonging to each of two or more groups (except for the definition of the general formula (1) above). In further embodiments, the other element A constituting the composite oxide comprising at least one element selected from the group consisting of Ca, Sr, and Ba of the above general formula (2) and the other element A may include, for example, one or more elements selected from the group consisting of Li, B, Mg, Al, Si, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Pd, Ag, In, Sn, Sb, Hf, Ta, W, Ir, Pb, Bi, La, and Ce (except for the definition of the above general formula (1)). The other composite oxide may exhibit negative thermal expansion characteristics in a lower temperature range and may be used as a negative thermal expansion material with a higher thermal shrinkage coefficient by appropriately selecting the other element A. In additional embodiments, from the viewpoint of suppressing the phenomenon of constituent elements in the other composite oxide eluting in the form of ionic molecules in the solvent or resin, element A may include Al and / or Si.

[0048] <Resin Composition> One or more powders of the composite oxides represented by general formula (1) according to the above embodiments may be combined with resin components to form a composite material resin composition. The type and amount of resin used in the resin composition are not particularly limited and may be selected and adjusted as appropriate to obtain the target negative thermal expansion properties or other desired properties. The term "resin composition" as used herein is intended to include both a composition that partially contains a solvent such as water or an organic solvent used when mixing the components to prepare the resin composition, and a composition in which such a solvent has been removed under reduced pressure after the preparation of the resin composition.

[0049] Examples of resins, though not particularly limited, include epoxy resins; polyolefin resins such as polyethylene resin and polypropylene resin; polyvinyl resins such as polyvinyl chloride resin and polyvinyl butyral resin; phenolic resins such as polyphenylene sulfide resin and polystyrene resin such as ABS; polyacrylate resins; polyamide resins; polyimide resins; polyamide-imide resins; polyetherimide resins; silicone resins; polycarbonate resins; ester resins or unsaturated polyester resins such as polybutylene terephthalate (PBT resin) and polyethylene terephthalate (PET resin); fluororesins; liquid crystal polymers; polysulfones; polyethersulfones; aromatic polyether ketone resins such as polyetherether ketones; and mixtures of two or more of these. Among these resins, epoxy resins are preferred from the viewpoint of balancing various properties such as rapid curing, mechanical properties, and heat resistance.

[0050] The amount of resin that constitutes the resin composition is not particularly limited, but is usually 5% by mass or more and 95% by mass or less, preferably 10% by mass or more and 80% by mass or less, more preferably 15% by mass or more and 75% by mass or less, or 20% by mass or more and 70% by mass or less, relative to the total amount of the resin composition.

[0051] The resin composition may contain, in addition to the composite oxide powder and resin components, at least one of the following inorganic material powders: silica (silicon dioxide), silicates, titanium oxide, graphite, sapphire (aluminum oxide), magnesium oxide, calcium oxide, silicon nitride, boron nitride, aluminum nitride, various glass materials, concrete materials, and various ceramic materials. The inorganic material powder may be in a crushed form, a spherical form, or an aggregate such as fumed silica. The inorganic material powder is preferably spherical in order to reduce the viscosity of the resin composition. For example, if the inorganic material powder is silica, it may be crystalline or amorphous. The total amount of the composite oxide powder and the inorganic material powder (if present) in the resin composition is not particularly limited, but is usually 5% to 95% by mass, preferably 10% to 80% by mass, more preferably 15% to 75% by mass, or 20% to 70% by mass, relative to the total amount of the resin composition.

[0052] The resin composition may contain a curing agent in addition to the composite oxide powder and resin components. Any known curing agent may be used, such as acid anhydride compounds, phenolic compounds, amine / amide compounds, and active ester compounds. The amount of curing agent included in the resin composition is not particularly limited, but is usually 0.05% to 10% by mass, preferably 0.1% to 5% by mass or 0.5% to 3% by mass, relative to the total amount of the resin composition.

[0053] Examples of acid anhydride compounds that may be included in the resin composition as curing agents include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, polypropylene glycol maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride. Examples of phenolic compounds that may be included in the resin composition as curing agents include dicyclopentadienephenol addition resins, phenol aralkyl resins, naphthol aralkyl resins, triphenylol methane resins, tetraphenylolethane resins, naphthol novolac resins, naphthol-phenol co-condensed novolac resins, naphthol-cresol co-condensed novolac resins, biphenyl-modified phenolic resins, aminotriazine-modified phenolic resins, and modified products thereof.

[0054] Examples of amine / amide compounds that may be included in the resin composition as curing agents include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, polypropylene glycol diamine, diethylenetriamine, triethylenetetramine, and pentaethylenehexamine; aromatic polyamines such as metaxylylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and phenylenediamine; alicyclic polyamines such as 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, and norbornanediamine; and polyamide resins synthesized from dicyandiamide, a dimer of linolenic acid, and ethylenediamine. Examples of active ester compounds that may be included in the resin composition include compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. Preferred examples of active ester compounds include those obtained by the condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound (or its halide) with a hydroxy compound and / or a thiol compound. More preferred examples of active ester compounds include those obtained from a carboxylic acid compound or its halide with a phenol compound and / or a naphthol compound. Examples of carboxylic acid compounds constituting such active ester compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, etc., or their halides.Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, dihydroxydiphenyl ether, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, polyhydroxynaphthylene ether, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, and dicyclopentadiene-phenol addition resins.

[0055] The resin composition may contain, in addition to one or more powders of the composite oxide represented by general formula (1), powders of other negative thermal expansion materials, such as powders of negative thermal expansion materials that do not contain Ca, Sr, or Ba. The mass ratio of the powder of the composite oxide represented by general formula (1) to the powder of the negative thermal expansion material that does not contain Ca, Sr, or Ba (if present) in the resin composition may be, for example, between 99.999:0.001 and 0.001:99.999.

[0056] Examples of negative thermal expansion materials that do not contain Ca, Sr, or Ba and may be included in a resin composition include: General formula: Zr ｘ (WO ４ ) ｙ±δ１ (PO ４ ) ｚ±δ２ At least one oxide represented by the formula (wherein 1.7 ≤ x ≤ 2.3, 0.8 ≤ y ≤ 1.2, 1.7 ≤ z ≤ 2.3, and δ1 and δ2 are values ​​that are independently determined to satisfy the charge neutrality condition); General formula: Zr ２．００－ｂ M ｂ S Ｙ P Ｚ O １２．００±δAt least one oxide represented by the formula (wherein M is at least one selected from Ti, Ce, Sn, Mn, Hf, Ir, Pb, Pd, Cr, W, Mo, 0 ≤ b < 2.00, 0 < Y < 0.30, Z ≥ 2.00, and δ is a value determined to satisfy the charge neutrality condition); General formula: Zr ２．００－ｂ M ｂ S Ｙ P Ｚ O １２．００±δ At least one oxide represented by the formula (wherein M is at least one selected from Ti, Ce, Sn, Mn, Hf, Ir, Pb, Pd, Cr, W, Mo, 0 ≤ b < 2.00, 0.30 ≤ Y ≤ 1.00, Z > 2.00, and δ is a value determined to satisfy the charge neutrality condition).

[0057] Other additives that may be included in the resin composition include inorganic fillers and fibers other than negative thermal expansion materials, lubricants and release agents such as fatty acid amides, fatty acid esters, and metal salts of fatty acids, ultraviolet absorbers such as benzotriazole compounds, benzophenone compounds, and phenyl salicylate compounds, hindered amine stabilizers, phenolic and phosphorus antioxidants, tin-based heat stabilizers, various antistatic agents, lubricity enhancers such as polysiloxanes, various coloring pigments, silane coupling agents, titanium coupling agents, dyes, plasticizers such as waxes and silicone resins, oxides of metals other than Ca, Sr, or Ba, composite oxides of multiple metals other than Ca, Sr, or Ba, and mixtures of two or more of these. The amount of such other additives in the resin composition is not particularly limited, but from the viewpoint of maintaining the negative thermal expansion properties and other properties of the resin composition, it is usually 5% by mass or less, preferably 3% by mass or less, relative to the total amount of the resin composition.

[0058] The alpha dose of the negative thermal expansion material and resin composition was 0.0200 cph / cm². ２ The following is preferable: By having the alpha radiation dose of the negative thermal expansion material and resin composition within this range, malfunctions caused by current noise generated by alpha radiation can be suppressed when the negative thermal expansion material and resin composition are used as encapsulating materials for semiconductor devices. The alpha radiation dose of the negative thermal expansion material and resin composition is more preferably 0.0150 cph / cm². ２Further more preferably, 0.0100 cph / cm² ２ The following may apply: The alpha dose of the negative thermal expansion material and resin composition is 0.050 cph / cm². ２ It may also be less than 0.020 cph / cm². ２ It may also be less than 0.010 cph / cm². ２ The following is also acceptable.

[0059] In this specification, for measuring the alpha dose, a semiconductor-type trace alpha-ray energy distribution analyzer may be used, or a measurement method using a gas prosional counter type analyzer or an ionization type analyzer based on the international standard JEDEC STANDARD may be used. When using a semiconductor-type trace alpha-ray energy distribution analyzer, for example, the Hitachi "KS-1000" may be used. When using a semiconductor-type trace alpha-ray energy distribution analyzer, alcohol treatment may be performed as a pretreatment. As a more specific measurement method when measuring the alpha dose of a powder sample of a negative thermal expansion material using a semiconductor-type trace alpha-ray energy distribution analyzer, the following procedure may be adopted: (i) Place the sample to be measured (10 g) and ethyl alcohol (25 ml) into a 50 ml beaker and diffuse the beaker in an ultrasonic cleaner for about 1 minute. (ii) Transfer the entire amount of sample in the beaker to the sample stage so that the surface is uniform, and allow to air dry for about 2 hours. (iii) After natural drying, place the sample stage in a vacuum desiccator, start the vacuum pump, and perform vacuum drying for approximately 3 hours or more. (iv) The vacuum-dried sample stage will be used as the sample for trace alpha radiation measurement. (v) Set the sample stage in the chamber of the measuring device and perform measurement for 200 hours. The effective measurement area is 169 cm². ２ The sample size shall be (13 cm x 13 cm). When measuring the alpha dose of a resin composition, the resin composition can be placed directly on the sample stage. The alpha dose shall be the net count value obtained by subtracting the background from the actual measurement result obtained by the above procedure. The surface alpha dose measured in the range of 2.0 to 10 MeV using the above-mentioned Hitachi KS-1000 device may be used as the alpha dose here.

[0060] In measuring alpha dose according to the international standard JEDEC STANDARD, the measurement can be performed by the following procedure: (i) Use a gas flow type alpha dose measuring device. As the sample to be measured, spread powder on a sample base, for example, with a surface area of ​​900 cm². ２ A sample sheet formed into a sheet shape is used. Depending on the device, the sample sheet may be one that fills the maximum measurement area. The sample sheet is placed as a measurement sample in the alpha dose measuring device (gas prosional counter type measuring device or ionization type measuring device), and PR gas is purged into it. The PR gas used conforms to the international standard JEDEC STANDARD. That is, the PR gas used for measurement is a mixture of 90% argon and 10% methane that has been filled into a gas cylinder for more than three weeks, and is a decayed radon (Rn) gas. (ii) After the PR gas is flowed through the alpha dose measuring device in which the sample sheet is placed for 12 hours and left to stand, the alpha dose measurement is performed for 72 hours. (iii) The average alpha dose is measured in "cph / cm²". ２ The alpha radiation dose is calculated as follows: Anomalies (such as counts due to device vibration) are removed from the count for that hour. The following devices are used for the above measurement method: ・Alpha-ray counter: For example, "LACS-4000M" manufactured by Sumika Analysis Center Co., Ltd. ・"Gas flow type alpha-ray measuring device (MODEL-1950)" manufactured by Alpha Science Co., Ltd. ・"Gas Flow Proportional Counter Model 8600A-LB" manufactured by Ordela Co., Ltd. ・"UltraLo-1800" manufactured by XIA Co., Ltd. The alpha radiation dose using this method is measured over a measurement area of ​​1000 cm². ２ From 4000cm ２ This refers to the alpha dose value calculated from the values ​​counted over 72 to 100 hours.

[0061] <Powder mixture> One or more powders of the composite oxides represented by general formula (1) according to the above embodiments may be combined with silica-containing powder or other thermally conductive powders to form a powder mixture.

[0062] The silica-containing powder that can constitute the powder mixture is not particularly limited as long as it is a particulate material containing silica. The silica-containing powder may be silica. As silica, fused silica or crystalline silica may be used. The silica-containing powder may be, for example, a core-shell type silica powder in which a silica layer is formed around core particles of resin particles or metal particles, or a hollow silica powder.

[0063] Other thermally conductive powders besides silica-containing powders are not particularly limited and may be any known ones. Examples of other thermally conductive powders include: carbon compounds such as graphite and diamond; metal oxides such as aluminum oxide, magnesium oxide, beryllium oxide, titanium oxide, zirconium oxide, and zinc oxide (other than composite oxides represented by general formula (1)); metal nitrides such as boron nitride, aluminum nitride, and silicon nitride; metal carbides such as boron carbide, aluminum carbide, and silicon carbide; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; metal carbonates such as magnesium carbonate and calcium carbonate; organic polymer calcined products such as acrylonitrile-based polymer calcined products, furan resin calcined products, cresol resin calcined products, polyvinyl chloride calcined products, sugar calcined products, and charcoal calcined products; composite ferrites of ferrite and Zn ferrite; Fe-Al-Si ternary alloys; metal powders, or mixtures thereof.

[0064] The particle shape of silica-containing powder or other thermally conductive powder is preferably substantially spherical from the viewpoint of fluidity when mixed with a matrix material such as resin. The cumulative volume particle size D at 50% cumulative volume, as measured by laser diffraction scattering particle size distribution analysis of silica-containing powder or other thermally conductive powder. ５０ From the same viewpoint as above, the particle size may be, for example, 0.5 μm or more and 10 μm or less, and preferably 2 μm or more and 7 μm or less.

[0065] The mass ratio of the composite oxide powder represented by general formula (1) to the silica-containing powder or other thermally conductive powder in the powder mixture may be, for example, between 1:99 and 100:0, or between 20:80 and 100:0, preferably between 30:70 and 95:5, more preferably between 40:60 and 90:10, and even more preferably between 50:50 and 80:20 or between 60:40 and 80:20.

[0066] In one embodiment, a powder mixture may be made by mixing powders of two or more negative thermal expansion materials, including a composite oxide represented by general formula (1), and further including silica-containing powder or other thermally conductive powder. In a further embodiment, a powder mixture can be made that includes powder of a composite oxide represented by general formula (1) and another negative thermal expansion material, wherein the other negative thermal expansion material has a temperature range in which its linear expansion coefficient (α) is less than 0 ppm / K in a temperature range of at least 0°C to 140°C. In a modified embodiment, a mixed material can be made by mixing two or more negative thermal expansion materials, including a composite oxide represented by general formula (1), and having a temperature range in which its linear expansion coefficient (α) is less than 0 ppm / K in a temperature range of at least 0°C to 140°C. Furthermore, in a related modified embodiment, a mixed material can be constructed by mixing two or more negative thermal expansion materials, each having a temperature range in which the linear expansion coefficient (α) is less than 0 ppm / K in a temperature range of at least 0°C to 140°C, and each having a temperature range in which the linear expansion coefficient (α) is less than 0 ppm / K in a temperature range of at least 0°C to 140°C, and the mixed material is a powder mixture obtained by mixing powders of two or more negative thermal expansion materials.

[0067] <Method for Manufacturing Electronic Components> For example, an electronic component can be manufactured by (1) applying a resin composition, which is a composite material containing one or more types of powders of the composite oxide represented by general formula (1) according to the above embodiments and a resin component, to a first member; (2) applying a second member to the resin composition simultaneously with or after the application of the resin composition to the first member to obtain a component assembly in which the resin composition is sealed between the first and second members; and (3) sealing the space between the first and second members with the resin composition by pressing the component assembly under heat simultaneously with or after obtaining the component assembly. In the manufacture of such an electronic component, a sealing material containing a resin composition, which is a composite material containing the powder of the composite oxide and a resin component, can be applied for sealing the electronic component. Furthermore, in the manufacture of such an electronic component, a sealing material containing a resin composition, which is a composite material containing the powder of the composite oxide and a resin component, can be applied as an underfill for sealing electronic components. In other words, the present application provides an electronic component encapsulant comprising (or formed from) a resin composition which is a composite material comprising a composite oxide powder and a resin component; and also provides an electronic component encapsulant underfill comprising (or formed from) a resin composition which is a composite material comprising a composite oxide powder and a resin component. The electronic component encapsulant underfill can be rephrased as an electronic component underfill encapsulant.

[0068] As the resin composition, which is a composite material applied to the first member, either a composite oxide powder represented by the general formula (1) above or a resin composition containing a resin component can be appropriately selected. The first member and the second member are not particularly limited, as long as the resin composition can be applied to their surfaces and they can withstand pressure bonding under heat. The materials constituting the first member and the second member may be the same or different. Specific examples of the first member and the second member include silicon wafers, metal plates, glass plates, heat-resistant resin plates, and electronic components such as semiconductor chips. For example, it is conceivable that one of the first member and the second member is a silicon wafer on which electrodes are mounted as a circuit board, and the other is a semiconductor chip on which electrodes are mounted.

[0069] In a preferred embodiment, a resin composition, which is a composite material containing the powder of the composite oxide represented by the general formula (1) and a resin component, is applied as an underfill encapsulant to a circuit board, which is a silicon wafer, a first component. A semiconductor chip, which is a second component, is placed on top of the resin composition, which is the underfill encapsulant. Then, by pressing under heating, the resin composition is cured and the electrodes formed on the semiconductor chip and the electrodes formed on the circuit board are connected simultaneously, thereby sealing the connection between the semiconductor chip and the circuit board with the resin composition, and thus an electronic component (semiconductor device) can be manufactured. The heating temperature for pressing under heating is not particularly limited as long as the molten state of the resin constituting the resin composition is maintained. The pressure applied for pressing under heating is not particularly limited as long as the connection between the semiconductor chip and the circuit board can be reliably achieved. Such a thermocompression bonding method is called the NCP (Non-Conductive Paste) method. The NCP method offers advantages such as shortening the process and curing time, which in turn can provide a low-cost and low-energy pre-filled flip-chip bonding process. Furthermore, this thermocompression bonding method can suppress the generation of unfilled areas (voids) in the sealant and achieve a sufficient filling rate, even when the sphericity (perfect sphereness) of the composite oxide powder contained in the resin composition is not high.

[0070] In another preferred embodiment, a film-like semiconductor encapsulant, pre-formed from a resin composition which is a composite material containing the composite oxide powder represented by the general formula (1) and a resin component, is laminated onto a semiconductor chip, which is a first component. Then, the film-like semiconductor encapsulant is pressed onto a circuit board, which is a second component, under heat to connect the electrodes formed on the semiconductor chip and the electrodes formed on the circuit board. Subsequently, the resin composition is heat-cured to manufacture an electronic component (semiconductor device) in which the semiconductor chip is mounted on a circuit board. Similar to the embodiments described above, the heating temperature for pressing under heat is not particularly limited as long as the molten state of the resin constituting the resin composition is maintained. The pressure applied for pressing under heat is not particularly limited as long as a reliable connection between the semiconductor chip and the circuit board can be achieved. Such a thermocompression bonding method is called the NCF (Non-Conductive Film) method. Advantageous of the NCF method is that even when the gap between the semiconductor chip and the substrate is narrow, good bonding performance can be achieved through reliable sealing with suppressed void generation. Furthermore, this thermocompression bonding method, like the NCP method, can suppress the generation of unfilled areas (voids) in the encapsulant and achieve a sufficient filling rate, even when the sphericity (perfect sphereness) of the composite oxide powder contained in the resin composition is not high.

[0071] In other preferred embodiments, instead of the NCP method or NCF method described above, electronic components (semiconductor devices) can be manufactured by the ACP (Anitropic Conductive Paste) method or ACF (Anitropic Conductive Film) method, which involves mixing predetermined conductive particles with a resin composition that is a composite material containing the powder of the composite oxide represented by the general formula (1) and a resin component to form an anisotropic conductive adhesive, and then performing a similar process. The conductive particles are not particularly limited, but examples include metal particles (e.g., nickel or composite materials of nickel coated with gold), resin particles such as acrylic resin that are metal-plated (e.g., gold-plated), or particles having an insulating film on which they are destroyed or melted by heat or pressure. The average size of the conductive particles may be, for example, 1 μm to 50 μm. This thermocompression bonding method, like the NCP or NCF methods, can suppress the generation of unfilled areas (voids) in the encapsulant and achieve a sufficient filling rate, even when the sphericity (perfect sphereness) of the composite oxide powder contained in the resin composition is not high.

[0072] The present invention will be described in more detail below with reference to examples. These examples should be understood as merely illustrative and not as limiting the present invention in any way.

[0073] Preparation of a composite oxide containing P, Zn, and Ca Example 1 By dry synthesis, Zn １．９ Ca ０．１ P ２ O ７ A composite oxide ceramic sintered particle represented by was prepared. Specifically, 23.309 g of raw materials ZnO, 0.867 g of CaO, and (NH were weighed in stoichiometric ratios.) ４ ) H ２ PO ４34.613 g was mixed in a mortar in the open air. Next, the mixed powder was calcined in an electric furnace at 250°C in the open air for 5 hours. Then, the resulting calcined material was manually crushed in a mortar in the open air and remixed, and then calcined again in an electric furnace at 350°C in the open air for 10 hours. Next, the resulting calcined material was crushed in a Force Mill for about 30 seconds and remixed, and then calcined again in an electric furnace at 900°C in the open air for 10 hours. After crushing this calcined material in a Force Mill for about 30 seconds, it was further placed in a plastic container with 1.0 mm diameter zirconia beads and pure water, and the plastic container was set in a rocking shaker manufactured by Seiwa Giken Co., Ltd., and the rocking shaker was used to perform a grinding operation for 1 hour. Then, solid-liquid separation was performed by sieving using a 300 μm mesh sieve to obtain the desired average particle size. Subsequently, this powder was mixed with pure water and allowed to stand until it settled naturally, followed by washing with decantation. The washing was repeated until the conductivity of the supernatant (measured according to JIS K0130:2008) was ≤20 μS / cm, and then the same solid-liquid separation was performed again. The particles after solid-liquid separation were dried at approximately 110°C for 3 hours, and then crushed using a force mill for approximately 30 seconds to obtain composite oxide particles (powder). The X-ray diffraction pattern of the powder was evaluated using powder X-ray diffraction (XRD) (measurement temperature 295 K, characteristic X-rays of CuKα: wavelength λ = 0.15418 nm) and synchrotron radiation temperature-dependent X-ray diffraction (wavelength λ = 0.06521 nm), and Zn １．９ Ca ０．１ P ２ O ７ The formation of the crystalline structure was confirmed. The average particle size D of the obtained composite oxide particles (powder) ５０ (Volume cumulative particle size D at 50% cumulative volume measured by laser diffraction scattering particle size distribution method) ５０ The size (and so on) was 4.48 μm.

[0074] Example 2 Raw materials ZnO, CaO and (NH ４ ) H ２ PO ４ Except for changing the amount used to obtain the desired composition, the same method as in Example 1, Zn １．８ Ca ０．２ P２ O ７ Ceramic sintered particles of a composite oxide represented by were prepared. The average particle size D of the obtained composite oxide particles was ５０ It was 3.77 μm.

[0075] Example 3 Raw materials ZnO, CaO and (NH ４ ) H ２ PO ４ Except for changing the amount used to obtain the desired composition, the same method as in Example 1, Zn １．５ Ca ０．５ P ２ O ７ Ceramic sintered particles of a composite oxide represented by were prepared. The average particle size D of the obtained composite oxide particles was ５０ It was 1.54 μm.

[0076] Example 4 - Preparation of Ca-free composite oxide ceramic sintered particle example 1 By dry synthesis, Zn was synthesized as follows: １．６ Mg ０．４ P ２ O ７ A ceramic powder, which is a compound powder of a negative thermal expansion material represented by , was prepared. Specifically, MgO, ZnO, and ammonium dihydrogen phosphate (NH₄) were weighed in stoichiometric ratios of Zn, Mg, and P. ４ H ２ PO ４The mixture was stirred and mixed in a bag for 60 seconds until no agglomeration occurred. Next, the mixed powder was pressed into pellets and subjected to primary firing in an electric furnace at 250°C in air for 5 hours. Then, the resulting fired product was crushed in a mortar and remixed, and further subjected to secondary firing in an electric furnace at 350°C in air for 5 hours. Next, the resulting fired product was crushed in a Force Mill pulverizer for about 30 seconds and remixed, and further fired in an electric furnace at 900°C in air for 10 hours. This fired product was crushed in a Force Mill pulverizer for about 30 seconds. After that, it was placed in a plastic container along with 1.0 mm diameter zirconia beads and pure water, the plastic container was set in a rocking shaker manufactured by Seiwa Giken Co., Ltd., and the crushing operation was continued for another hour using the rocking shaker. Next, the zirconia beads were separated using a mesh, then solid-liquid separation was performed using a small centrifuge (Eppendorf Hi-Mac Technologies Co., Ltd.: CT6E), and the solid content was dried at 110°C using a dryer to obtain the raw material powder. The X-ray diffraction patterns of the compound powder were evaluated using powder X-ray diffraction (XRD) (measurement temperature 295 K, characteristic X-rays of CuKα: wavelength λ = 0.15418 nm) and synchrotron radiation temperature-dependent X-ray diffraction (wavelength λ = 0.06521 nm), and Zn １．６ Mg ０．４ P ２ O ７ The formation of the crystal structure was confirmed. Preparation of mixed powder of Ca-free composite oxide and Ca-containing composite oxide A mixed powder was prepared by weighing the ceramic sintered particles (powder) of the Ca-containing composite oxide obtained in Example 2 and the ceramic sintered particles (powder) of the Ca-free composite oxide obtained in Preparation Example 1 so that the volume ratio of the powder from Example 2 to the powder from Preparation Example 1 was 1:1 and mixing them.

[0077] Example 5 A mixed powder was prepared by weighing and mixing the Ca-containing composite oxide ceramic sintered particles (powder) obtained in Example 2 and the Ca-free composite oxide ceramic sintered particles (powder) obtained in Preparation Example 1 so that the volume ratio of the powder from Example 2 to the powder from Preparation Example 1 was 1:3.

[0078] Example 6 A mixed powder was prepared by weighing and mixing the Ca-containing composite oxide ceramic sintered particles (powder) obtained in Example 2 and the Ca-free composite oxide ceramic sintered particles (powder) obtained in Preparation Example 1 so that the volume ratio of the powder from Example 2 to the powder from Preparation Example 1 was 3:1.

[0079] Preparation of a composite oxide containing P, Zn, Ca, and Mg Example 7 By dry synthesis, Zn １．７ Ca ０．１ Mg ０．２ P ２ O ７ A composite oxide ceramic sintered particle was prepared. Specifically, 20.752 g of raw materials ZnO, 1.545 g of CaO, 1.209 g of MgO and (NH₄) were weighed in stoichiometric ratios. ４ ) H ２ PO ４ 34.613 g was mixed in a mortar in the open air. Next, the mixed powder was calcined in an electric furnace at 500°C in the open air for 5 hours. Then, the resulting calcined material was manually crushed in a mortar in the open air and remixed, and then calcined again in an electric furnace at 900°C in the open air for 10 hours. This calcined material was crushed for about 30 seconds using a Force Mill pulverizer, and then placed in a plastic container with 1.0 mm diameter zirconia beads and pure water. The plastic container was then placed in a rocking shaker manufactured by Seiwa Giken Co., Ltd., and the material was crushed using the rocking shaker for 1 hour. Next, solid-liquid separation was performed by sieving with suction filtration using a sieve with a mesh size of 300 μm to obtain the desired average particle size. After that, this powder was mixed with pure water, allowed to stand until natural sedimentation occurred, and then washed with decantation. The supernatant was repeatedly washed until its conductivity (measured according to JIS K0130:2008) was ≤20 μS / cm, and then the same solid-liquid separation was repeated. The particles after solid-liquid separation were dried at approximately 110°C for 3 hours, and then crushed using a Force Mill grinder for approximately 30 seconds to obtain composite oxide particles (powder). The X-ray diffraction pattern of the powder was evaluated using powder X-ray diffraction (XRD) (measurement temperature 295 K, characteristic X-rays of CuKα: wavelength λ = 0.15418 nm) and synchrotron radiation temperature-dependent X-ray diffraction (wavelength λ = 0.06521 nm), and Zn１．７ Ca ０．１ Mg ０．２ P ２ O ７ The formation of the crystalline structure was confirmed. The average particle size D50 (volume cumulative particle size D50 at a cumulative volume of 50% by laser diffraction scattering particle size distribution measurement method, the same applies hereafter) of the obtained composite oxide particles (powder) was 4.31 μm.

[0080] Example 8 Raw materials ZnO, CaO, MgO and (NH ４ ) H ２ PO ４ Except for changing the amount used to obtain the desired composition, the same method as in Example 7, １．７ Ca ０．２ Mg ０．１ P ２ O ７ Ceramic sintered particles of a composite oxide represented by were prepared. The average particle size D of the obtained composite oxide particles was ５０ It was 4.56 μm.

[0081] Preparation of a composite oxide containing P, Zn, Sr, Ba, and Mg: Example 9 Starting materials: ZnO, SrCO ３ BaCO ３ , MgO and (NH ４ ) H ２ PO ４ Except for using and changing the amounts of these to obtain the desired composition, the same method as in Example 7 was used, with the exception of Zn. １．７ Mg ０．１ Sr ０．１ Ba ０．１ P ２ O ７ Ceramic sintered particles of a composite oxide represented by were prepared. The average particle size D of the obtained composite oxide particles was ５０ The size was 4.40 μm.

[0082] Preparation Example 10 of a composite oxide containing P, Zn, Ca, Sr, Ba, and Mg: Raw materials ZnO, CaO, SrCO ３ BaCO ３ , MgO and (NH ４ ) H ２ PO ４Except for using and changing the amounts of these to obtain the desired composition, the same method as in Example 7 was used, with the exception of Zn. １．６ Mg ０．１ Ca ０．１ Sr ０．１ Ba ０．１ P ２ O ７ Ceramic sintered particles of a composite oxide represented by were prepared. The average particle size D of the obtained composite oxide particles was ５０ It was 4.12 μm.

[0083] Comparative Example 1: Raw materials ZnO and (NH ４ ) H ２ PO ４ Except for changing the amount used to obtain the desired composition, the same method as in Example 1, Zn ２ P ２ O ７ Ceramic sintered particles of a composite oxide represented by [formula] were prepared. CaO was not used as a raw material. The average particle size D of the obtained composite oxide particles was [formula]. ５０ It was 1.53 μm.

[0084] Compositional Analysis The composition (atomic ratio) of the samples obtained in each example and comparative example was analyzed using ICP-OES (Inductivity Coupled Plasma Optical Emission Spectrometry). The Agilient 5110 (manufactured by Agilient Technologies) was used as the ICP-OES instrument.

[0085] Measurement methods for various physical properties: Volume cumulative particle size D by laser diffraction scattering particle size distribution measurement method １０ , D ５０ and D ９０ Measurement: The samples obtained in each example and comparative example were placed in pure water and dispersed by ultrasonic irradiation (40W, 3 minutes). Then, using a particle size distribution analyzer (Microtrac (product name) MT-3300EXII (model number) manufactured by Microtrac-Bell Co., Ltd.), the cumulative volume particle size D at 10% cumulative volume was measured using the laser diffraction scattering particle size distribution method. １０ Volume cumulative particle size D at a cumulative volume of 50% ５０ , and volume cumulative particle size D at 90% of cumulative volume９０ We measured it.

[0086] XRD Peak Observation and Intensity Ratio Measurement: For the samples obtained in each example and comparative example, peaks were observed by scanning with a powder X-ray diffractometer (Rigaku "MiniFlex2") at room temperature using Cu-Kα rays under the conditions of tube voltage 30kV, tube current 15mA, scanning speed 5° / min, and scanning angle 2θ = 5° to 80°. Other than the above, the operating conditions for powder X-ray diffraction were as follows: ・Slit: DS-SS; 1.25 degrees, RS; 0.3 mm ・Monochromator graphite step: 0.02° ・Counting method: Constant counting method ・X-ray analysis software: PDXL2 Version 2.9.1.0 Using a powder X-ray diffractometer under the above conditions, the XRD intensity ratios (-60²) / (0²²) and (20-1) / (0²²) were measured at 30°C, 50°C, and 140°C, respectively. Here, the peak intensity of "(-6 0 2)" refers to the peak intensity of the (-6 0 2) plane that appears at diffraction angles 2θ = 29.3 to 29.55°, the peak intensity of "(0 2 2)" refers to the peak intensity of the (0 2 2) plane that appears at diffraction angles 2θ = 29.6 to 29.7°, and the peak intensity of "(2 0 - 1)" refers to the peak intensity of the (2 0 - 1) plane that appears at 30.0 to 30.2°.

[0087] ・Method for measuring the dimensional change ratio (ΔL / L) by TMA 1 g of a composite oxide sample, which is a negative thermal expansion material (powder) from any of Examples 1-3, Examples 7-10, or Comparative Example 1, along with 0.1 g of a 10% granulated binder (PV-217, manufactured by AS ONE) solution and 0.2 g of ethanol, were mixed in an agate mortar. After placing the mixture into a tablet molding die, the tablets were formed by pressurizing to obtain a molded body measuring 10 mm (diameter) x 5 mm (height). The molded body was dried at 110°C for 1 hour, and then fired at the same temperature as the tertiary firing temperature to create a sintered body. The dimensional change ratio of the sintered body was then measured. In addition, a mixed powder of any of the composite oxides from Examples 4-6 was placed into a tablet molding die, pressed into a tablet, and dried at 110°C for 1 hour to create a compacted powder molded body (unsintered) measuring 10 mm (diameter) x 5 mm (height). Subsequently, the dimensional change ratio of the compacted molded body (unsintered) was measured. The measurement conditions for the dimensional change ratio using TMA were as follows: • Apparatus: TA7000 (Hitachi High-Tech Thermomechanical Analyzer TMA7000 series) • One cycle only: The material was heated from 30°C to 250°C in an atmospheric environment at a heating rate of 6°C / min.

[0088] Powder properties of composite oxide particles of Examples 1-10 and Comparative Example 1. Volume cumulative particle size D was measured for the composite oxide particles (powder) of Examples 1-3, Examples 7-10, and Comparative Example 1. １０ , D ５０ , D ９０ The value and (D ９０ -D １０ ) / D ５０Table 1 below shows the calculated values, the XRD peak intensity ratios (-6 0 2) / (0 2 2) and (2 0 -1) / (0 2 2) at 30°C, 50°C, and 140°C, respectively, as well as the dimensional change ratio (ΔL / L) at 30°C, 50°C, and 140°C, along with the raw materials used and the composition of the composite oxide. Table 2 below also shows the dimensional change ratios (ΔL / L) at 30°C, 50°C, and 140°C measured for the mixed powders of Examples 4 to 6, along with the raw materials used and the composition of the mixed powder. From the results shown in Table 1, it can be seen that, very preferably, the composite oxide particles containing Ca or its substitute elements (Mg, Sr, Ba) of Examples 1 to 3 and Examples 7 to 10 obtained sufficient negative thermal expansion characteristics at 140°C due to a change in crystal structure, and also obtained a lower dimensional change ratio (higher negative thermal expansion characteristics) compared to Comparative Example 1.

[0089]

[0090]

[0091] The novel composite oxide according to the present invention exhibits negative thermal expansion characteristics in a lower temperature range, and is preferably used as a negative thermal expansion material with a higher thermal shrinkage coefficient. This is advantageous because it can further suppress the possibility of misalignment, interfacial delamination, and wire breakage caused by differences in thermal expansion coefficients between materials. Therefore, it is possible to suppress product defects during the manufacture of highly advanced electronic and optical equipment, fuel cells, and sensors, as well as damage and deterioration during repeated use. Furthermore, it is possible to reduce waste during manufacturing and use, and to reduce energy costs. In these respects, the composite oxide of the present invention enables the sustainable management and efficient use of natural resources and promotes decarbonization (carbon neutrality) in the manufacture and use of composite oxides and electronic equipment.

Claims

1. General formula (1) Ca ｘ Zn ２－ｘ P ２ O ７±δ A composite oxide represented by the formula (wherein part of Ca may be substituted with Sr and / or Ba and / or Mg, or all of Ca may be substituted with Sr and / or Ba; wherein the formula 0 < x < 2, and δ is a value determined to satisfy the charge neutrality condition).

2. The composite oxide according to claim 1, wherein the composite oxide is a negative thermal expansion material having a temperature range in which the coefficient of linear expansion (α) is less than 0 ppm / K in a temperature range of at least 0°C to 140°C.

3. The composite oxide according to claim 1, wherein the composite oxide is a negative thermal expansion material having a temperature range in which the dimensional change ratio (ΔL / L) is less than 0 in at least the temperature range of 0°C to 140°C.

4. The composite oxide has a temperature range of at least 30°C to 140°C of -4 × 10 －３ The composite oxide according to claim 3, which is a negative thermal expansion material having the following dimensional change ratio (ΔL / L).

5. In the X-ray diffraction measurement at 140 °C using Cu-Kα line as the X-ray source, the peak intensity A of the (-6 0 2) plane appearing at a diffraction angle 2θ = 29.3 to 29.55 ° １ and the peak intensity A of the (0 2 2) plane appearing at a diffraction angle 2θ = 29.6 to 29.7 ° ２ and the peak intensity ratio A １ / A ２ is 0.15 or less. The composite oxide according to claim 1.

6. The composite oxide is a negative thermal expansion material having a temperature range in which the coefficient of linear expansion (α) is less than 0 ppm / K in at least the temperature range of 0°C to 140°C, and in X-ray diffraction measurements at 140°C using Cu-Kα rays as the X-ray source, the (-602) plane peak intensity A appears at the diffraction angle 2θ = 29.3 to 29.55°. １ The (0 2 2) plane peak intensity A appears at diffraction angle 2θ = 29.6 to 29.7°. ２ Peak intensity ratio A １ / A ２ The composite oxide according to claim 1, wherein is 0.15 or less.

7. A composite material comprising the composite oxide described in claim 1.

8. The composite material according to claim 7, comprising a composite oxide other than the composite oxide described in claim 1, in addition to the composite oxide described in claim 1.

9. The composite material according to claim 7, wherein the composite material is a resin composition comprising the composite oxide powder and resin component described in claim 1.

10. The composite material according to claim 9, wherein the resin composition further comprises a curing agent.

11. The alpha dose of the resin composition is 0.0200 cph / cm². ２ The composite material according to claim 9, which is as follows:

12. A powder mixture comprising the powder of the composite oxide described in claim 1, and a silica-containing powder or other thermally conductive powder.

13. Encapsulating material for electronic components comprising the composite material described in claim 9.

14. An underfill for encapsulating electronic components, comprising the composite material described in claim 9.

15. A powder mixture comprising the powder of the composite oxide described in claim 1 and another negative thermal expansion material, wherein the other negative thermal expansion material has a temperature range in which its linear expansion coefficient (α) is less than 0 ppm / K in a temperature range of at least 0°C to 140°C.

16. A mixed material obtained by mixing two or more negative thermal expansion materials, having a temperature range in which the linear expansion coefficient (α) is less than 0 ppm / K in a temperature range of at least 0°C to 140°C, and the general formula (1) Ca ｘ Zn ２－ｘ P ２ O ７±δ A mixed material containing a composite oxide represented by the formula (wherein part of Ca may be substituted with Sr and / or Ba and / or Mg, or all of Ca may be substituted with Sr and / or Ba, where 0 < x < 2 and δ is a value determined to satisfy the charge neutrality condition).

17. A mixed material according to claim 16, wherein the mixed material is a powder mixture obtained by mixing powders of two or more negative thermal expansion materials, each having a temperature range in which the coefficient of linear expansion (α) is less than 0 ppm / K in a temperature range of at least 0°C to 140°C.

18. A method for manufacturing an electronic component, comprising: applying the composite material described in claim 9 to a first member; applying a second member to the composite material simultaneously with or after the application of the composite material to the first member to obtain a component assembly in which the composite material is sealed between the first and second members; and sealing the space between the first and second members with the composite material simultaneously with or after obtaining the component assembly by pressing the component assembly under heating.

19. A method for producing a raw material mixture comprising: (a) a step of combining at least one compound selected from the group consisting of Ca-containing compounds, Sr-containing compounds, Ba-containing compounds, and Mg-containing compounds (except in the case of only Mg-containing compounds) with a Zn-containing compound and a P-containing compound to form a raw material mixture; (b) a step of obtaining a primary calcined product by calcining the raw material mixture obtained in step (a); (c) a step of obtaining a secondary calcined product by crushing and remixing the primary calcined product obtained in step (b) and then calcining it again; and (d) an optional step of obtaining an additional calcined product by performing step (c) at least once more. ｘ Zn ２－ｘ P ２ O ７±δ A method for producing a composite oxide represented by the formula (wherein part of Ca may be substituted with Sr and / or Ba and / or Mg, or all of Ca may be substituted with Sr and / or Ba, where 0 < x < 2 and δ is a value determined to satisfy the charge neutrality condition).

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