Powder, method for producing negative thermal expansion material, method for producing composite material, and composite material

Abstract

Provided is a powder comprising a negative thermal expansion material including a compound represented by general formula (1): Znx1Tx2Py1Ay2Oz (T includes at least one element selected from among Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, and Ho, A includes at least one element selected from among Li, Ca, Sr, Ba, Al, Si, V, Ge, Sn, La, Ce, Y, Pr, Nd, and Sm, 0 ≤ x2 < 2, 0 ≤ y2 ≤ 2, 1.7 ≤ x1 + x2 ≤ 2.3, 1.7 ≤ y1 + y2 ≤ 2.3, and 6 ≤ z ≤ 8). The powder has a 90% volume-frequency particle diameter (D90) of 50 μm or less.

Description

Method for producing powders, materials with negative thermal expansion, method for producing composite materials, and composite materials Cross-reference of related applications

[0001] This application is based on Japanese Patent Application No. 2024-180371, No. 2024-180372, No. 2024-180373, No. 2024-180374, and No. 2025-050292, filed on 15 October 2024, claiming the benefit of priority thereunder, and the contents of those patent applications are incorporated herein by reference.

[0002] This disclosure relates to powders containing negative thermal expansion materials, methods for manufacturing negative thermal expansion materials, methods for manufacturing composite materials, and composite materials.

[0003] It is generally known that materials expand with increasing temperature. However, the advanced development of industrial technology in recent years has led to demands to control even the thermal expansion that is inherent to solid materials. (Example: A change in length (strain) of 10 ppm (10) －５ Even slight shape changes, which may seem insignificant from a general perspective, can be a major problem in fields such as semiconductor device manufacturing, where nanometer-level precision is required, or in precision equipment where even slight distortion of components can greatly affect functionality. Furthermore, in devices that combine multiple materials, differences in the thermal expansion of each constituent material can lead to other problems such as interfacial delamination and disconnection.

[0004] On the other hand, there are also materials with negative thermal expansion, in which the lattice volume decreases with increasing temperature (having a negative coefficient of thermal expansion). For example, β-Cu with a monoclinic crystal structure exhibits large negative thermal expansion over a wide temperature range. １．８ Zn ０．２ V ２ O ７ This is known (see Patent Document 1). Furthermore, manganese nitrides exhibiting negative thermal expansion are also known (see Patent Document 2).

[0005] Japanese Patent Publication No. 2019-210198 Japanese Patent Publication No. 2020-011877

[0006] In order to apply negative thermal expansion materials in various fields, it is required to develop a highly practical material containing a negative thermal expansion material with better properties.

[0007] In view of such a situation, the present disclosure is made. One of the purposes thereof is to provide a highly practical material containing a negative thermal expansion material having excellent properties.

[0008] In order to solve the above problems, the powder of a certain aspect of the present disclosure has the general formula (1) Zn ｘ１ T ｘ２ P ｙ１ A ｙ２ O ｚ (T contains at least one element selected from Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho. A contains at least one element selected from Li, Ca, Sr, Ba, Al, Si, V, Ge, Sn, La, Ce, Y, Pr, Nd, Sm. It satisfies 0 ≦ x2 < 2, 0 ≦ y2 ≦ 2, 1.7 ≦ x1 + x2 ≦ 2.3, 1.7 ≦ y1 + y2 ≦ 2.3, 6 ≦ z ≦ 8.) and contains a negative thermal expansion material represented by the formula, and the volume frequency 90% particle size (D ９０ ) is 50 μm or less.

[0009] Another aspect of the present disclosure is a powder. This powder has the general formula (2) Cu ｘ１ T ｘ２ V ｙ１ A ｙ２ O ｚ(T contains at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, and A contains Li, Mg, Ca, Sr, Ba, The material contains a negative thermal expansion material comprising a compound represented by Al, Si, P, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, Y, Pr, Nd, Sm, and satisfying 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8, with a volume frequency of 90% particle size (D ９０ The size is 50 μm or less.

[0010] Another aspect of this disclosure is a method for manufacturing a negative thermal expansion material. This method involves the general formula (1) Zn ｘ１ T ｘ２ P ｙ１ A ｙ２ O ｚ (T is Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K , F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, A is Li, Ca, Sr, Ba, Al, Si, V The method includes the firing temperature when producing a negative thermal expansion material represented by (containing at least one element selected from Ge, Sn, La, Ce, Y, Pr, Nd, and Sm, and satisfying 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8), and the step of adjusting the color of the negative thermal expansion material by adjusting at least one of the volume frequency center particle size and volume frequency 90% particle size of the negative thermal expansion material.

[0011] Another aspect of this disclosure is a method for manufacturing a negative thermal expansion material. This method involves the general formula (2) Cu ｘ１ Tｘ２ V ｙ１ A ｙ２ O ｚ (T contains at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, and A contains Li, Mg, Ca, Sr, Ba, Al, Si, P, Ti, Cr, The method includes adjusting the color of a negative thermal expansion material by adjusting at least one of x, y, and z of a negative thermal expansion material represented by (containing at least one element selected from Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, Y, Pr, Nd, Sm, and satisfying 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8).

[0012] A further aspect of the present disclosure is a method for manufacturing a composite material. This method includes the step of forming a sheet of a mixture of powder containing a negative thermal expansion material and a resin.

[0013] Another aspect of the present disclosure is a composite material comprising a resin and a negative thermal expansion material, having a sheet-like shape, wherein powder of the negative thermal expansion material is dispersed within the resin.

[0014] According to this disclosure, it is possible to provide materials of high practical value, including negative thermal expansion materials with excellent properties.

[0015] This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (1). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (1). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (1). This figure shows the volume frequency center particle size and volume frequency 90% particle size of a powder containing a negative thermal expansion material represented by general formula (1). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (1). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (1). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). This figure shows the particle size distribution of a powder containing a negative thermal expansion material represented by general formula (2). Co ３ BO ５ This figure shows the particle size distribution of the powder. This figure shows the composition, firing temperature, volume frequency center particle size, color, and linear expansion coefficient of the negative thermal expansion materials of Examples 3-1-1 to 3-1-13. This figure shows the relationship between firing temperature, volume frequency center particle size, and color of the negative thermal expansion materials of Examples 3-1-1 to 3-1-13. Zn ２－ｘ Mg ｘ P ２ O ７ This figure shows the linear thermal expansion of a sintered body at (x = 0, 0.2, 0.4, 0.6). Zn １．６ Mg ０．３ X ０．１ P ２ O ７ This figure shows the linear thermal expansion of a sintered body (X = Ca, Sr, Ba). １．９－ｘ Mg ｘ Ba ０．１ P ２ O ７This figure shows the linear thermal expansion of a sintered body at (x = 0.2, 0.3, 0.4). Zn １．６ Mg ０．２ Ba ０．１ Ti ０．１ P ２ O ７ This figure shows the linear thermal expansion of the sintered body (Example 3-1-10). Zn １．６ Mg ０．４－ｘ Ba ｘ P ２ O ７ This figure shows the powder X-ray patterns for (x = 0, 0.1, 0.2, 0.3, 0.4). This figure shows the composition, linear expansion coefficient, and color of the negative thermal expansion materials for Examples 3-2-1 to 3-2-8. This figure plots the colors of the negative thermal expansion materials for Examples 3-2-1 to 3-2-8 on a color wheel. This figure shows the composition, linear expansion coefficient, and color of the negative thermal expansion materials for Examples 3-2-9 to 3-2-15. This figure plots the colors of the negative thermal expansion materials for Examples 3-2-9 to 3-2-15 on a color wheel. This figure shows the linear thermal expansion of the composite material and epoxy resin for Example 4-3. This figure shows the linear thermal expansion of the composite material and epoxy resin for Example 4-4. This figure shows the composition, resin type, volume ratio of negative thermal expansion material to resin, and linear expansion coefficient of the composite materials for Examples 4-1 to 4-5.

[0016] As a first embodiment of this disclosure, a negative thermal expansion material of this disclosure will be described. As a second embodiment of this disclosure, the particle size of the powder of the negative thermal expansion material will be described. As a third embodiment of this disclosure, a technique for adjusting the properties of the powder of the negative thermal expansion material, such as its color, will be described. As a fourth embodiment of this disclosure, a composite material including the negative thermal expansion material will be described.

[0017] (First Embodiment)

[0018] The negative thermal expansion material disclosed herein is based on the general formula (1) Zn ｘ１ T ｘ２ P ｙ１ A ｙ２ O ｚ(T is Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, Select from La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho. The compound may also contain at least one element, where A contains at least one element selected from Li, Ca, Sr, Ba, Al, Si, V, Ge, Sn, La, Ce, Y, Pr, Nd, Sm, and satisfies 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8.

[0019] In general formula (1), x² may satisfy 0 < x² ≤ 1.6. More preferably, x² is 0.05 to 1.6. x² may be 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, or 1 or more. x² may be 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0020] In general formula (1), y2 may satisfy 0 ≤ y2 ≤ 1.8. More preferably, y2 is 0 ≤ y2 ≤ 1.6, and even more preferably, y2 is between 0 and 1.2. y2 may be 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, or 1 or more. y2 may be 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0021] Pyrophosphates are, for example, Mg ２ P ２ O ７ Ca２ P ２ O ７ , Mn ２ P ２ O ７ , Fe ２ P ２ O ７ , Co ２ P ２ O ７ , Ni ２ P ２ O ７ , Cu ２ P ２ O ７ , Zn<000008l>P ２ O ７ etc., many stoichiometric compositions are known to exist and have a flexible crystal structure. For this reason, many elements close to Zn in the periodic table are preferable as T in the general formula (1). For example, Mg, Al, Mn, Fe, Cu, etc. are preferable as T.

[0022] The negative thermal expansion material of the present invention represented by the general formula (1) shows a structural phase transition in the negative thermal expansion temperature range, and since the volume of the low temperature phase is larger than that of the high temperature phase, negative thermal expansion occurs. In the temperature range showing negative thermal expansion, the high temperature phase and the low temperature phase coexist, and it is considered that the ratio changes with temperature. The space group of the structure of the low temperature phase (referred to as the α phase) is I2 / c, and the space group of the structure of the high temperature phase (referred to as the β phase) is considered to be C2 / m. Therefore, those with a high ratio of the α phase on the lower temperature side than the negative thermal expansion temperature range and a high ratio of the β phase on the higher temperature side show a large negative thermal expansion. In particular, it is preferable but not limited to those with a high ratio of I2 / c in the low temperature phase and a high ratio of C2 / m in the high temperature phase.

[0023] According to the known literature so far, for example, Zn ２ P ２ O ７ has also been reported that the space group of the low temperature phase is Ic, so the negative thermal expansion material of the present disclosure may contain a compound of the general formula (1) whose space group is Ic. Also, for example, Mg ２ P ２ O ７ has been reported that the space group of the low temperature phase is B2 １ / c or P2 １ / c, so the negative thermal expansion material of the present disclosure has a space group of B2１ / c or P2 １ It may contain a compound of general formula (1) which is / c. Further, for example, Cu ２ P ２ O ７ In the case of, the space group of the low-temperature phase is reported to be C2 / c, so the negative thermal expansion material of the present disclosure may contain a compound of general formula (1) whose space group is C2 / c.

[0024] Furthermore, the negative thermal expansion material of the present disclosure may contain impurities and the like that are mixed in when using general raw materials and synthesis methods. Since the effect of negative thermal expansion works on volume, if the negative thermal expansion material of the present disclosure is included, it exhibits negative thermal expansion according to its content rate, and thus can be used as a thermal expansion inhibitor or a negative thermal expansion material. Therefore, even a mixture containing impurities and the like is within the scope of the present disclosure as long as it contains the negative thermal expansion material of the present disclosure.

[0025] The negative thermal expansion material of the present disclosure has the general formula (2) Cu ｘ１ T ｘ２ V ｙ１ A ｙ２ O ｚ (T contains at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, A contains at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, P, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, Y, Pr, Nd, Sm, and satisfies 0 ≦ x2 < 2, 0 ≦ y2 ≦ 2, 1.7 ≦ x1 + x2 ≦ 2.3, 1.7 ≦ y1 + y2 ≦ 2.3, 6 ≦ z ≦ 8.) It may contain a compound represented by.

[0026] In general formula (2), x² may be 0 < x² ≤ 2, 0 ≤ x² < 2, or 0 < x² < 2. x² may be 0.05 or greater, 0.1 or greater, 0.2 or greater, 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 or greater, 0.9 or greater, 1 or greater, 1.1 or greater, 1.2 or greater, 1.3 or greater, 1.4 or greater, 1.5 or greater, or 1.6 or greater. x² may be 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less, or 0.05 or less.

[0027] In general formula (2), y2 may be 0.05 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, or 1.6 or more. y2 may also be 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less, or 0.05 or less.

[0028] The negative thermal expansion material disclosed herein is based on the general formula (3) Ti ｘ１ M ｘ２ O ３ The compound may also include the expression (where M contains at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, and satisfies 0 ≤ x² < 2 and 1.7 ≤ x¹ + x² ≤ 2.3).

[0029] In general formula (3), x² may be 0.1 or greater, 0.2 or greater, 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 or greater, 0.9 or greater, 1 or greater, 1.1 or greater, 1.2 or greater, 1.3 or greater, 1.4 or greater, 1.5 or greater, or 1.6 or greater. x² may be 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0030] The negative thermal expansion material of this disclosure has a negative linear expansion coefficient at the above particle size in at least a portion of the temperature range from 200K to 380K, preferably having a linear expansion coefficient of α = -3.5 ppm / K or less, more preferably α = -6 ppm / K or less, even more preferably α = -10 ppm / K or less, and even more preferably -20 ppm / K or less. The linear expansion coefficient of the powder may be -1 ppm / K or less, -2 ppm / K or less, -3 ppm / K or less, -4 ppm / K or less, -5 ppm / K or less, -7 ppm / K or less, -8 ppm / K or less, -9 ppm / K or less, -12 ppm / K or less, -15 ppm / K or less, -30 ppm / K or less, or -40 ppm / K or less. The material only needs to have the above-mentioned negative coefficient of linear expansion in at least a portion of the temperature range between 200K and 380K, but does not need to have the above-mentioned negative coefficient of linear expansion in at least a portion of the temperature range between 200K and 380K. The "at least a portion of the temperature range" may be any temperature range, for example, 1K, or 10K, 20K, 30K, 40K, 50K, or 100K.

[0031] In this disclosure, the coefficient of linear expansion of the powder is evaluated as follows. Measuring the thermal expansion characteristics of a single fine particle is technically difficult, and attempting to measure the thermal expansion characteristics of sintered fine particles may cause the negative thermal expansion material to change during the sintering process. Considering that negative thermal expansion materials are mainly used to suppress thermal expansion by compounding them with materials such as resins, it is reasonable to evaluate the coefficient of linear expansion of the powder by measuring the extent to which thermal expansion is suppressed in a composite material in which the powder is compounded with a general resin such as epoxy resin. Therefore, in this disclosure, the coefficient of linear expansion of the powder is evaluated according to a composite rule that predicts the coefficient of linear expansion of the composite material by apportioning the coefficients of linear expansion of each component based on the volume ratio of the base material and the powder dispersed in the base material.

[0032] The combined rule is that the volume ratio of the base and the coefficient of linear expansion are given by ν. ｍ , α ｍ ν is used to determine the volume ratio and linear expansion coefficient of the fine particles, respectively. ｆ , α ｆ The coefficient of linear thermal expansion of the composite material is α ｃ As α ｃ =ν ｍ α ｍ +ν ｆ α ｆ The coefficient of linear thermal expansion of composite materials is predicted from the following relationship: Here, ν ｍ +ν ｆ = 1. Based on this equation, α ｆ = (α ｃ -ν ｍ α ｍ ) / ν ｆ The coefficient of linear expansion of the powder is evaluated. α ｆ All other parameters can be easily measured. According to this method, the linear expansion coefficient α of the powder can be determined regardless of the type of base material. ｆ Since the same value can be obtained as the coefficient of linear expansion α ｍ Any material can be used as a base material as long as its coefficient of thermal expansion α is known or measurable. ｍ Depending on the volume ratio ν ｍ ν ｍ +ν ｆIt can be arbitrarily changed within the range that satisfies = 1. However, when using metals or ceramics as the base material, the heat treatment temperature for composite formation is higher than that of resins, so the negative thermal expansion material may be altered during the composite formation process, and a value lower than the negative thermal expansion value that should be shown may be observed, as reported in past literature (e.g., "Matrix-filler interfaces and physical properties of metal matrix composites with negative thermal expansion manganese nitride", K. Takenaka, K. Kuzuoka, and N. Sugimoto, J. Appl. Phys. 118, 084902 (2015)). Therefore, it is undesirable for the purpose of evaluating the linear expansion coefficient of powders. For this reason, it is preferable to use epoxy resin as the base material. In the examples described below, the linear expansion coefficient of powders was evaluated using composite materials formed by compounding powders with epoxy resin as the base material. α at 200K to 380K ｆ The average value of α is taken as the linear expansion coefficient of the powder in the range of 200K to 380K. Since the temperature range in which the powder exhibits large negative thermal expansion can vary depending on the chemical composition, the temperature range for evaluating thermal expansion may be appropriately changed in order to properly evaluate the powder's ability to suppress thermal expansion. For example, ranges such as 250K to 350K, 200K to 350K, and 300K to 380K may be preferred. α at both ends of the temperature range ｆ The average value may be used as the coefficient of linear expansion of the powder within that temperature range.

[0033] Negative thermal expansion materials may be manufactured by a solid-phase reaction method or by a spray-drying method. In the former case, powders of raw materials such as oxides containing the constituent elements of the compounds represented by general formulas (1) to (3) are weighed in a specified molar ratio, mixed in an agate mortar and pestle, and then calcined in an alumina crucible. In the latter case, an aqueous solution containing at least one of the compounds represented by general formulas (1) to (3) and their raw materials, and at least one of an acid, salt, and organometallic compound is spray-dried. Negative thermal expansion materials manufactured by solid-phase reactions or the like may be pulverized and then heated to recrystallize them.

[0034] The spray drying method yields particles with smaller particle sizes, a narrower particle size distribution, and an isotropic shape compared to conventional solid-phase reaction methods. This allows for powder pulverization with significantly less mechanical load compared to pulverizing large crystals obtained with conventional solid-phase reaction methods, resulting in a group of fine particles that maintain negative thermal expansion properties. Further adjustments to particle size and particle size distribution can be made by incorporating classification processes such as sieving.

[0035] The acid may be an organic acid or an inorganic acid. Examples of organic acids include citric acid and acetic acid. The salt may be a salt of an organic acid and an alkali, or a salt of an inorganic acid and an alkali. Examples of salts include metal nitrates, metal acetates, metal sulfates, metal chlorides, and metal fatty acids. Examples of organometallic compounds include metal alkoxides and metal acetylacetonates. An aqueous solution of the metal dissolved in nitric acid, hydrochloric acid, sulfuric acid, etc. may also be used.

[0036] When preparing an aqueous solution, the compounds represented by general formulas (1) to (3) themselves may be dissolved, or the raw materials of the compounds represented by general formulas (1) to (3) may be dissolved.

[0037] (Second Embodiment) The negative thermal expansion material of this disclosure has excellent negative thermal expansion properties even in the form of a fine powder. Therefore, it can effectively suppress the thermal expansion of components such as resin films, adhesives, interlayer fillers, and substrates that are expected to be used in the field of electronic devices at a size of several micrometers.

[0038] To suppress negative thermal expansion in such minute components, it is necessary not only for the average particle size of the negative thermal expansion material powder to be small, but also for there to be few coarse particles. From this viewpoint, the negative thermal expansion material powder is defined as having a volume frequency of 90% particle size (D ９０ The inventors realized that it is appropriate to define it by the upper limit of ).

[0039] The powder according to the second embodiment of this disclosure has a volume frequency of 90% particle size (D ９０The particle size is 50 μm or less. The volume frequency 90% particle size is measured by the laser diffraction / scattering particle size distribution evaluation method. The volume frequency 90% particle size of the negative thermal expansion material of this disclosure may be 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, 11 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, 0.2 μm or less, or 0.1 μm or less.

[0040] The powder according to the second embodiment of this disclosure may have a volume frequency 90% particle size of 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, 3.5 μm or more, 4 μm or more, 4.5 μm or more, 5 μm or more, 5.5 μm or more, 6 μm or more, 6.5 μm or more, 7 μm or more, 7.5 μm or more, 8 μm or more, 8.5 μm or more, 9 μm or more, 9.5 μm or more, or 10 μm or more.

[0041] In order to further enhance the effect of suppressing negative thermal expansion by mixing with minute components, the volume frequency center particle size (D) of the powder according to the second embodiment of this disclosure ５０ ) may be 20 μm or less, 15 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, 0.2 μm or less, 0.1 μm or less, 0.09 μm or less, 0.08 μm or less, 0.07 μm or less, 0.06 μm or less, 0.05 μm or less, 0.04 μm or less, 0.03 μm or less, 0.02 μm or less, or 0.01 μm or less.

[0042] The volume frequency center particle size of the powder according to the second embodiment of this disclosure may be 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, or 10 μm or more.

[0043] The above numerical ranges may be any combination as long as the lower limit of the 90% volume frequency particle size is smaller than the upper limit of the 90% volume frequency particle size, the lower limit of the central volume frequency particle size is smaller than the upper limit of the central volume frequency particle size, the upper limit of the central volume frequency particle size is smaller than the upper limit of the 90% volume frequency particle size, and the lower limit of the central volume frequency particle size is smaller than the lower limit of the 90% volume frequency particle size.

[0044] The powder according to the second embodiment of this disclosure may be produced by a solid-phase reaction method or a spray drying method, or by grinding the powder produced by the solid-phase reaction method or spray drying method with a planetary ball mill or the like.

[0045] The powder according to the second embodiment of this disclosure may contain at least one of the negative thermal expansion materials represented by general formulas (1) to (3).

[0046] The volume frequency 90% particle size of the powder according to the second embodiment of this disclosure may be 4 μm or less. Patent Document 2 describes manganese nitride Mn synthesized by a solid-phase reaction method. ３ Ga ０．９ Sn ０．１ N ０．９ It is stated that the volume frequency 90% particle size of the powder obtained by further wet grinding of the coarse powder obtained by grinding the material is 4.10 μm. By setting the volume frequency 90% particle size to 4 μm or less, negative thermal expansion in minute components can be suppressed more effectively than the manganese nitride described in Patent Document 2. It should be noted that the negative thermal expansion material represented by general formulas (1) to (3) is not described in Patent Document 2, and setting the volume frequency 90% particle size of the powder of the negative thermal expansion material represented by general formulas (1) to (3) to the above numerical range, for example, 50 μm or less, was not something that a person skilled in the art could easily conceive based on Patent Document 2.

[0047] [Example 2-1] Powder of a negative thermal expansion material represented by general formula (1) was manufactured and its particle size distribution was measured. The volume frequency 90% particle sizes of several samples were 3.49 μm, 3.10 μm, 2.81 μm, 2.68 μm, 2.47 μm, 2.16 μm, 1.49 μm, 1.46 μm, and 1.08 μm, and the volume frequency center particle sizes were 1.50 μm, 1.32 μm, 1.17 μm, 1.16 μm, 0.82 μm, 0.77 μm, 0.63 μm, and 0.44 μm. Figure 1 shows the particle size distribution of powder obtained by hydrothermally synthesizing and calcining the negative thermal expansion material represented by general formula (1). Zn shown in Figure 1 ２ P ２ O ７ The volume frequency median particle size of the powder is 2.10 μm, and the volume frequency 90% particle size is 4.86 μm. Figure 2 shows the particle size distribution of the powder obtained by hydrothermally synthesizing a negative thermal expansion material represented by general formula (1) and calcining it at 1000°C. Figure 2 shows Zn １．６ Mg ０．４ P ２ O ７ The volume frequency center particle size is 4.36 μm, and the volume frequency 90% particle size is 7.53 μm. Figure 3 shows the particle size distribution of powder synthesized by solid-phase reaction of the negative thermal expansion material represented by general formula (2), powder obtained by grinding the powder synthesized by solid-phase reaction, and powder obtained by grinding and re-calcining the powder synthesized by solid-phase reaction. Figure 4 shows the volume frequency center particle size and volume frequency 90% particle size of these powders. The volume frequency 90% particle sizes of these powders are 9.58 μm, 1.96 μm, and 3.19 μm, respectively, and the volume frequency center particle sizes are 5.61 μm, 0.98 μm, and 1.45 μm, respectively. Figure 5 shows the particle size distribution of powder obtained by hydrothermally synthesizing and calcining the negative thermal expansion material represented by general formula (1). Zn shown in Figure 5 １．７ Mg ０．３ P ２ O ７ The volume frequency center particle size is 7.5 μm, and the volume frequency 90% particle size is 13.5 μm. Figure 6 shows the particle size distribution of powder obtained by hydrothermally synthesizing and calcining a negative thermal expansion material represented by general formula (1). The Zn shown in Figure 6 １．７ Mg ０．２５ Al ０．０５ P ２ O ７The volume frequency central particle size is 1.4 μm, and the volume frequency 90% particle size is 3.2 μm.

[0048] The volume frequency 90% particle size of the powder containing the negative thermal expansion material represented by general formula (1) may be 13.5 μm or less, 9.58 μm or less, 7.53 μm or less, 4.86 μm or less, 3.49 μm or less, 3.2 μm or less, 3.19 μm or less, 3.10 μm or less, 2.81 μm or less, 2.68 μm or less, 2.47 μm or less, 2.16 μm or less, 1.96 μm or less, 1.49 μm or less, 1.46 μm or less, or 1.08 μm or less. Furthermore, the volume frequency center particle size of the powder containing the negative thermal expansion material represented by general formula (1) may be 7.5 μm or less, 5.61 μm or less, 4.36 μm or less, 2.10 μm or less, 1.50 μm or less, 1.45 μm or less, 1.4 μm or less, 1.32 μm or less, 1.17 μm or less, 1.16 μm or less, 0.98 μm or less, 0.82 μm or less, 0.77 μm or less, 0.63 μm or less, or 0.44 μm or less.

[0049] [Example 2-2] Powder of a negative thermal expansion material represented by general formula (2) was manufactured and its particle size distribution was measured. Figures 7 to 16 show the particle size distribution of powder containing the negative thermal expansion material represented by general formula (2). Figure 7 shows Cu １．８ Zn ０．２ VPO ７ The volume frequency median particle size of the powder is 2.08 μm, the volume frequency 90% particle size is 5.73 μm, and the coefficient of linear expansion is -16.2 ppm / K. Figure 8 shows Cu １．８ Zn ０．２ VPO ７ The volume frequency median particle size of the powder is 2.04 μm, the volume frequency 90% particle size is 4.89 μm, and the coefficient of linear expansion is -17.0 ppm / K. Figure 9 shows Cu １．８ Zn ０．２ VPO ７ The volume frequency median particle size of the powder is 1.03 μm, the volume frequency 90% particle size is 2.36 μm, and the coefficient of linear expansion is -19.2 ppm / K. Figure 10 shows Cu １．８ Zn ０．２ VPO ７ The volume frequency median particle size of the powder is 7.75 μm, the volume frequency 90% particle size is 23.47 μm, and the coefficient of linear expansion is -15.2 ppm / K. Figure 11 shows Cu１．８ Zn ０．２ V ０．８ P １．２ O ７ The volume frequency median particle size of the powder is 1.43 μm, the volume frequency 90% particle size is 3.20 μm, and the coefficient of linear expansion is -17.7 ppm / K. Figure 12 shows Cu １．８ Zn ０．２ V １．５ P ０．５ O ７ The volume frequency median particle size of the powder is 7.48 μm, the volume frequency 90% particle size is 12.54 μm, and the coefficient of linear expansion is -14.4 ppm / K. Figure 13 shows Cu １．８ Zn ０．２ V ０．５ P １．５ O ７ The volume frequency median particle size of the powder is 6.74 μm, the volume frequency 90% particle size is 12.98 μm, and the coefficient of linear expansion is -23.2 ppm / K. Figure 14 shows Cu １．８ Zn ０．２ V ０．３ P １．７ O ７ The volume frequency median particle size of the powder is 10.39 μm, and the volume frequency 90% particle size is 21.04 μm. Figure 15 shows Cu １．９ Ca ０．１ V ２ O ７ The volume frequency median particle size of the powder is 4.61 μm, the volume frequency 90% particle size is 9.27 μm, and the coefficient of linear expansion is -28.4 ppm / K. Figure 16 shows Cu １．６ Ca ０．４ V ２ O ７ The volume frequency median particle size of the powder is 3.79 μm, the volume frequency 90% particle size is 6.77 μm, and the linear expansion coefficient is -16.4 ppm / K. The negative thermal expansion material powders shown in Figures 7-14 were synthesized by the solid-phase reaction method, while the negative thermal expansion material powders shown in Figures 15-16 were synthesized by the spray-drying method. The linear expansion coefficients of each sample were estimated by assuming a composite rule based on the linear thermal expansion measurement results of epoxy resins containing the powders, as explained in the first embodiment.

[0050] The volume frequency 90% particle size of the powder containing the negative thermal expansion material represented by general formula (2) may be 23.47 μm or less, 21.04 μm or less, 12.98 μm or less, 12.54 μm or less, 9.27 μm or less, 6.77 μm or less, 5.73 μm or less, 4.89 μm or less, 3.20 μm or less, or 2.36 μm or less. In addition, the volume frequency center particle size of the powder containing the negative thermal expansion material represented by general formula (2) may be 10.39 μm or less, 7.75 μm or less, 7.48 μm or less, 6.74 μm or less, 4.61 μm or less, 3.79 μm or less, 2.08 μm or less, 2.04 μm or less, 1.43 μm or less, or 1.03 μm or less.

[0051] The powder according to the second embodiment of this disclosure may include a negative thermal expansion material represented by general formula (3). The volume frequency 90% particle size of the powder containing the negative thermal expansion material represented by general formula (3) may be within the numerical range described above, or it may be the same as that of the powder containing the negative thermal expansion material represented by general formula (1) or (2). The volume frequency center particle size of the powder containing the negative thermal expansion material represented by general formula (3) may be within the numerical range described above, or it may be the same as that of the powder containing the negative thermal expansion material represented by general formula (1) or (2).

[0052] [Example 2-3] Co ３ BO ５ The powder was manufactured and its particle size distribution was measured. Figure 17 shows Co ３ BO ５ This shows the particle size distribution of the powder. Figure 17 shows Co ３ BO ５ The volume frequency median particle size of the powder is 3.84 μm, and the volume frequency 90% particle size is 6.35 μm.

[0053] (Third Embodiment) As described in the first and second embodiments, the negative thermal expansion material represented by general formulas (1) to (3) has negative thermal expansion properties over a wide range of compositions. Furthermore, by changing the composition, properties such as the coefficient of linear expansion, electrical resistivity, electrostriction constant, and color can be changed. Therefore, by adjusting the composition of the negative thermal expansion material of general formulas (1) to (3), it is possible to manufacture a negative thermal expansion material having properties such as the coefficient of linear expansion, electrical resistivity, electrostriction constant, and color that meet the required specifications.

[0054] The negative thermal expansion material represented by general formula (1) exhibits a color between white and gray, and its luminance on the grayscale can vary depending on its composition. The luminance on the grayscale takes a value between 0 (black, representing the absence of any light) and 1 (white, representing the maximum amount of light). When the luminance on the grayscale is represented in 256 levels, black is 0 and white is 255.

[0055] By adjusting T, A, x1, x2, y1, and y2 in general formula (1), the color of the negative thermal expansion material represented by general formula (1) can be precisely adjusted to any color between white and gray. Furthermore, the properties of the negative thermal expansion material represented by general formula (1), such as the coefficient of linear expansion, electrical resistivity, and electrostrictive constant, can also be precisely adjusted.

[0056] By adjusting the conditions for manufacturing the negative thermal expansion material represented by general formula (1), the color of the negative thermal expansion material represented by general formula (1) can be precisely adjusted to any color between white and gray. Furthermore, the properties of the negative thermal expansion material represented by general formula (1), such as the coefficient of linear expansion, electrical resistivity, and electrostrictive constant, can also be precisely adjusted. The conditions may relate to the type of manufacturing method, firing temperature, firing time, grinding method, grinding time, and grinding temperature. The brightness of the negative thermal expansion material represented by general formula (1) decreases as the firing temperature increases.

[0057] By adjusting the particle size of the negative thermal expansion material powder represented by general formula (1), the color of the negative thermal expansion material represented by general formula (1) can be precisely adjusted to any color between white and gray. Furthermore, the properties of the negative thermal expansion material represented by general formula (1), such as the coefficient of linear expansion, electrical resistivity, and electrostrictive constant, can also be precisely adjusted. The particle size of the powder may be expressed by the volume frequency center particle size or the volume frequency 90% particle size. The brightness of the negative thermal expansion material represented by general formula (1) decreases as the volume frequency center particle size decreases.

[0058] The negative thermal expansion material represented by general formula (2) exhibits a color between light blue and reddish-purple, and its hue and lightness on the color wheel can vary depending on its composition. The color wheel is a circular arrangement of all hues in order. The correspondence between hue angles and colors is as follows: 0° is red (#FF0000), 15° is vermilion (#FF4000), 30° is orange (#FF8000), 45° is golden yellow (#FFBF00), 60° is yellow (#FFFF00), 75° is light yellow-green (#BFF00), 90° is yellow-green (#80FF00), 105° is light green (#40FF00), 120° is green (#00FF00), 135° is cobalt green (#00FF40), 150° is emerald green (#00FF80), and 165° is blue-green (#00FFBF). 180° is cyan (#00FFFF), 195° is cerulean blue (#00BFFF), 210° is blue (#0080FF), 225° is cobalt blue (#0040FF), 240° is ultramarine (#0000FF), 255° is hyacinth (#4000FF), 270° is violet (#8000FF), 285° is purple (#BF00FF), 300° is magenta (#FF00FF), 315° is reddish-purple (#FF00BF), 330° is ruby ​​red (#FF0080), and 345° is carmine (#FF0040).

[0059] By adjusting T, A, x1, x2, y1, and y2 in general formula (2), the hue of the negative thermal expansion material represented by general formula (2) can be precisely adjusted to any hue between cyan and purple. Furthermore, the saturation and brightness can also be adjusted arbitrarily. Additionally, the properties of the negative thermal expansion material represented by general formula (2), such as the coefficient of linear expansion, electrical resistivity, and electrostrictive constant, can also be precisely adjusted.

[0060] The properties of the negative thermal expansion material represented by general formula (2), such as color, linear expansion coefficient, electrical resistivity, and electrostrictive constant, may be adjusted by adjusting the conditions and powder particle size during the manufacturing process. The conditions may relate to the type of manufacturing method, firing temperature, firing time, grinding method, grinding time, and grinding temperature. The powder particle size may be expressed by volume frequency center particle size or volume frequency 90% particle size.

[0061] The properties of the negative thermal expansion material represented by general formula (3), such as color, linear expansion coefficient, electrical resistivity, and electrostrictive constant, may be adjusted by adjusting M and x in general formula (3), the conditions for manufacturing the negative thermal expansion material represented by general formula (3), and the particle size of the powder. The conditions may relate to the type of manufacturing method, firing temperature, firing time, grinding method, grinding time, and grinding temperature. The particle size of the powder may be expressed by the volume frequency center particle size or the volume frequency 90% particle size.

[0062] [Example 3-1] A negative thermal expansion material represented by general formula (1) was manufactured and its properties, such as color, were measured. Figure 18 shows the composition, firing temperature, volume frequency, central particle size, color, and linear expansion coefficient of the negative thermal expansion materials of Examples 3-1-1 to 3-1-13. Note that the color was observed with the naked eye and may contain some error. Also, the actual color of the negative thermal expansion material is not perfectly grayscale and contains some color, sometimes appearing as bluish white, bluish gray, reddish white, or reddish gray. In this figure, the color of the negative thermal expansion material is represented by the brightness when the color of the negative thermal expansion material is converted to grayscale. The linear expansion coefficient is the average value of the linear expansion coefficient αf at 250-350K, estimated from the measured value of the linear thermal expansion of a composite containing 30 vol% of the negative thermal expansion material powder and 70 vol% of the epoxy resin, assuming the composite rule described above.

[0063] Examples 3-1-1 to 3-1-4 use Zn １．６ Mg ０．４ P ２ O ７ These were manufactured under different conditions. Examples 3-1-5 to 3-1-11 are Zn ２ P ２ O ７ In this example, some of the Zn sites are replaced with Mg, Ba, Sr, Ca, Ti, etc. Example 3-1-12 is a Zn product fired at a firing temperature of 875°C. １．７ Mg ０．３ P ２ O ７ This is the result of manufacturing Zn at a firing temperature of 800°C. Example 3-1-13 is a product of Zn １．７ Mg ０．２５ Al ０．０５ P ２ O ７ This is the product that was manufactured.

[0064] Figure 19 shows the relationship between firing temperature, volume frequency central particle size, and color of the negative thermal expansion materials in Examples 3-1-1 to 3-1-13. The brightness of the negative thermal expansion material, represented by general formula (1), decreases as the firing temperature increases and as the volume frequency central particle size of the powder decreases.

[0065] Figure 20 shows Zn ２－ｘ Mg ｘ P ２ O ７ Figure 21 shows the linear thermal expansion of the sintered body at (x = 0, 0.2, 0.4, 0.6). １．６ Mg ０．３ X ０．１ P ２ O ７ This shows the linear thermal expansion of a sintered body (X = Ca, Sr, Ba). Figure 22 shows Zn １．９－ｘ Mg ｘ Ba ０．１ P ２ O ７ Figure 23 shows the linear thermal expansion of the sintered body at (x = 0.2, 0.3, 0.4). １．６ Mg ０．２ Ba ０．１ Ti ０．１ P ２ O ７ The linear thermal expansion of the sintered body of (Example 3-1-10) is shown. Figure 24 shows Zn １．６ Mg ０．４－ｘ Ba ｘ P ２ O ７ The powder X-ray patterns for (x = 0, 0.1, 0.2, 0.3, 0.4) are shown. It was confirmed that all of the negative thermal expansion materials in Example 3-1 have similar structures and exhibit negative thermal expansion characteristics. Furthermore, it was confirmed that the negative thermal expansion characteristics change depending on the composition of the negative thermal expansion material.

[0066] [Example 3-2] A negative thermal expansion material represented by general formula (2) was manufactured and its properties, such as color, were measured. Figure 25 shows the composition, linear expansion coefficient, and color of the negative thermal expansion materials of Examples 3-2-1 to 3-2-8. Note that the color was determined by visual inspection and may contain some error. Also, since it is not possible to publish the color drawings, the color drawings have been converted to grayscale drawings using a common method and are published here. The same applies to Figures 26 to 28.

[0067] Examples 3-2-1 to 3-2-8 are Cu １．８ Zn ０．２ V ２－ｙ P ｙ O ７ This is the result of adjusting y between 0.2 and 2.0.

[0068] Figure 26 is a plot of the colors of the negative thermal expansion materials of Examples 3-2-1 to 3-2-8 on the color wheel. The colors of Examples 3-1 (y=0.2), 3-2 (y=0.4), 3-3 (y=0.6), 3-4 (y=0.8), 3-5 (y=1.0), 3-6 (y=1.5), 3-7 (y=1.8), and 3-8 (y=2.0) are Cu ２ V ２ O ７ Increasing the amount (y) that replaces the V-site with P causes a counterclockwise change on the color wheel. Therefore, it was confirmed that the color of the negative thermal expansion material can be precisely adjusted to any color between reddish-purple and light blue by adjusting the composition of the negative thermal expansion material represented by general formula (2).

[0069] Figure 27 shows the composition, linear expansion coefficient, and color of the negative thermal expansion materials of Examples 3-2-9 to 3-2-15. Figure 28 is a plot of the colors of the negative thermal expansion materials of Examples 3-2-9 to 3-2-15 on a color wheel.

[0070] Example 3-2-10 is Example 3-2-9 (Cu ２ V ２ O ７ ) is a compound in which a portion of the Cu site is replaced with Mg. Example 3-2-14 is a compound in which a portion of the Cu site of Example 3-2-9 (Cu ２ V ２ O ７ ) is a modified version in which a portion of the Cu site is replaced with Ca. Example 3-2-15 is a modified version of Example 3-2-9 (Cu ２ V ２ O ７This is a compound in which a portion of the Cu site is replaced with Sr. When a portion of the Cu site is replaced with Mg, the color change on the color wheel is small; when a portion of the Cu site is replaced with Ca, the color changes counterclockwise on the color wheel; and when a portion of the Cu site is replaced with Sr, the color changes clockwise on the color wheel.

[0071] Examples 3-2-11 and 3-2-13 are based on Example 3-2-9 (Cu ２ V ２ O ７ This is a compound in which some of the Cu sites are replaced with Ca and Mg. In Example 3-2-11, where the amount of Mg substitution is greater, the color changes counterclockwise on the color wheel, while in Example 3-2-13, where the amount of Mg substitution is less, the color changes clockwise on the color wheel.

[0072] Example 3-2-12 is Example 3-2-9 (Cu ２ V ２ O ７ This is a compound in which a portion of the Cu site is replaced with Ca and a portion of the V site is replaced with P. In Example 3-2-12, the color changes counterclockwise on the color wheel.

[0073] It was confirmed that all of the negative thermal expansion materials in Examples 3-2-1 to 3-2-15 possessed large negative thermal expansion characteristics.

[0074] (Fourth Embodiment) As a fourth embodiment of the present disclosure, a composite material is described which is formed into a sheet from a mixture of powder containing the negative thermal expansion material described in the first to third embodiments and a resin.

[0075] The composite material of the fourth embodiment of the present disclosure comprises a negative thermal expansion material and a resin, and has a sheet-like shape in which powder of the negative thermal expansion material is dispersed in the resin.

[0076] The composite material of the fourth embodiment of this disclosure may include at least one of the compounds represented by the above general formulas (1), (2), and (3). The composite material of the fourth embodiment of this disclosure may also include negative thermal expansion materials other than the compounds represented by the above general formulas (1), (2), and (3).

[0077] The composite material of the fourth embodiment of this disclosure can be used as an actuator material. For example, Cu ２ V ２ O ７ Normally, it takes the form of a dielectric α phase (orthorhombic Fdd2), but it is energetically in conflict with a non-dielectric β phase (monoclinic C2 / c), and if some of the Cu sites are replaced with Zn, a phase transition to the β phase occurs (J. Pommer et al., Phys. Rev. B67 (2003) 214410). Near the phase boundary, a phase transition from the β phase to the α phase can be induced by an electric field. Therefore, the inventors conceived of inducing a phase transition accompanied by a volume change with an electric field and devised an actuator material containing a compound represented by general formula (2). The actuator material of this disclosure refers to a material that changes its volume or generates strain in response to an electric field, magnetic field, heat / cold, light, etc., and includes, for example, a material that generates strain when an electric field is applied or changes its own volume in response to a temperature change. Negative thermal expansion materials represented by general formula (1) and general formula (3) can also be used as actuator materials in a similar manner.

[0078] In the composite material of the fourth embodiment of this disclosure, a negative thermal expansion material is dispersed in the base resin. Since the resin has high resistance, a high electric field can be applied to the composite material. This improves the performance as an actuator.

[0079] In the composite material of the fourth embodiment of this disclosure, the resin may be any type of thermoplastic resin, thermosetting resin, etc. The resin may also include epoxy resin, phenolic resin, fluororesin, acrylic resin, acrylonitrile butadiene resin, polycarbonate, polyimide, polyamideimide, polypropylene, polyamide, polyethylene, polyethylene terephthalate, etc.

[0080] The composite material of the fourth embodiment of this disclosure may have the shape of a sheet, plate, film, etc. The thickness of the composite material of the fourth embodiment of this disclosure may be 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, 100 μm or more, 200 μm or more, 300 μm or more, 400 μm or more, 500 μm or more, 600 μm or more, 700 μm or more, 800 μm or more, 900 μm or more, or 1 mm or more. The thickness of the composite material may be 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, 3 mm or less, 2 mm or less, 1 mm or less, 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, 300 μm or less, 200 μm or less, or 100 μm or less.

[0081] In the actuator material of the fourth embodiment of this disclosure, the mixture of the resin and the powder of the negative thermal expansion material contains 10% by volume or more of powder based on the total volume of the mixture. The mixture may also contain 1% by volume or more, 5% by volume or more, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, 60% by volume or more, 70% by volume or more, 80% by volume or more, or 90% by volume or more of powder based on the total volume of the mixture. The mixture may also contain 99% by volume or less, 95% by volume or less, 90% by volume or less, 80% by volume or less, 70% by volume or less, 60% by volume or less, 50% by volume or less, 40% by volume or less, 30% by volume or less, 20% by volume or less, or 10% by volume or less of powder based on the total volume of the mixture.

[0082] The electrical resistivity of the composite material in the fourth embodiment of this disclosure is 10 ６ It may be greater than or equal to Ωcm. The electrical resistivity of the composite material of the first to fourth embodiments of this disclosure is 10 ７ Ωcm or more, 10 ８ Ωcm or more, 10 ９ Ωcm or more, 10 １０ Ωcm or more, 10 １１ Ωcm or more, 10 １２ It may be greater than Ωcm.

[0083] The absolute value of the electrostrictive constant of the composite material in the fourth embodiment of this disclosure is 10－２４ I understand ２ / V ２ It may be greater than or equal to 10. The absolute value of the electrostrictive constant of the composite material in the fourth embodiment of this disclosure is 10 －２２ I understand ２ / V ２ The above 10 －２０ I understand ２ / V ２ The above 10 －１８ I understand ２ / V ２ The above 10 －１６ I understand ２ / V ２ The above is also acceptable. Here, the electrostriction constant M is defined as ΔL / L = M × E² (ΔL / L: line strain, E: electric field strength).

[0084] The composite material of the fourth embodiment of this disclosure may be flexible. In this case, the sheet-like composite material can be used in a deformed state. The composite material of the fourth embodiment of this disclosure may not be flexible. In this case, the composite material can be used while maintaining its sheet-like form.

[0085] The properties of the composite material of the fourth embodiment of this disclosure, such as the coefficient of linear expansion, electrical resistivity, electrostrictive constant, and whether or not it is flexible, may be adjusted according to the specifications. The properties of the composite material of the fourth embodiment of this disclosure may be adjusted by the type and composition of the negative thermal expansion material, the type of resin, the content of the resin and the negative thermal expansion material, the sheet thickness, the molding method, and so on.

[0086] A method for producing a composite material according to a fourth embodiment of the present disclosure includes the step of molding a mixture obtained by mixing a powder containing a negative thermal expansion material with a resin.

[0087] The method for molding the mixture may be any method capable of molding the resin into a sheet. For example, the mixture containing the resin and a negative thermal expansion material may be molded into a sheet using an extruder or the like.

[0088] [Example 4] A composite material was manufactured according to the method for manufacturing a composite material of the fourth embodiment of the present disclosure. Zn １．６５ Mg ０．２５ Ba ０．０５ Sr ０．０５ P ２ O７ (Example 4-1), Zn １．６ Mg ０．３ Ba ０．１ P ２ O ７ (Example 4-2), Zn １．７ Mg ０．３ P ２ O ７ (Example 4-3), Zn １．７ Mg ０．２５ Al ０．０５ P ２ O ７ (Example 4-4), Cu １．９ Sr ０．１ V ２ O ７ (Examples 4-5) were fired at 875°C to prepare the negative thermal expansion material powder. The negative thermal expansion material powder and epoxy resin (a two-component mixture of ADEKA's base material (EP-4100) and curing agent (EH-105L)) were mixed in a volume ratio of 30:70 and molded into a sheet with a thickness of 0.5 to 1.0 mm. The linear thermal expansion of the composite material was measured and the linear expansion coefficient of the negative thermal expansion material was calculated. As described above, the linear expansion coefficient of the negative thermal expansion material was calculated from the linear expansion coefficient of the composite material by assuming the composite law.

[0089] Figure 29 shows the linear thermal expansion of the composite material and epoxy resin in Example 4-3. Figure 30 shows the linear thermal expansion of the composite material and epoxy resin in Example 4-4. Figure 31 shows the composition, resin type, volume ratio of negative thermal expansion material to resin, and linear expansion coefficient of the composite materials in Examples 4-1 to 4-5. The linear expansion coefficients of the negative thermal expansion materials in the composite materials of Examples 4-1 to 4-4 were -64.8 ppm / K, -51.6 ppm / K, -54.5 ppm / K, and -59.2 ppm / K, respectively. In the composite material of Example 4-5, the negative thermal expansion material was a mixture of α phase (Fdd2) and β phase (C2 / c), and the linear expansion coefficient was -16.8 ppm / K. It was confirmed that these negative thermal expansion materials have large negative thermal expansion characteristics.

[0090] The following are preferred examples of negative thermal expansion materials included in the present invention. It goes without saying that the negative thermal expansion materials included in the present invention are not limited to these. Furthermore, materials in which some of the oxygen atoms contained in the negative thermal expansion materials described below are missing or present in excess can also be cited as preferred examples. Additionally, materials exhibiting compositional fluctuations that may occur when using general raw materials and manufacturing methods can also be cited as preferred examples.

[0091] General formula (1) Zn １．５５～１．７５ Mg ０．２５～０．４５ P ２ O ７ Zn １．５～１．７ Mg ０．２５～０．３５ Ba ０．０５～０．１５ P ２ O ７ Zn １．５～１．７ Mg ０．１５～０．２５ Ba ０．１５～０．２５ P ２ O ７ Zn １．５～１．７ Mg ０．０５～０．１５ Ba ０．２５～０．３５ P ２ O ７ Zn １．５～１．７ Mg ０～０．０５ Ba ０．３５～０．４５ P ２ O ７ Zn １．５～１．７ Mg ０．２５～０．３５ Sr ０．０５～０．１５ P ２ O ７ Zn １．５～１．７ Mg ０．２５～０．３５ Ca ０．０５～０．１５ P ２ O ７ Zn １．５～１．７ Mg ０．１５～０．２５ Ba ０．０５～０．１５ Ti ０．０５～０．１５ P ２ O ７ Zn １．５５～１．７５ Mg ０．２～０．３ Ba ０．０１～０．０９ Sr ０．０１～０．０９ P ２ O ７

[0092] General formula (2) Cu １．７５～１．８５ Zn ０．１５～０．２５ V １．９５～２P ０～０．０５ O ７ Cổ １．７５～１．８５ Zhn ０．１５～０．２５ V １．７５～１．８５ P ０．１５～０．２５ O ７ Cổ １．７５～１．８５ Zhn ０．１５～０．２５ V １．５５～１．６５ P ０．３５～０．４５ O ７ Cổ １．７５～１．８５ Zhn ０．１５～０．２５ V １．３５～１．４５ P ０．５５～０．６５ O ７ Cổ １．７５～１．８５ Zhn ０．１５～０．２５ V ０．９５～１．０５ P ０．９５～１．０５ O ７ Cổ １．７５～１．８５ Zhn ０．１５～０．２５ V ０．４５～０．５５ P １．４５～１．５５ O ７ Cổ １．７５～１．８５ Zhn ０．１５～０．２５ V ０．１５～０．２５ P １．７５～１．８５ O ７ Cổ １．７５～１．８５ Zhn ０．１５～０．２５ V ０～０．０５ P １．９５～２ O ７ Cổ １．８５～１．９５ Mẽ ０．０５～０．１５ V ２ O ７ Cổ １．７～１．８ Ca ０．０５～０．１５ Mẽ ０．１～０．２ V ２ O ７ Cổ １．７５～１．８５ Ca ０．１５～０．２５ V １．７５～１．８５ P ０．１５～０．２５ O ７ Cổ １．７５～１．８５ Ca ０．０５～０．１５ Mẽ ０．０５～０．１５ V ２ O ７ Cổ １．５５～１．６５ Ca ０．３５～０．４５ V ２ O ７ Cổ １．８５～１．９５ Sr ０．０５～０．１５ V ２ O ７

[0093] This disclosure includes the following embodiments: [Embodiment 1-1] A method for manufacturing a negative thermal expansion material, comprising the step of adjusting the firing temperature when manufacturing a negative thermal expansion material represented by general formula (1), and adjusting at least one of the volume frequency center particle size and volume frequency 90% particle size of the negative thermal expansion material. [Embodiment 1-2] The method according to Embodiment 1-1, wherein the brightness on a grayscale of the negative thermal expansion material is adjusted. [Embodiment 1-3] The method according to Embodiment 1-2, wherein the brightness is adjusted to be smaller the higher the firing temperature and the higher the brightness. [Embodiment 1-4] The method according to Embodiment 1-2 or 1-3, wherein the brightness is adjusted to be smaller the lower the volume frequency center particle size or volume frequency 90% particle size and the higher the brightness. [Embodiment 1-5] The method according to Embodiment 1-2, wherein the brightness on a grayscale of the negative thermal expansion material is 0.7 or more and 1 or less, with black being 0 and white being 1. [Problems that Embodiment 1 aims to solve] When using a negative thermal expansion material as a thermal expansion inhibitor, the color of the negative thermal expansion material is also important. There is a need for a technology that provides a negative thermal expansion material with a color according to specifications. One of the purposes of this disclosure is to provide negative thermal expansion materials of various colors. [Effects of Embodiment 1] Providing negative thermal expansion materials of various colors can increase their practical value as materials. [Effect 2-1] A method for manufacturing a negative thermal expansion material, comprising the step of adjusting the color of the negative thermal expansion material by adjusting at least one of x1, x2, y1, y2, and z of the negative thermal expansion material represented by general formula (2). [Effect 2-2] The method according to Embodiment 2-1, wherein the hue of the negative thermal expansion material is adjusted between cyan and purple on the color wheel. [Effect 2-3] The method according to Embodiment 2-1 or 2-2, wherein A includes P, and increasing y2 adjusts the hue of the negative thermal expansion material counterclockwise on the color wheel. [Problems that Embodiment 2 aims to solve] When using a negative thermal expansion material as a thermal expansion inhibitor, the color of the negative thermal expansion material is also important. There is a need for technology to provide negative thermal expansion materials in colors according to specifications. One of the purposes of this disclosure is to provide negative thermal expansion materials of various colors. [Effects of Embodiment 2] By providing negative thermal expansion materials of various colors, the practical value of the material can be increased.[Aspect 3-1] A method for producing a composite material, comprising the step of forming a mixture of a powder containing a negative thermal expansion material and a resin into a sheet. [Aspect 3-2] The method according to aspect 3-1, wherein the mixture contains 10% by weight or more of the powder based on the total weight of the mixture. [Aspect 3-3] The method according to aspect 3-1, wherein the mixture contains 50% by weight or more of the powder based on the total weight of the mixture. [Aspect 3-4] The method according to aspect 3-1, wherein the mixture contains 80% by weight or more of the powder based on the total weight of the mixture. [Aspect 3-5] The method according to any one of aspects 3-1 to 3-4, wherein the negative thermal expansion material contains a compound represented by general formula (1). [Aspect 3-6] The method according to any one of aspects 3-1 to 3-4, wherein the negative thermal expansion material contains a compound represented by general formula (2). [Aspect 3-7] The method according to any one of aspects 3-1 to 3-4, wherein the negative thermal expansion material contains a compound represented by general formula (3). [Aspect 3-8] The composite material is the method according to any one of aspects 3-1 to 3-7, wherein the shape of the composite material changes when an electric field is applied. [Aspect 3-9] The composite material is the method according to any one of aspects 3-1 to 3-8, wherein the composite material is flexible. [Aspect 3-10] The composite material is the method according to any one of aspects 3-1 to 3-8, wherein the composite material is not flexible. [Aspect 3-11] A composite material comprising a resin and a negative thermal expansion material, having a sheet-like shape, wherein the powder of the negative thermal expansion material is dispersed in the resin. [Aspect 3-12] The composite material according to aspect 3-11, comprising 10% by weight or more of the negative thermal expansion material based on the total weight of the negative thermal expansion material and the resin. [Aspect 3-13] The composite material according to aspect 3-11, comprising 50% by weight or more of the negative thermal expansion material based on the total weight of the negative thermal expansion material and the resin. [Aspect 3-14] A composite material according to aspect 3-11, comprising 80% by weight or more of the negative thermal expansion material based on the total weight of the negative thermal expansion material and the resin. [Aspect 3-15] A composite material according to any one of aspects 3-11 to 3-14, wherein the negative thermal expansion material comprises a compound represented by general formula (1). [Aspect 3-16] A composite material according to any one of aspects 3-11 to 3-14, wherein the negative thermal expansion material comprises a compound represented by general formula (2).[Aspect 3-17] The negative thermal expansion material is a composite material according to any one of aspects 3-11 to 3-14, comprising a compound represented by general formula (3). [Aspect 3-18] A composite material according to any one of aspects 3-11 to 3-17, whose shape changes upon application of an electric field. [Aspect 3-19] A composite material according to any one of aspects 3-11 to 3-18, which is flexible. [Aspect 3-20] A composite material according to any one of aspects 3-11 to 3-18, which is not flexible. [Problems that Aspect 3 aims to solve] The present inventors have come up with a composite material that takes advantage of the characteristics of the negative thermal expansion material described above. One of the purposes of this disclosure is to provide a new composite material comprising a negative thermal expansion material. [Effects of Aspect 3] A composite material with high practical value can be provided. [Aspect 4-1] A composite material comprising a negative thermal expansion material comprising a compound represented by general formula (1), with a volume frequency of 90% particle size (D. ９０ A powder in which the particle size (D) is 50 μm or less. [Aspect 4-2] Volume frequency 50% particle size (D ５０ A powder according to embodiment 4-1, wherein the particle size is 20 μm or less. [Embodiment 4-3] A negative thermal expansion material comprising a compound represented by general formula (2), wherein the volume frequency 90% particle size (D ９０ Powder having a particle size of 50 μm or less. [Aspect 4-4] Volume frequency 50% particle size (D ５０ A powder according to embodiment 4-3, wherein the particle size (D) is 20 μm or less. [Embodiment 4-5] A powder containing a negative thermal expansion material, with a volume frequency of 90% particle size (D ９０) a powder having a particle size of 4 μm or less. [Aspect 4-6] The negative thermal expansion material is the powder according to aspect 4-5, comprising a compound represented by general formula (1). [Aspect 4-7] The negative thermal expansion material is the powder according to aspect 4-5, comprising a compound represented by general formula (2). [Aspect 4-8] The negative thermal expansion material is the powder according to any one of aspects 4-1 to 4-7, comprising a compound represented by general formula (3). [Problems that Aspect 4 aims to solve] The inventors recognized that in order to suppress negative thermal expansion in minute components in fields such as electronic devices, it is necessary not only for the average particle size of the negative thermal expansion material powder to be small, but also for there to be few coarse particles, and came up with the technology of this disclosure. One of the purposes of this disclosure is to provide a negative thermal expansion material powder having excellent properties. [Effects of Aspect 4] By providing a negative thermal expansion material having excellent properties, the practical value of the powder can be increased.

[0094] The present disclosure has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications are also within the scope of the present disclosure.

[0095] This disclosure is applicable to powders, methods for producing negative thermal expansion materials, methods for producing composite materials, and composite materials.

Claims

1. General formula (1) Zn ｘ１ T ｘ２ P ｙ１ A ｙ２ O ｚ (T is Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, L Selected from a, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho The material contains a negative thermal expansion material comprising a compound represented by ), which includes at least one element, where A is at least one element selected from Li, Ca, Sr, Ba, Al, Si, V, Ge, Sn, La, Ce, Y, Pr, Nd, Sm, and satisfies 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8, and has a volume frequency of 90% particle size (D ９０ A powder in which the diameter is 50 μm or less.

2. Volume frequency 50% particle size (D ５０ The powder according to claim 1, wherein the diameter is 20 μm or less.

3. General formula (2) Cu ｘ１ T ｘ２ V ｙ１ A ｙ２ O ｚ (T contains at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho; A contains at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, P, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, Y, Pr, Nd, Sm; 0 ≦ x2 < 2, 0 ≦ y2 ≦ 2, 1.7 ≦ x1 + x2 ≦ 2.3, 1.7 ≦ y1 + y2 ≦ 2.3, 6 ≦ z ≦ 8 are satisfied.) A negative thermal expansion material containing a compound represented by the formula, and a powder having a volume frequency 90% particle size (D ９０ ) of 50 μm or less.

4. Volume frequency 50% particle size (D ５０ The powder according to claim 3, wherein the diameter is 20 μm or less.

5. Contains negative thermal expansion material, volume frequency 90% particle size (D ９０ A powder in which the diameter is 4 μm or less.

6. The negative thermal expansion material is Zn, according to general formula (1). ｘ１ T ｘ２ P ｙ１ A ｙ２ O ｚ (T is Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La , Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho The powder according to claim 5, comprising a compound represented by 0≦x²<2, 0≦y²≦2, 1.7≦x¹+x²≦2.3, 1.7≦y¹+y²≦2.3, and 6≦z≦8.

7. The negative thermal expansion material is Cu according to general formula (2) ｘ１ T ｘ２ V ｙ１ A ｙ２ O ｚ (T includes at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, and A includes Li, Mg, Ca, S The powder according to claim 5, comprising a compound represented by r, Ba, Al, Si, P, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, Y, Pr, Nd, Sm, and satisfying 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8.

8. The negative thermal expansion material is the general formula (3) Ti ｘ１ M ｘ２ O ３ A powder according to any one of claims 1 to 7, comprising a compound represented by (M, which comprises at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, and satisfies 0 ≤ x² < 2 and 1.7 ≤ x¹ + x² ≤ 2.3).

9. General formula (1) Zn ｘ１ T ｘ２ P ｙ１ A ｙ２ O ｚ (T is Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Contains at least one element selected from Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, A is Li, Ca, Sr, Ba, Al, Si, V, Ge, Sn, A method for producing a negative thermal expansion material, comprising the steps of: adjusting the firing temperature when producing a negative thermal expansion material represented by (containing at least one element selected from La, Ce, Y, Pr, Nd, and Sm, and satisfying 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8); and adjusting the color of the negative thermal expansion material by adjusting at least one of the volume frequency center particle size and the volume frequency 90% particle size of the negative thermal expansion material.

10. The method according to claim 9, wherein the brightness of the negative thermal expansion material in grayscale is adjusted.

11. The method according to claim 10, wherein the brightness is adjusted to be lower as the firing temperature increases and the brightness increases.

12. The method according to claim 10 or 11, wherein the brightness is adjusted to be smaller as the volume frequency center particle size or volume frequency 90% particle size decreases and the brightness increases.

13. The method according to claim 10, wherein the luminance of the negative thermal expansion material on a grayscale is 0.7 or more and 1 or less, with black being 0 and white being 1.

14. General formula (2) Cu ｘ１ T ｘ２ V ｙ１ A ｙ２ O ｚ (T includes at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, and A includes Li, Mg, Ca, Sr, Ba, Al, Si, P, Ti, Cr, Mn, Fe, Co, Ni A method for producing a negative thermal expansion material, comprising the step of adjusting the color of a negative thermal expansion material represented by a negative thermal expansion material (containing at least one element selected from Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, Y, Pr, Nd, Sm, and satisfying 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8).

15. The method according to claim 14, wherein the hue of the negative thermal expansion material is adjusted to be between cyan and violet on the color wheel.

16. The method according to claim 14 or 15, wherein A includes P, and increasing y2 adjusts the hue of the negative thermal expansion material counterclockwise on the hue wheel.

17. A method for manufacturing a composite material, comprising the step of forming a sheet-like mixture of a powder containing a negative thermal expansion material and a resin.

18. The method according to claim 17, wherein the mixture comprises 10% by weight or more of the powder based on the total weight of the mixture.

19. The method according to claim 17, wherein the mixture comprises 50% by weight or more of the powder based on the total weight of the mixture.

20. The method according to claim 17, wherein the mixture comprises 80% by weight or more of the powder based on the total weight of the mixture.

21. The negative thermal expansion material is Zn, according to general formula (1). ｘ１ T ｘ２ P ｙ１ A ｙ２ O ｚ (T is Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce , Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho. The method according to any one of claims 17 to 20, comprising a compound represented by ( ), wherein A comprises at least one element selected from Li, Ca, Sr, Ba, Al, Si, V, Ge, Sn, La, Ce, Y, Pr, Nd, Sm, and satisfies 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8.

22. The negative thermal expansion material is Cu according to general formula (2). ｘ１ T ｘ２ V ｙ１ A ｙ２ O ｚ (T includes at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, and A includes Li, Mg, Ca, Sr, Ba, A The method according to any one of claims 17 to 20, comprising a compound represented by (i, Si, P, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, Y, Pr, Nd, Sm, satisfying 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, 6 ≤ z ≤ 8).

23. The negative thermal expansion material is the general formula (3) Ti ｘ１ M ｘ２ O ３ The method according to any one of claims 17 to 20, comprising a compound represented by (M comprising at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, and satisfying 0 ≤ x² < 2 and 1.7 ≤ x¹ + x² ≤ 2.3).

24. The method according to any one of claims 17 to 20, wherein the composite material changes shape upon application of an electric field.

25. The method according to any one of claims 17 to 20, wherein the composite material is flexible.

26. The method according to any one of claims 17 to 20, wherein the composite material is not flexible.

27. A composite material comprising a resin and a negative thermal expansion material, having a sheet-like shape, wherein the powder of the negative thermal expansion material is dispersed within the resin.

28. The composite material according to claim 27, comprising 10% by weight or more of the negative thermal expansion material based on the total weight of the negative thermal expansion material and the resin.

29. The composite material according to claim 27, comprising 50% by weight or more of the negative thermal expansion material based on the total weight of the negative thermal expansion material and the resin.

30. The composite material according to claim 27, comprising 80% by weight or more of the negative thermal expansion material based on the total weight of the negative thermal expansion material and the resin.

31. The negative thermal expansion material is Zn, according to general formula (1). ｘ１ T ｘ２ P ｙ１ A ｙ２ O ｚ (T is Li, Mg, Al, Si, Ca, Sr, Ba, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce , Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho. A composite material according to any one of claims 27 to 30, comprising a compound represented by ), wherein A comprises at least one element selected from Li, Ca, Sr, Ba, Al, Si, V, Ge, Sn, La, Ce, Y, Pr, Nd, Sm, and satisfies 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8.

32. The negative thermal expansion material is Cu according to general formula (2) ｘ１ T ｘ２ V ｙ１ A ｙ２ O ｚ (T includes at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, B, Na, K, F, Cl, Br, I, Hf, Y, Yb, S, Mo, Te, Pb, Cd, Te, Nd, Sm, Eu, Tb, Dy, Ho, and A includes Li, Mg, Ca, Sr, Ba, Al A composite material according to any one of claims 27 to 30, comprising a compound represented by ) containing at least one element selected from Si, P, Ti, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, Y, Pr, Nd, Sm, and satisfying 0 ≤ x² < 2, 0 ≤ y² ≤ 2, 1.7 ≤ x¹ + x² ≤ 2.3, 1.7 ≤ y¹ + y² ≤ 2.3, and 6 ≤ z ≤ 8.

33. The negative thermal expansion material is the general formula (3) Ti ｘ１ M ｘ２ O ３ A composite material according to any one of claims 27 to 30, comprising a compound represented by (M, which comprises at least one element selected from Li, Mg, Ca, Sr, Ba, Al, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ce, Ta, W, Bi, and satisfies 0 ≤ x² < 2 and 1.7 ≤ x¹ + x² ≤ 2.3).

34. A composite material according to any one of claims 27 to 30, wherein the shape changes upon application of an electric field.

35. A composite material according to any one of claims 27 to 30, having flexibility.

36. A composite material according to any one of claims 27 to 30 that does not have flexibility.

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