Negative thermal expansion materials

Abstract

To provide a new material exhibiting negative thermal expansion.SOLUTION: A negative thermal expansion material comprises an oxide represented by general formula (1) Cu2-xRxV2-yPyO7 (wherein R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, and Sn, and satisfies 0<x<2 and 0<y<2), exhibits negative thermal expansion in a temperature range of 100 to 500 K, and has a linear expansion coefficient of -10 ppm / K or less at 400 K.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This application is based on Japanese Patent Application No. 2020-198758 filed on 30 November 2020 and Japanese Patent Application No. 2021-113729 filed on 8 July 2021, claiming the benefit of priority thereunder, and all the contents of those patent applications are incorporated herein by reference.

[0002] This disclosure relates to negative thermal expansion materials and components. [Background technology]

[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. -5 Even a small rate of change, such as a small one 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 have a significant impact on 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, negative thermal expansion materials are also known, 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 V2O7 is known (see Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-210198 [Overview of the project] [Problems that the invention aims to solve]

[0006] The above negative thermal expansion material has room for further improvement not only in terms of its properties but also in terms of the cost of the materials contained therein and the availability of the materials.

[0007] The present disclosure has been made in view of such circumstances, and one of its objectives is to provide a new material exhibiting negative thermal expansion.

Means for Solving the Problems

[0008] In order to solve the above problems, the negative thermal expansion material according to an aspect of the present disclosure contains an oxide represented by the general formula (1) Cu 2-x R x V 2-y P y O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 < x < 2 and 0 < y < 2), exhibits negative thermal expansion in the temperature range of 100 to 500 K, and has a linear expansion coefficient at 400 K of -10 ppm / K or less.

Advantages of the Invention

[0009] According to the present disclosure, a new material exhibiting negative thermal expansion can be provided.

Brief Description of the Drawings

[0010] [Figure 1] It is a diagram showing the X-ray diffraction patterns of β-Cu2P2O7 and β-Cu2V2O7, and Cu1.8Zn0.2V2-yPyO7 (y = 0.1, 0.2, 0.4, 0.6, 1.0, 2.0). [Figure 2] It is a diagram showing the X-ray diffraction patterns of β-Cu2P2O7 and β-Cu2V2O7, and Cu1.8Zn0.2V2-yPyO7 (y = 1.5, 1.8). [Figure 3] It is a diagram showing the thermal expansion characteristics of Cu1.8Zn0.2V2-yPyO7. [Figure 4] It is a diagram showing the thermal expansion characteristics of Cu1.5Zn0.5V1.4P0.6O7. [Figure 5] This figure shows the thermal expansion characteristics of Cu2V2-yPyO7 (x=0.2, 0.6). [Figure 6] This figure shows the X-ray diffraction pattern of Cu1.8Zn0.2V1.8P0.2O7 (line L9) fabricated by the spray-drying method. [Figure 7] This figure shows the thermal expansion characteristics of the composite material according to the embodiment. [Figure 8] This figure shows the thermal expansion characteristics of the composite material according to the embodiment. [Figure 9] This figure shows the X-ray diffraction pattern of Zn2-xMgxP2O7. [Figure 10] This figure shows the X-ray diffraction pattern of Zn2P2-yAyO7 (where A is one of Sn, Ge, Si, or V). [Figure 11] This figure shows the thermal expansion characteristics of Zn2-xMgxP2O7 (x=0, 0.2, 0.4, 0.6, 0.8, 2). [Figure 12] This figure shows the thermal expansion characteristics of Zn1.64Mg0.3Al0.06P2O7. [Figure 13] This figure shows the thermal expansion characteristics of Zn2P2-yAyO7 (x=0.1, A is either Sn or Si). [Figure 14] This figure shows the X-ray diffraction pattern of Ti2-xMxO3 (where M is one of Mn, Cr, V, Si, Ta, Nb, and Zr). [Figure 15] This figure shows the thermal expansion properties of Ti2-xMxO3 (where M is either Cr or Nb). [Figure 16] This figure shows the thermal expansion properties of Ti2-xMxO3 (where M is either Si or Al). [Figure 17] This is a diagram showing the colors of Cu1.8Zn0.2V2-yPyO7. [Modes for carrying out the invention]

[0011] The inventors of the present invention have focused on the Cu2V2O7 system as a candidate for materials that exhibit negative thermal expansion. α-Cu2V2O7, which has a cubic crystal structure, has attracted attention as a multiferroic material in which strong ferroelectricity and weak paramagnetism coexist. However, in a relatively wide temperature range above room temperature, including room temperature, anisotropic thermal deformation of the crystal lattice, which is thought to be caused by dielectric instability, is observed. As a result, negative thermal expansion appears, in which the unit cell volume shrinks as the temperature rises over a wide temperature range.

[0012] By substituting various elements for Cu2V2O7, it can take on a monoclinic β-phase and a triclinic γ-phase in addition to the cubic α-phase. Therefore, the inventors of the present invention have found that when a part of the Cu site or V site is substituted with another element, negative thermal expansion characteristics that cannot be realized in the conventional α-Cu2V2O7 system are exhibited, and have devised the negative thermal expansion materials exemplified below.

[0013] In addition, the inventors of the present invention have focused on the Zn2P2O7 system as a further candidate for materials that exhibit negative thermal expansion. Zn2P2O7 has a stable α-phase of monoclinic I2 / c at low temperatures and a β-phase of monoclinic C2 / m at high temperatures, and exhibits a transition accompanied by a large contraction of about 1.68% (calculated value from lattice constants) at about 405K as the temperature rises. The inventors of the present invention have found that when a part of the Zn site or P site is substituted with another element, negative thermal expansion characteristics are exhibited, and have devised the negative thermal expansion materials exemplified below.

[0014] In addition, the inventors of the present invention have focused on the Ti₂O₃ system as a further candidate for materials that exhibit negative thermal expansion. Corundum-type Ti₂O₃ is stable at room temperature and normal pressure, has a hexagonal crystal structure of R-3c (the "-" is above the 3), and is composed of a stack of honeycomb lattices. Ti₂O₃ is also a Mott-Hubbard-type insulator that exhibits a metal-insulator transition at 400 to 600K, and the unit cell exhibits anisotropic positive thermal expansion during the transition. The inventors of the present invention have found that when a part of the Ti site is substituted with another element, negative thermal expansion characteristics are exhibited, and have devised the negative thermal expansion materials exemplified below. [[ID=]]

[0015] The negative thermal expansion material according to an aspect of the present disclosure has the general formula (1) Cu 2-x R x V2-y P y It contains an oxide represented by O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2).

[0016] According to this aspect, by substituting relatively expensive V with relatively inexpensive P, a new and less expensive negative thermal expansion material can be provided while maintaining the characteristics of negative thermal expansion to a certain extent.

[0017] The oxide may have a linear expansion coefficient of -10 ppm / K or less at 400 K.

[0018] In the general formula (1), x may be 0.1 to 1.6. More preferably, x is 0.1 to 1.0. Thereby, a negative linear expansion coefficient with an absolute value larger than that of α-Cu2V2O7 in which Cu is not substituted by R can be realized.

[0019] In the general formula (1), y may be 0.1 to 1.8. More preferably, y is 0.1 to 1.2. Thereby, a negative thermal expansion material less expensive than Cu 2-x R x V2O7 can be provided.

[0020] The oxide may contain a monoclinic β phase.

[0021] It may contain at least one of an oxide with a monoclinic crystal system and an oxide with an orthorhombic crystal system. Also, the oxide may have a crystal structure selected from any of the space groups C2 / c, C2 / m, Fdd2.

[0022] The negative thermal expansion material may exhibit negative thermal expansion in the temperature range of 100 to 500 K.

[0023] The negative thermal expansion material may have a linear expansion coefficient of -10 ppm / K or less in the temperature range of 100 to 500 K.

[0024] The negative thermal expansion material may change color by changing y in the general formula (1). According to this aspect, it can be used for thermal expansion control of paints and the like.

[0025] The negative thermal expansion material of another aspect of the present disclosure is represented by the general formula (2) Zn 2-x T x P 2-y A y O7 (T contains at least one element selected from Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and A contains at least one element selected from Al, Si, V, Ge, Sn, and 0 ≤ x < 2, 0 ≤ y ≤ 2 are satisfied. However, (x, y) = (0, 0) and (0, 2) are excluded.) and contains an oxide represented by.

[0026] According to this aspect, a new inexpensive negative thermal expansion material with large negative thermal expansion near room temperature can be provided.

[0027] In the general formula (2), the oxide where x = 0, 0 < y < 2, and A = V may be excluded.

[0028] In the general formula (2), x may be 0.1 to 1.6.

[0029] In the general formula (2), y may be 0.1 to 1.6.

[0030] The negative thermal expansion material may exhibit negative thermal expansion in the temperature range of 200 to 400K.

[0031] The negative thermal expansion material may have a linear expansion coefficient of -10 ppm / K or less in the temperature range of 200 to 400K.

[0032] The negative thermal expansion material of still another aspect of the present disclosure is represented by the general formula (3) Ti 2-x M xIt contains an oxide represented by O3 (M contains at least one element selected from Mg, Al, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and satisfies 0 ≦ x < 2).

[0033] According to this aspect, an inexpensive new negative thermal expansion material can be provided.

[0034] In the general formula (3), x may satisfy 0 < x ≦ 1.6. More preferably, x is 0.05 to 1.6, and even more preferably, 0.1 to 1.0.

[0035] The negative thermal expansion material may exhibit negative thermal expansion in the temperature range of 100 to 500 K.

[0036] The negative thermal expansion material may have a linear expansion coefficient of -10 ppm / K or less in the temperature range of 100 to 500 K.

[0037] Still another aspect of the present disclosure is a composite material. This composite material includes a negative thermal expansion material and a positive thermal expansion material having a positive linear expansion coefficient. Thereby, a composite material with suppressed volume change against temperature change can be realized.

[0038] Still another aspect of the present disclosure is a method for manufacturing a negative thermal expansion material. This manufacturing method includes a step of preparing an aqueous solution containing a raw material of a compound represented by the general formula (1) Cu 2-x R x V 2-y P y O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2).) and an organic acid.

[0039] Still another aspect of the present disclosure is also a method for manufacturing a negative thermal expansion material. This manufacturing method includes the general formula (2) Zn 2-x T x P 2-y A yThe process includes preparing an aqueous solution containing the raw materials for a compound represented by O7 (where T is at least one element selected from Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and A is at least one element selected from Al, Si, V, Ge, Sn, satisfying 0≦x<2 and 0≦y≦2, excluding (x,y)=(0,0) and (0,2)), and an organic acid.

[0040] Another aspect of this disclosure is a component, which comprises a negative thermal expansion material, or a composite material comprising a negative thermal expansion material and a positive thermal expansion material having a positive linear expansion coefficient. This enables the realization of a component in which volume changes with respect to temperature changes are suppressed.

[0041] The following describes in detail the forms for implementing this disclosure, with reference to drawings and other materials.

[0042] [First Embodiment] Using solid-phase reaction methods, Cu 2-x R x V 2-y P y A polycrystalline sintered body (ceramic) sample of O7 (R is Zn) was prepared. Specifically, CuO, ZnO, V2O3 or V2O5, and (NH4)2HPO4 or (NH4)H2PO4, weighed in stoichiometric ratios, were mixed in air for 1 hour using an agate mortar and pestle. Next, the mixed powder was pressed into pellets and heated in air at a temperature of 873-953K for 10 hours. The resulting powder was sintered using a spark plasma sintering (SPS) furnace (manufactured by SPS Syntex Co., Ltd.) to obtain an oxide sintered body. Sintering was carried out under vacuum (<10°C). -1 The process was carried out at 723K for 5 minutes under Pa) using a graphite die. Note that the starting materials are not limited to those listed above; P2O5, Zn2P2O7, Cu2P2O7, etc., can also be used. Furthermore, the sintered body is obtained by sintering the raw materials, and can take any form, such as powder or powder aggregated and processed into a predetermined shape.

[0043] Subsequently, the crystal structure of each sample was evaluated using powder X-ray diffraction (XRD) (measurement temperature 295K, characteristic X-ray of CuKα: wavelength λ=0.15418nm) and synchrotron temperature-dependent X-ray diffraction (wavelength λ=0.06521nm). Figure 1 shows β-Cu2P2O7 and β-Cu2V2O7, and Cu 1.8 Zn 0.2 V 2-y P y This figure shows the X-ray diffraction patterns of O7 (y=0.1, 0.2, 0.4, 0.6, 1.0, 2.0). Figure 2 shows the X-ray diffraction patterns of β-Cu2P2O7 and β-Cu2V2O7, and Cu 1.8 Zn 0.2 V 2-y P y This figure shows the X-ray diffraction patterns of O7 (y=1.8, 1.5). Note that the X-ray diffraction patterns of β-Cu2P2O7 and β-Cu2V2O7 are calculated values.

[0044] As shown in Figures 1 and 2, β-Cu2P2O7 (line L1) is an oxide sintered body corresponding to the high-temperature phase and has a monoclinic crystal structure with a space group of C2 / m. On the other hand, β-Cu2V2O7 (line L8) is also an oxide sintered body corresponding to the high-temperature phase, but has a monoclinic crystal structure with a space group of C2 / c. It should be noted that any of these oxide sintered bodies may have a crystal structure with a space group of C2 / c, C2 / m, or Fdd2 by substituting some elements or manufacturing them using different methods.

[0045] Furthermore, as shown in Figures 1 and 2, Cu is partially replaced with Zn. 1.8 Zn 0.2 V 2-y P y O7 (lines L2 to L7, L9, L10) also has a β phase (monoclinic) crystal structure. In other words, general formula (1) Cu 2-x R x V 2-y P yIn O7, by including an element that substitutes for Cu in R and substituting part of V with P, it is inferred that the β phase, which does not exist stably except at high temperatures (above 977K) in the Cu2V2O7 composition, can exist stably over a wide temperature range including room temperature. It should be noted that the negative thermal expansion material according to this embodiment is not necessarily limited to cases where the contained oxide is monoclinic, and may contain at least one of an oxide with a monoclinic crystal system and an oxide with an orthorhombic crystal system.

[0046] Figure 3 shows β-Cu 1.8 Zn 0.2 V 2-y P y This figure shows the thermal expansion characteristics of O7. The vertical axis represents the length change ΔL / L relative to the length L at 100K. The length change is calculated using the linear expansion coefficient α obtained with a laser thermal expander (LIX-2: manufactured by ULVAC, Inc.) (measurement temperature range 100~500K).

[0047] As shown in Figure 3, β-Cu 1.8 Zn 0.2 V 2-y P y When the ratio y of P substituted for V in O7 is 0.1, 0.4, or 0.6, negative thermal expansion is observed in the temperature range of 100 to 500 K, and the coefficient of linear expansion at 400 K is -10 ppm / K or less. In particular, when the value of y is 0.1 or 0.4, the coefficient of linear expansion is -10 ppm / K or less in the temperature range of 100 to 500 K, indicating large negative thermal expansion over a wide temperature range, including room temperature.

[0048] In this embodiment, Zn is used as an example of a substitution element for Cu, but it is presumed that negative thermal expansion will also be observed when a portion of Cu is substituted with elements such as Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, and Sn.

[0049] Next, we will explain the effect of the proportion of Zn used to substitute for Cu. Figure 4 shows Cu 1.5 Zn 0.5 V 1.4 P 0.6It is a diagram showing the thermal expansion characteristics of O7. As shown in Fig. 4, even when the ratio x of Zn substituting Cu is 0.5, it shows negative thermal expansion in the temperature range of 100 to 500 K, and the linear expansion coefficient at least at 400 K is -10 ppm / K or less. Note that the ratio x of the element R substituting Cu may be 0.1 to 1.6. More preferably, x is 0.1 to 1.0. Thereby, a negative linear expansion coefficient having an absolute value larger than that of α-Cu2V2O7 in which Cu is not substituted with the element R can be realized.

[0050] Fig. 5 is of Cu2V 1.8 P 0.2 O7 and Cu2V 1.4 P 0.6 It is a diagram showing the thermal expansion characteristics of O7. As shown in Fig. 5, even when Cu is not substituted and V is substituted with P. It shows negative thermal expansion in the temperature range of 100 to 500 K, and the linear expansion coefficient at least at 400 K is -10 ppm / K or less.

[0051] As described above, the negative thermal expansion material according to the present embodiment has the general formula (1) Cu 2-x R x V 2-y P y O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2.) is an oxide sintered body represented by this. Thereby, by substituting relatively expensive V with relatively inexpensive P, it is possible to provide a new and less expensive negative thermal expansion material while maintaining the characteristics of negative thermal expansion to some extent. Also, y in the general formula (1) may be 0.1 to 1.8. More preferably, y is 0.1 to 1.2. Thereby, it is possible to provide a negative thermal expansion material that is less expensive than Cu 2-x R x R V2O7.

[0052] [Second Embodiment] Using the spray drying method, β-Cu 1.8 Zn 0.2 V 2-y P yA polycrystalline sintered body (ceramics) sample of O7 was prepared. Specifically, Cu obtained by the solid-state reaction method 2-x Zn x V 2-y P y For 1 g of the sample powder of O7, 3 g of anhydrous citric acid and about 100 ml of pure water are added, and it is stirred using a magnetic stirrer until all the sample powder dissolves.

[0053] Then, the obtained aqueous solution is spray-dried using a spray dryer (Yamato Scientific ADL-311SA) under the conditions of a spray rate of 2 ml / min and a temperature of 150 °C to obtain a citrate powder. This powder is put into an alumina crucible and heated in the air at 673 K for 5 to 10 hours to decompose citric acid. The obtained product is thoroughly crushed in a mortar, molded into pellets, put into an alumina crucible, and fired in the air at 873 to 953 K for 2 to 10 hours using an electric furnace.

[0054] Organic acids such as acetic acid may be used instead of the aforementioned citric acid. Also, after mixing the raw materials in a molar ratio, they may be directly mixed with citric acid to form an aqueous solution. Note that the concentration of the citric acid aqueous solution, the conditions of spray drying, etc. are not limited to those described above. Also, the decomposition process of citric acid and the chemical reaction process may be carried out continuously. Also, the process from spray drying to the final chemical reaction may be carried out in a continuous process.

[0055] Figure 6 is a diagram showing the X-ray diffraction pattern of Cu 1.8 Zn 0.2 V 1.8 P 0.2 O7 (line L11) prepared by the spray drying method. From the pattern shown by line L11, it can be seen that Cu 1.8 Zn 0.2 V 1.8 P 0.2 O7 (line L6) has the same crystal structure.

[0056] Thus, β-Cu 1.8 Zn 0.2 V 1.8 P 0.2O7 can obtain a linear expansion coefficient as large as that of β-Cu manufactured by the solid-phase reaction method by optimizing the firing conditions. 1.8 Zn 0.2 V 1.8 P 0.2 O7, and can also obtain a linear expansion coefficient equal to or greater than that of at least the conventionally known α-Cu2V2O7.

[0057] As described above, the method for manufacturing a negative thermal expansion material by the spray drying method includes a step of preparing an aqueous solution containing a raw material of a compound represented by the general formula (1) Cu 2-x R x V 2-y P y O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2). According to this manufacturing method, a negative thermal expansion material having a negative linear expansion coefficient with an absolute value larger than that of α-Cu2V2O7 in which Cu is not substituted with Zn can be manufactured relatively inexpensively by using an aqueous solution that is easy to handle at low temperatures. In addition, since a part of V can be substituted with P, a more inexpensive negative thermal expansion material can be provided.

[0058] In addition, the above manufacturing method includes a step of drying and granulating the aqueous solution by the spray drying method to produce a powder of an organic acid salt. Thereby, a powder of an organic acid salt can be manufactured without requiring excessive energy such as granulation and pulverization at high temperatures or expensive equipment.

[0059] In addition, the above manufacturing method includes a step of heating the powder of the organic acid salt to decompose the organic acid, and a step of firing the powder from which the organic acid has been decomposed to produce an oxide sintered body. Thereby, an oxide sintered body having a desired shape can be produced with relatively low energy.

[0060] As described above, the negative thermal expansion material manufactured by the manufacturing method according to the embodiment of the present disclosure has a substantially constant linear expansion coefficient with respect to temperature change in a wide temperature range up to about 100 to 500 K, and material function design is easy. In addition, it is mainly composed of inexpensive elements such as Cu, Zn, and P, has a low synthesis temperature with oxides, is easy to manufacture, and has industrial advantages such as being able to obtain fine particles.

[0061] [Third Embodiment] General formula (1) Cu 2-x R x V 2-y P y A composite material containing a negative thermal expansion material represented by O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2) and a positive thermal expansion material having a positive linear expansion coefficient such as resin or metal will be described.

[0062] FIG. 7 is a diagram showing the thermal expansion characteristics of the composite material according to the present embodiment. The composite material shown in FIG. 7 is a mixture of 30 vol% of Cu 1.8 Zn 0.2 V 1.6 P 0.4 O7 having a linear expansion coefficient α of -10 ppm / K or more and 70 vol% of an epoxy resin having a linear expansion coefficient α of 60 ppm / K. As shown in FIG. 7, the composite material according to the present embodiment greatly suppresses thermal expansion (volume change) with respect to temperature change compared to the case of epoxy resin alone. Instead of epoxy resin, it may contain resin materials such as engineering plastics, polyvinyl butyral resin, phenolic resin, or metal materials such as aluminum.

[0063] FIG. 8 is also a diagram showing the thermal expansion characteristics of the composite material according to the present embodiment. One of the three composite materials shown in FIG. 8 is the composite material shown in FIG. 7. Another one is Cu 1.8 Zn 0.2 V 1.0 P 1.0It is a mixture of 30 vol% oxygen and 70 vol% epoxy resin with a coefficient of thermal expansion α of 60 ppm / K. The remaining one is Cu 1.8 Zn 0.2 This material is a mixture of 30 vol% VO and 70 vol% epoxy resin with a coefficient of linear expansion α of 60 ppm / K. The composite material according to this embodiment, shown in Figure 8, also exhibits significantly suppressed thermal expansion (volume change) in response to temperature changes compared to the epoxy resin alone.

[0064] [Fourth Embodiment] Using a solid-phase reaction method, Zn 2-x T x Polycrystalline sintered (ceramic) samples of P2O7 (T is Mg) were prepared. Specifically, ZnO, MgO, and (NH4)2HPO4 or (NH4)H2PO4, weighed in stoichiometric ratios, were mixed in air for 1 hour using an agate mortar and pestle. Next, the mixed powder was pressed into pellets and heated in air at a temperature of 1023-1173K for 2-10 hours. If the sinterability was insufficient, the obtained sample was crushed into powder in air using an agate mortar and pestle, and the above firing process was repeated, or sintered using a spark plasma sintering (SPS) furnace (manufactured by SPS Syntex Co., Ltd.). SPS sintering is performed in a vacuum (<10°C). -1 The process was carried out at 823-1023K for 5 minutes under Pa (pressure). Note that the starting materials are not limited to those listed above; P2O5, Zn2P2O7, Mg2P2O7, etc., can also be used. When substituting part of P with T (e.g., V), T powder or T oxides such as V2O5 can be used as starting materials.

[0065] Subsequently, the crystal structure of each sample was evaluated using powder X-ray diffraction (XRD) (measurement temperature 295K, characteristic X-ray of CuKα: wavelength λ=0.15418nm) and synchrotron temperature-dependent X-ray diffraction (wavelength λ=0.06521nm). Figure 9 shows Zn 2-x Mg x This figure shows the X-ray diffraction pattern of P2O7. Figure 10 shows the X-ray diffraction pattern of Zn2P 2-y A y This figure shows the X-ray diffraction pattern of O7 (where A is one of Sn, Ge, Si, or V).

[0066] As shown in Figure 9, Zn 2-x T x It has been confirmed that P2O7 (T is Mg) can be obtained as a single-phase sample in all composition ranges from x = 0 to 2. At room temperature, the crystal structure has space group I2 / c for x = 0, 0.2, 0.4, and 0.6, space group C2 / m for x = 0.8 and 1.2, and space group B21 / c for x = 1.6 and 2.

[0067] As shown in Figure 10, Zn2P 2-y A y O7 (where A is one of Sn, Ge, Si, or V) shows that its main component has the same space group crystal structure as Zn2P2O7, indicating that A can take on various elements.

[0068] Figure 11 shows Zn 2-x Mg x This figure shows the thermal expansion characteristics of P2O7 (x=0, 0.2, 0.4, 0.6, 0.8, 2). Figure 12 shows Zn 1.64 Mg 0.3 Al 0.06 This figure shows the thermal expansion characteristics of P2O7. Figure 13 shows Zn2P 2-y A y This figure shows the thermal expansion characteristics of O7 (x=0.1, A is either Sn or Si). In all three figures, from 11 to 13, the vertical axis represents the change in length ΔL / L relative to the length L at 100K. The change in length is calculated using the linear expansion coefficient α obtained with a laser thermal expander (LIX-2: manufactured by ULVAC, Inc.) (measurement temperature range 100~500K).

[0069] As shown in Figure 11, Zn 2-x Mg x When the ratio x of Mg substituting Zn in P2O7 is 0.2, 0.4, 0.6, or 0.8, negative thermal expansion is observed in the temperature range of 200-400K. In particular, when x is 0.6 or 0.8, large negative thermal expansion is observed over a wide temperature range, including room temperature.

[0070] In this embodiment, Mg is used as an example of a substitution element for Zn, but it is presumed that negative thermal expansion will also be observed when a portion of Zn is substituted with elements such as Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, and Bi. For example, Zn with a portion of it substituted with Mg and Al. 1.64 Mg 0.3 Al 0.06 P2O7 also exhibits negative thermal expansion, as shown in Figure 12.

[0071] As shown in Figure 13, Zn2P 2-y A y O7 (where A is either Sn or Si) exhibits negative thermal expansion around 400K.

[0072] As described above, the negative thermal expansion material according to this embodiment is Zn (2) 2-x T x P 2-y A y This is an oxide sintered body represented by O7(T contains at least one element selected from Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and A contains at least one element selected from Al, Si, V, Ge, Sn, satisfying 0≦x<2 and 0≦y≦2, except for (x,y)=(0,0) and (0,2).). This provides a new, inexpensive negative thermal expansion material with large negative thermal expansion near room temperature. Furthermore, x in general formula (2) may be between 0.1 and 1.6. More preferably, y is between 0.5 and 1.0. This provides an even cheaper negative thermal expansion material.

[0073] [Fifth Embodiment] In the same manner as in the second embodiment, Zn can also be produced by spray drying. 2-x T x A polycrystalline sintered body (ceramic) sample of P2O7 (T is Mg) was prepared. That is, the method for producing a negative thermal expansion material according to this embodiment is based on the general formula (2) Zn 2-x T x P 2-yA y The method includes a step of preparing an aqueous solution containing the raw materials for a compound represented by O7 (where T is at least one element selected from Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and A is at least one element selected from Al, Si, V, Ge, Sn, satisfying 0≦x<2 and 0≦y≦2, excluding (x,y)=(0,0) and (0,2)). This manufacturing method allows for the relatively inexpensive production of a negative thermal expansion material having a large absolute negative coefficient of linear expansion by utilizing the form of an aqueous solution that is easy to handle at low temperatures.

[0074] [Sixth Embodiment] Ti 2-x M x Polycrystalline sintered (ceramic) samples of O3 (where M is one of Al, Mn, Cr, V, Si, Ta, Nb, and Zr) were prepared. Specifically, powders of TiO2, Ti, and M, weighed in stoichiometric ratios, were mixed for 1 hour in air or in a glove box using an agate mortar and pestle. Next, the mixed powder was pressed into pellets and placed in a vacuum-sealed quartz tube (<10°C). -3 The sample was heated at a temperature of 1223-1323K for 20-50 hours. If the sinterability was insufficient, the obtained sample was crushed into powder using an agate mortar and pestle in air or in a glove box, and then sintered using a spark plasma sintering (SPS) furnace (manufactured by SPS Syntex Co., Ltd.). Sintering was carried out under vacuum (<10°C). -1 Under Pa (pressure), the process was carried out at 1173K for 2-5 minutes using a graphite die. Note that the starting material is not limited to the above; Cr2O3 and other materials can also be used.

[0075] Subsequently, the crystal structure of each sample was evaluated using powder X-ray diffraction (XRD) (measurement temperature 295K, characteristic X-ray of CuKα: wavelength λ=0.15418nm) and synchrotron temperature-dependent X-ray diffraction (wavelength λ=0.06521nm). Figure 14 shows the Ti 2-x M xThis figure shows the X-ray diffraction pattern of O3 (where M is one of Mn, Cr, V, Si, Ta, Nb, and Zr).

[0076] As shown in Figure 14, Ti 2-x M x O3 (where M is one of Mn, Cr, V, Si, Ta, Nb, and Zr) has been shown to have a crystal structure with the same space group as Ti2O3, indicating that M can take on various elements.

[0077] Figure 15 shows Ti 2-x M x This figure shows the thermal expansion properties of O3 (where M is either Cr or Nb). Figure 16 shows the properties of Ti 2-x M x This figure shows the thermal expansion characteristics of O3 (where M is either Si or Al). In both Figures 15 and 16, the vertical axis represents the length change ΔL / L relative to the length L at 300K. The length change is calculated using the linear expansion coefficient α obtained with a laser thermal expander (LIX-2: manufactured by ULVAC, Inc.) (measurement temperature range 100~700K).

[0078] As shown in Figures 15 and 16, Ti 2-x M x O3 (where M is one of Cr, Nb, Si, or Al) exhibits negative thermal expansion in the temperature range of 400-600K.

[0079] In this embodiment, Cr, Nb, Si, and Al are used as examples of substitution elements for Ti, but it is presumed that negative thermal expansion will also be observed when a portion of Ti is substituted with elements such as Mg, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Mo, Ag, In, Sn, Sb, La, Ta, W, and Bi.

[0080] As described above, the negative thermal expansion material according to this embodiment is based on the general formula (3)Ti 2-x M xIt is an oxide sintered body represented by O3 (M contains at least one element selected from Mg, Al, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and satisfies 0 ≦ x < 2). Thereby, an inexpensive new negative thermal expansion material can be provided.

[0081] [The Seventh Embodiment] General formula (1) Cu 2-x R x V 2-y P y The color of the negative thermal expansion material represented by O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2) will be described.

[0082] FIG. 17 is a diagram showing the color of Cu 1.8 Zn 0.2 V 2-y P y O7, which is a negative thermal expansion material. In the general formula (1), when R = Zn and x = 0.2, the negative thermal expansion material Cu 1.8 Zn 0.2 V 2-y P y O7 can change its color, such as reddish brown (y = 0), orange (y = 0.6), yellow (y = 1.0), yellowish green (y = 1.5), light green (y = 1.8), sky blue (y = 2.0), by changing y from 0 to 2.0. Since the solid solution ratio (y) of vanadium and phosphorus can be arbitrarily changed, a negative thermal expansion material of any color between the examples shown in this figure can be manufactured. Thus, the negative thermal expansion material represented by the general formula (1) Cu 2-x R x V 2-y P y O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2) can change its color by changing y, so it can be used for thermal expansion control of paints and the like.

[0083] As described above, the present disclosure has been described based on embodiments. It is understood by those skilled in the art that these embodiments are illustrative, and various modifications are possible for each component and combination of each processing process, and such modifications are also within the scope of the present disclosure.

[0084] Generalizing the invention embodied by the above embodiments leads to the following technical ideas.

[0085] (First Aspect) An oxide-containing negative thermal expansion material represented by the general formula (1): Cu 2-x R x V 2-y P y O7 (where R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2).

[0086] (Second Aspect) The negative thermal expansion material according to the first aspect, wherein the oxide has a linear expansion coefficient of -10 ppm / K or less at 400 K.

[0087] (Third Aspect) The negative thermal expansion material according to the first or second aspect, wherein x in the general formula (1) is 0.1 to 1.6.

[0088] (Fourth Aspect) The negative thermal expansion material according to any one of the first to third aspects, wherein y in the general formula (1) is 0.1 to 1.8.

[0089] (Fifth Aspect) The negative thermal expansion material according to any one of the first to fourth aspects, wherein the oxide contains a monoclinic β-phase.

[0090] (Sixth Aspect) The negative thermal expansion material according to any one of the first to fourth aspects, which contains at least one of an oxide having a monoclinic crystal system and an oxide having an orthorhombic crystal system.

[0091] (Seventh Aspect) The negative thermal expansion material according to the sixth aspect, wherein the oxide has a crystal structure selected from any of the space groups C2 / c, C2 / m, and Fdd2.

[0092] (8th Aspect) A negative thermal expansion material according to any one of the 1st to 7th aspects, characterized by exhibiting negative thermal expansion in the temperature range of 100 to 500 K.

[0093] (9th Aspect) A negative thermal expansion material according to any one of the 1st to 8th aspects, characterized by having a linear expansion coefficient of -10 ppm / K or less in the temperature range of 100 to 500 K.

[0094] (10th Aspect) A negative thermal expansion material containing an oxide represented by the general formula (2) Zn 2-x T x P 2-y A y O7 (T contains at least one element selected from Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and A contains at least one element selected from Al, Si, V, Ge, Sn, satisfying 0 ≦ x < 2, 0 ≦ y ≦ 2. However, (x, y) = (0, 0) and (0, 2) are excluded.)

[0095] (11th Aspect) A negative thermal expansion material according to the 10th aspect, characterized in that x in the general formula (2) satisfies 0 < x ≦ 1.6.

[0096] (12th Aspect) A negative thermal expansion material according to the 10th or 11th aspect, characterized in that y in the general formula (2) is 0.1 to 1.6.

[0097] (13th Aspect) A negative thermal expansion material according to any one of the 10th to 12th aspects, characterized by exhibiting negative thermal expansion in the temperature range of 200 to 400 K.

[0098] (14th Aspect) A negative thermal expansion material according to any one of the 10th to 13th aspects, characterized by having a linear expansion coefficient of -10 ppm / K or less in the temperature range of 200 to 400 K.

[0099] (15th Aspect) Ti according to the general formula (3) 2-x M xA negative thermal expansion material containing an oxide represented by O3 (M contains at least one element selected from Mg, Al, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and satisfies 0 ≦ x < 2).

[0100] (The 16th aspect) The negative thermal expansion material according to the 15th aspect, wherein x in the general formula (3) is 0.1 to 1.6.

[0101] (The 17th aspect) The negative thermal expansion material according to the 15th or 16th aspect, which exhibits negative thermal expansion in the temperature range of 100 to 500K.

[0102] (The 18th aspect) The negative thermal expansion material according to any one of the 15th to 17th aspects, wherein the linear expansion coefficient is -10 ppm / K or less in the temperature range of 100 to 500K.

[0103] (The 19th aspect) A composite material including the negative thermal expansion material according to any one of the 1st to 18th aspects and a positive thermal expansion material having a positive linear expansion coefficient.

[0104] (The 20th aspect) General formula (1) Cu 2-x R x V 2-y P y A method for manufacturing a negative thermal expansion material, including the step of preparing an aqueous solution containing a raw material of a compound represented by O7 (R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and satisfies 0 ≦ x ≦ 2, 0 < y < 2) and an organic acid.

[0105] (The 21st aspect) General formula (2) Zn 2-x T x P 2-y A yA method for producing a negative thermal expansion material including a step of preparing an aqueous solution containing a raw material of a compound represented by O7 (where T contains at least one element selected from Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, A contains at least one element selected from Al, Si, V, Ge, Sn, and 0 ≦ x < 2, 0 ≦ y ≦ 2 are satisfied. However, (x, y) = (0, 0) and (0, 2) are excluded.) and an organic acid.

[0106] (22nd Aspect) A component including a negative thermal expansion material according to any one of the 1st to 18th aspects, or a composite material including a negative thermal expansion material according to any one of the 1st to 18th aspects and a positive thermal expansion material having a positive linear expansion coefficient.

[0107] (23rd Aspect) A negative thermal expansion material according to any one of the 1st to 9th aspects in which the color changes by changing y in the general formula (1).

Industrial Applicability

[0108] Cu in the general formula (1) of the present disclosure 2-x R x V 2-y P y O7 (where R contains at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Zn, Sn, and 0 ≦ x ≦ 2, 0 < y < 2 are satisfied.), Zn in the general formula (2) 2-x T x P 2-y A y O7 (where T contains at least one element selected from Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, A contains at least one element selected from Al, Si, V, Ge, Sn, and 0 ≦ x < 2, 0 ≦ y ≦ 2 are satisfied. However, (x, y) = (0, 0) and (0, 2) are excluded.), and Ti in the general formula (3) 2-x M xOxides represented by any of the following (where M contains at least one element selected from Mg, Al, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, In, Sn, Sb, La, Ta, W, Bi, and satisfying 0 ≤ x < 2) can be used as thermal expansion inhibitors to counteract and suppress the thermal expansion exhibited by materials. Furthermore, zero thermal expansion materials that do not expand positively or negatively within a specific temperature range can also be produced.

[0109] Specifically, it can be used in precision optical components, mechanical parts, process equipment and tools, temperature compensation materials for fiber gratings, printed circuit boards, encapsulants for electronic components, thermal switches, refrigerator components, and satellite components, where changes in shape and dimensions due to temperature are undesirable. In particular, by creating a composite material in which a negative thermal expansion material is dispersed in a matrix phase of a resin with a large positive thermal expansion coefficient, it becomes possible to suppress and control thermal expansion even in resin materials, thus enabling its use in a wide range of applications.

Claims

1. General formula (1) Cu ２－ｘ R ｘ V ２－ｙ P ｙ O ７ The material contains an oxide represented by (where R is Zn, satisfying 0 < x ≤ 0.5 and 0.6 < y ≤ 1.5), the space group of the crystal structure of the oxide is C2 / c, and it exhibits negative thermal expansion in a temperature range of 100 to 500 K. Negative thermal expansion material.

2. It is characterized by having a coefficient of linear expansion of -10 ppm / K or less at 400 K. The negative thermal expansion material according to claim 1.

3. The negative thermal expansion material according to claim 1 or 2, characterized in that the coefficient of linear expansion is -10 ppm / K or less in a temperature range of 100 to 500 K.

4. The negative thermal expansion material according to any one of claims 1 to 3, characterized in that the color changes by changing y in general formula (1).

5. The oxide is characterized by being a polycrystalline sintered body. The negative thermal expansion material according to any one of claims 1 to 4.

Images