JP6998051B2 - Negative thermal expansion materials, complexes, and usage - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act The 2nd International Symposium on Negative Thermal Expansion and Related Materials (ISNTE-II), December 12, 2017 (Issued date) [Publications, etc.] and Reserved Materials (meeting name), December 13, 2017 (date) [Publications, etc.] Ceramic Society of Japan 2018 Annual Meeting Proceedings, March 1, 2018 (issue date) [ Publications, etc.] Ceramic Society of Japan 2018 Annual Meeting (meeting name), March 17, 2018 (Date) [Publications, etc.] Summary of the 73rd Annual Meeting of the Physical Society of Japan http: // w4. gakkai-web. net / (published address), March 1, 2018 (published date) [Publications, etc.] The 73rd Annual Meeting of the Physical Society of Japan (meeting name), March 22, 2018 (date) [Published Things, etc.] Angewandte Chemie International Edition, DOI: 10.1002 / anie. 201880482 https: // doi. org / 10.1002 / anie. 2018804882 (posted address), May 11, 2018 (posted date)

The present invention relates to negative thermal expansion materials, composites, and methods of use.

The perovskite-type compound PbVO ₃ has a large tetragonal distortion (due to the stereochemical activity of the 6s ² lone pair of Pb ²⁺ , the covalent bond of Pb-O, and the Pyramid Jahn-Teller deformation of V ⁴⁺ (3d ¹ ). It has a c / a ratio of 1.23). When a high pressure of 3 GPa is applied, a phase transition from a tetragonal crystal to a cubic crystal occurs, and a huge volume shrinkage of 10% or more and an insulator-metal transition occur (see Non-Patent Document 1). It has been reported that Pb _1-x Bi _x VO ₃ subjected to electron doping to V ⁴⁺ has lower tetragonal strain (c / a ratio) and tetragonal-cubic transition pressure than PbVO ₃ . See Non-Patent Document 2).

A. Belik, M. et al. Azuma et al, Chem. Mater. 17,269,2005. Meng Yamamoto et al., Proceedings of the 30th Autumn Symposium of the Ceramic Society of Japan, 3D07.

As a result of intensive studies on the above-mentioned compounds, the present inventors have shown that Pb 1- _x Bi _x VO ₃ exhibits a huge negative thermal expansion, and that Pb _1-x Bi _x VO ₃ has a Pb ²⁺ site. We have found that negative thermal expansion can be realized near room temperature by substituting La ³⁺ with La 3+, and have completed the present invention.

The present invention has been made in view of these circumstances, and one of the objects thereof is to provide a novel negative thermal expansion material.

One embodiment of the present invention is a negatively thermally expandable material. The negative thermal expansion material contains a compound represented by the following formula (1).
Pb _{1-x- y} My Bi _x VO ₃ ... (1)
[In the formula (1), M is one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Indicates the element of
Satisfy 0.05 ≤ x ≤ 0.4,
Satisfy 0.025 ≦ y ≦ 0.1. ]

Another aspect of the invention is a complex. The complex includes a negative thermal expansion material of the above aspect and a resin material.

Another aspect of the present invention is a method of using a compound represented by the following formula (2) as a negative thermal expansion material exhibiting negative thermal expansion at any temperature of 450K to 750K.
Pb _1-x Bi _x VO ₃ ... (2)
[In the formula (2), x satisfies 0.05 ≦ x ≦ 0.4. ]

According to the present invention, it is possible to provide a novel negative thermal expansion material.

It is a graph which shows the temperature dependence of the unit lattice volume of the negative thermal expansion material of Example 1. It is a graph which shows the temperature dependence of the unit lattice volume of the negative thermal expansion material of Example 2. It is a graph which shows the temperature dependence of the unit lattice volume of the negative thermal expansion material of Example 3. It is a graph which shows the temperature dependence of the unit lattice volume of the negative thermal expansion material of Example 4. It is a graph which shows the temperature dependence of the unit lattice volume of the negative thermal expansion material of Example 5. It is a graph which shows the temperature dependence of the unit lattice volume of the negative thermal expansion material of Example 6. It is a graph which shows the temperature dependence of the unit lattice volume of the negative thermal expansion material of Example 7. It is a graph which shows the temperature dependence of the unit lattice volume of the negative thermal expansion material of Example 8. It is a graph which shows the temperature dependence of the linear thermal expansion rate of the negative thermal expansion material of Example 5. It is a graph which shows the temperature dependence of the linear thermal expansion rate of the negative thermal expansion material of Example 8.

(Embodiment 1)
The negative thermal expansion material according to the first embodiment is a compound in which a part of Pb is co-substituted with metal elements M and Bi in PbVO ₃ which is a mother substance. Specifically, the negative thermal expansion material according to the first embodiment has a negative thermal expansion property and contains a compound represented by the following formula (1).
Pb _{1-x- y} My Bi _x VO ₃ ... (1)
[In the formula (1), M is one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Indicates the element of
Satisfy 0.05 ≤ x ≤ 0.4,
Satisfy 0.025 ≦ y ≦ 0.1. ]

PbVO ₃ , which is the parent substance of the compound represented by the above formula (1), is a perovskite-type compound having a huge tetragonal strain (c / a ratio 1.23). A structural phase transition from tetragonal (P4 mm) to cubic (Pm-3 m) with a very large volume change ΔV / V = -10.6% occurs when pressure is applied, but the structural phase due to temperature rise under normal pressure No metastasis occurs. By partially substituting divalent lead ions with trivalent bismuth ions and element M ions for electron doping, huge negative thermal expansion (maximum ΔV) occurs in the temperature range of 180K to 550K across room temperature. / V = -8.8%) can be realized.

In the above formula (1), the element M is preferably selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Is La.

The negative thermal expansion material according to the present embodiment exhibits negative thermal expansion at any temperature of 180K to 550K. By changing the ratio (that is, y) of the element M in the compound of the above formula (1), the temperature range showing negative thermal expansion can be changed. From the viewpoint of achieving a larger negative thermal expansion, x is preferably 0.1 to 0.2, and y is preferably 0.06 or less.

The negative thermal expansion material of the present embodiment is dispersed in a resin material such as engineering plastic, and the material selection and each component are selected so that the thermal expansion of the resin material is offset by the negative thermal expansion of the negative thermal expansion material. By setting the content, a zero thermal expansion material can be obtained.

(Manufacturing method of negative thermal expansion material)
The method for producing the compound represented by the above formula (1) is not particularly limited, but a method capable of synthesizing a composite metal oxide in which each metal element is uniformly dissolved and forming an arbitrary shape is preferable. For example, when each oxide of Pb, Bi, M, and V is mixed at the same molar ratio as the target product and sintered while applying a high pressure (for example, 2 GPa or more), composite metal oxidation in which each metal element is uniformly dissolved. You get things. When the obtained oxide is crushed, molded, and baked at a temperature equal to or lower than the sintering temperature, a thermal expansion suppressing member made of the compound represented by the general formula (1) can be obtained. In addition, the negative thermal expansion material according to the present embodiment is not limited to the above-mentioned production method, but can also be produced by growing a thin film on a single crystal substrate by a sputtering method, a chemical solution method, a laser ablation method, or the like. Can be done.

(Embodiment 2)
The method of use according to the second embodiment is a method of using a compound represented by the following formula (2) as a negative thermal expansion material exhibiting negative thermal expansion at any temperature of 450K to 750K.
Pb _1-x Bi _x VO ₃ ... (2)
[In the formula (2), x satisfies 0.05 ≦ x ≦ 0.4. ]

As described above, PbVO ₃ , which is the parent material of the compound represented by the above formula (2), has a huge tetragonal strain, and a huge volume shrinkage occurs when pressure is applied, but negative thermal expansion due to temperature rise occurs. can not see. By substituting a part of Pb ²⁺ with Bi ³⁺ , the tetragonal strain is greatly reduced, and the temperature rise under normal pressure causes a huge negative thermal expansion in the temperature range of 450K to 750K. Therefore, the compound represented by the above formula (2) is useful as a negative thermal expansion material exhibiting negative thermal expansion at any temperature of 450K to 750K. Such a negative thermal expansion material is also one of the embodiments of the present invention.

(Embodiment 3)
The complex according to the third embodiment includes a negative heat-expandable material according to any one of the above-described embodiments, and a resin material or a metal material having a positive heat-expandability. The resin material used for the composite is not particularly limited, and examples thereof include epoxy resin, phenol resin, and polycarbonate. The metal material used for the composite is not particularly limited, and examples thereof include copper and aluminum.

The mixing ratio (volume ratio) of the negative heat-expandable material and the resin material or the metal material depends on the negative heat-expandable material used and the coefficient of thermal expansion of the resin material or the metal material, for example, from 5:95. It is 80:20. According to this embodiment, the positive thermal expansion of the resin material or the metal material can be offset by the negative thermal expansion of the negative thermal expansion material. This makes it possible to provide a material having a small ratio of dimensional change with respect to temperature change.

The present invention is not limited to the above-described embodiments, and it is possible to combine the embodiments and to make various design changes and other modifications based on the knowledge of those skilled in the art. Also included in the scope of the invention are embodiments that have been combined or modified. For example, a negative thermal expansion material containing both the compound represented by the above formula (1) and the compound represented by the above formula (2) is also included in the scope of the present invention.

Hereinafter, examples of the present invention will be described, but these examples are merely examples for suitably explaining the present invention, and do not limit the present invention in any way.

(Examples 1 to 8)
In an argon-filled glove box, the starting materials PbO, Bi ₂ O ₃ , La ₂ O ₃ , V ₂ O ₃ , and V ₂ O ₅ were mixed at a stoichiometric ratio and encapsulated in a Pt capsule. Then, the sample was treated with a cubic anvil type high pressure synthesizer under the conditions of 6 GPa, 1200 ° C. and 1 hour to prepare a negative thermal expansion material of Examples 1 to 8. The compositions of the materials of Examples 1 to 8 are as follows.
Example 1: Pb _0.85 La _0.05 Bi _0.1 VO ₃
Example 2: Pb _0.84 La _0.06 Bi _0.1 VO ₃
Example 3: Pb _0.82 La _0.08 Bi _0.1 VO ₃
Example 4: Pb _0.775 La _0.025 Bi _0.2 VO ₃
Example 5: Pb _0.76 La _0.04 Bi _0.2 VO ₃
Example 6: Pb _0.75 La _0.05 Bi _0.2 VO ₃
Example 7: Pb _0.8 Bi _0.2 VO ₃
Example 8: Pb _0.7 Bi _0.3 VO ₃

For each negative thermal expansion material of Examples 1-8, a synchrotron X-ray diffraction (SXRD) pattern at λ = 0.42 Å using a large Debye-Scherrer camera installed in the BL02B2 beamline of SPring-8. Was measured and analyzed using RIETAN-FP software (S. Kawaguchi, et al., Rev. Sci. Instrument. 2017, 88, 085111; F. Izumi, K. Momma, Apple. Synchrotron. 2007, 130, 15-20). The linear thermal expansion coefficient was measured at 150K to 460K using a thermomechanical analyzer (TMA8310, Rigaku) in the sintered body of the negative thermal expansion material of Examples 5 and 8 having a diameter of 3 mm and a height of 1 mm. .. FIGS. 1 to 8 show the temperature dependence of the unit cell volume of each negative thermal expansion material of Examples 1 to 8. FIG. 9 shows the temperature dependence of the linear thermal expansion coefficient of the negative thermal expansion material of Example 5, and FIG. 10 shows the temperature dependence of the linear thermal expansion coefficient of the negative thermal expansion material of Example 8. Table 1 shows the temperature range and the rate of change in lattice volume showing the negative thermal expandability of each of the negative thermal expansion materials of Examples 1 to 8.

As shown in FIGS. 1 to 6, in Examples 1 to 6, it was confirmed that by simultaneously substituting a part of Pb with Bi and La, a large negative thermal expansion occurs in a temperature range sandwiching room temperature. As shown in FIGS. 7 and 8, in Examples 7 and 8, it was confirmed that by substituting a part of Pb with Bi, a large negative thermal expansion occurs in the temperature range of 450K to 750K.

As shown in FIG. 9, in Example 5, macroscopic negative thermal expansion was confirmed in the temperature range of 280 to 310 K. The volume change (ΔV / V to 3ΔL / L) estimated from the expansion measurement value of the sintered body of Example 5 was about 8.5%. This was larger than the lattice volume change (ΔV / V = −6.7%) obtained from the X-ray diffraction of the negative thermal expansion material of Example 5 shown in Table 1. As shown in FIG. 10, in Example 8, macroscopic negative thermal expansion was confirmed in the temperature range of 460 to 500 K.

The present invention can be used for materials having negative thermal expansion properties.

Claims (5)

A negative thermal expandable material with negative thermal expandability,
A negative thermal expansion material comprising a compound represented by the following formula (1).
Pb _{1-x- y} My Bi _x VO ₃ ... (1)
[In the formula (1), M is one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Indicates the element of
Satisfy 0.05 ≤ x ≤ 0.4,
Satisfy 0.025 ≦ y ≦ 0.1. ] The negative thermal expansion material according to claim 1, wherein M is La. The negative thermal expansion material according to claim 1 or 2, wherein the negative thermal expansion is exhibited at any temperature of 180K to 480K. A composite comprising the negative heat-expandable material according to any one of claims 1 to 3 and a resin material or a metal material having a positive heat-expandability. A method for using a compound represented by the following formula (2) as a negative thermal expansion material exhibiting negative thermal expansion at any temperature of 450K to 750K.
Pb _1-x Bi _x VO ₃ ... (2)
[In the formula (2), x satisfies 0.05 ≦ x ≦ 0.4. ]

Images