Perovskite material with wide temperature range and strong negative thermal expansion effect as well as preparation method and application of perovskite material
The perovskite material PbTiO3-xH2x was synthesized by high-temperature and high-pressure solid-state reaction method, which enhanced and broadened its negative thermal expansion effect, and solved the problems of weak effect and narrow temperature range of existing negative thermal expansion materials. It is suitable for precision optical devices and aerospace structural materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INSTITUTE OF PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2026-01-23
- Publication Date
- 2026-05-12
AI Technical Summary
The types of existing negative thermal expansion materials are limited, their negative thermal expansion effect is weak and their effective working temperature range is narrow, making it difficult to achieve wide temperature range and high precision matching with positive expansion materials, which limits their engineering applications.
The perovskite material PbTiO3-xH2x (0
It significantly enhances the negative thermal expansion effect and widens the operating temperature range to 300 K to 790 K, achieving high-precision temperature range matching, and is suitable for precision optical devices, electronic packaging and aerospace structural materials.
Smart Images
Figure CN122010558A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of new materials technology. Specifically, this invention relates to a perovskite material with a wide temperature range and strong negative thermal expansion effect, its preparation method, and its applications. Background Technology
[0002] Thermal expansion and contraction of materials is a ubiquitous physical phenomenon. In fields such as precision machinery, electronic devices, optical systems, and structural engineering, mismatches in the coefficients of thermal expansion between components can lead to stress concentration, performance degradation, and even device failure, making it one of the key issues restricting the development of high-precision and high-reliability technologies.
[0003] Negative thermal expansion materials exhibit the characteristic of "thermal contraction and cold expansion" within a certain temperature range, providing a revolutionary solution for precisely controlling the thermal expansion behavior of composite materials. By combining negative thermal expansion materials with conventional positive expansion materials, it is hoped to achieve a design where the overall thermal expansion coefficient of the material can be adjusted "from zero". Given its significant application value, negative thermal expansion materials have been included in the National Key Development Guidance Catalogue for the Industrialization of Frontier Materials (First Batch), becoming one of the key frontier materials for development.
[0004] However, the large-scale application of negative thermal expansion materials still faces a core bottleneck: the types of negative thermal expansion materials discovered so far are limited, and most of them suffer from weak negative thermal expansion effects and narrow effective operating temperature ranges. This makes it difficult to achieve high-precision matching with widely used positive expansion materials over a wide temperature range and throughout the entire life cycle, greatly limiting their engineering applications.
[0005] Among numerous negative thermal expansion materials, perovskite-structured lead titanate (PbTiO3) is a classic and important ferroelectric material, attracting considerable attention due to its excellent ferroelectric / piezoelectric properties and inherent negative thermal expansion characteristics. Its stable and highly tunable crystal structure allows for performance tuning through various cation doping methods (equivalent or non-equivalent substitution of Pb or Ti sites), providing possibilities for designing novel negative thermal expansion materials.
[0006] However, the negative thermal expansion properties of pure PbTiO3 (such as its coefficient of expansion and operating temperature range) are insufficient to meet stringent application requirements. More challenging is that most modification studies of PbTiO3 (such as common cation doping), while optimizing other properties, often weaken its inherent negative thermal expansion effect or shrink its negative thermal expansion temperature range. Therefore, how to significantly broaden the operating temperature range of PbTiO3 while maintaining or enhancing its negative thermal expansion effect has become a pressing technical challenge in this field. Summary of the Invention
[0007] One objective of this invention is to provide a new wide-temperature-range negative thermal expansion material based on existing PbTiO3-based negative thermal expansion materials, which has a strong negative thermal expansion effect while also having a wide operating temperature range.
[0008] Another object of the present invention is to provide a method for preparing the perovskite material of the present invention, which has a wide temperature range and a strong negative thermal expansion effect, and the method is highly reproducible and the obtained sample has high purity.
[0009] The above-mentioned objective of the present invention is achieved by a method including the following steps.
[0010] In the context of this invention, the term "normal temperature" means 15-30°C, and "normal pressure" means a pressure of about 90 kPa to about 110 kPa.
[0011] In the context of this invention, the term "room temperature" refers to 25°C, or 298K.
[0012] In the context of this invention, the working temperature range refers to the temperature range in which a material exhibits negative thermal expansion behavior or a negative thermal expansion temperature range. The terms "working temperature range" and "negative thermal expansion temperature range" are used interchangeably.
[0013] In a first aspect, the present invention provides a perovskite material having a wide temperature range and a strong negative thermal expansion effect, having the following chemical formula:
[0014] PbTiO 3-x H 2x Where 0 < x ≤ 0.15;
[0015] The average volumetric expansion coefficient of the perovskite material is -2.6 × 10⁻⁶. -5 / K to -2.50×10 -5 / K.
[0016] Preferably, in the perovskite material with a wide temperature range and strong negative thermal expansion effect described in this invention, the perovskite material has a tetragonal crystal structure with a space group of P4mm.
[0017] Preferably, in the perovskite material with a wide temperature range and strong negative thermal expansion effect described in this invention, the perovskite material exhibits a negative thermal expansion effect in the temperature range of 300K to 790K.
[0018] Preferably, in the perovskite material with a wide temperature range and strong negative thermal expansion effect described in this invention, the average volumetric expansion coefficient of the perovskite material is -2.52 × 10⁻⁶. -5 / K to -2.50×10 -5 / K.
[0019] Secondly, the present invention provides a method for preparing a perovskite material with a wide temperature range and a strong negative thermal expansion effect, comprising the following steps:
[0020] (1) PbO, TiO2 and TiH2 are mixed in a preset molar ratio to obtain a raw material mixture, which is then placed in a cylindrical crucible and a closed mold.
[0021] (2) Place the closed mold containing the raw material mixture in a high-pressure synthesis device, and heat and pressurize it to 800-1400℃ and 1-30 Gpa respectively, and maintain it for 0.5-10 hours. Then, cool and pressurize it to room temperature and normal pressure respectively.
[0022] (3) Demold and grind the product to obtain the perovskite material.
[0023] Preferably, in the preparation method of the present invention, step (1) further includes pretreatment by keeping the raw material mixture at 300-500°C for 0.5-10 hours.
[0024] Preferably, in the preparation method of the present invention, the heating rate in step (2) is 10-250℃ / min and the pressure rate is 0.01-0.30 Gpa / min.
[0025] Preferably, in the preparation method of the present invention, the cooling rate in step (2) is 10-400℃ / min and the pressure reduction rate is 0.001-0.15 Gpa / min.
[0026] Preferably, in the preparation method of the present invention, the molar ratio of PbO, TiO2 and TiH2 in the raw material mixture is 1:(1-x):x, wherein the value of x is consistent with x in the chemical formula of the perovskite material.
[0027] Preferably, in the preparation method of the present invention, the purity of PbO, TiO2 and TiH2 is ≥99% by weight and the particle size is ≤200 μm.
[0028] Preferably, in the preparation method of the present invention, the closed mold includes the following components: a pyrophyllite pressure-transmitting sealing block, a boron nitride insulating layer, a graphite heater, a molybdenum electrode sheet, and a ceramic sample tube; the cylindrical crucible is placed inside the ceramic sample tube.
[0029] Preferably, in the preparation method of the present invention, the cylindrical crucible is made of gold or platinum.
[0030] Thirdly, the present invention provides the application of the perovskite material of the present invention having a wide temperature range and a strong negative thermal expansion effect, or the perovskite material of the present invention having a wide temperature range and a strong negative thermal expansion effect prepared by the method of the present invention, in precision optical devices.
[0031] The present invention has the following beneficial effects:
[0032] (1) Achieving a dual breakthrough in "enhancing" and "expanding" the negative thermal expansion performance.
[0033] The effect is significantly enhanced: the prepared material exhibits a stronger negative thermal expansion effect over a wide temperature range. For example, when x = 0.10, its average volumetric expansion coefficient reaches -2.50 × 10⁻⁶. -5 / K, which is superior to undoped pure PbTiO3 (approximately -1.99 × 10⁻⁶). -5 / K).
[0034] The temperature range has been greatly expanded: the negative thermal expansion behavior of the material is stable in a wide temperature range of 300 K to 790 K, and the effective working temperature range has been significantly expanded, which is more conducive to matching with actual application scenarios.
[0035] (2) High-purity, single-phase high-quality materials were obtained.
[0036] A high-purity sample with a single crystal structure and no impurity phases was successfully prepared using a high-temperature, high-pressure synthesis method. Synchrotron radiation XRD and refinement results confirmed that the sample is a pure tetragonal perovskite phase with good structural integrity, laying the foundation for reliable performance.
[0037] (3) The preparation method is stable, controllable and highly reproducible.
[0038] The high-temperature and high-pressure solid-phase reaction method adopted has a clear process route, and the range of key parameters (temperature, pressure, time, heating and cooling rates) is clearly defined, resulting in strong process controllability.
[0039] This method has high repeatability and can stably prepare products with consistent performance. It overcomes the problems of uneven composition and many impurities that may exist in traditional solid-phase methods, which is conducive to the exploration of large-scale preparation.
[0040] (4) A novel and effective material modification strategy is provided.
[0041] This invention innovatively employs a chemical design that partially replaces oxygen (O) sites with hydrogen (H). By introducing TiH2 as a hydrogen source, hydrogen was successfully incorporated into the perovskite lattice under high pressure. This opens up a new technical path for controlling the negative thermal expansion properties of PbTiO3-based materials and has significant scientific implications.
[0042] (5) It has broad application potential and practical value.
[0043] This material possesses strong negative thermal expansion effect, wide operating temperature range and high stability, making it an ideal functional component for preparing zero-expansion or controllable expansion composite materials, with significant application prospects in fields such as precision optical devices, electronic packaging, aerospace structural materials, and precision measurement equipment.
[0044] In summary, this invention not only creatively synthesizes a novel negative thermal expansion material with excellent performance, but also provides a reliable and efficient preparation method, solving the problems of weak effect, narrow temperature range, and difficulty in modification that are common in existing negative thermal expansion materials. It has significant technological advancement and industrial application value. Attached Figure Description
[0045] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:
[0046] Figure 1 The perovskite material PbTiO2 prepared in Example 1 is shown. 3-x H 2x (x = 0.10) XRD pattern at room temperature;
[0047] Figure 2 The perovskite material PbTiO2 prepared in Example 2 is shown. 3-x H 2x (x = 0.15) XRD pattern at room temperature;
[0048] Figure 3 The perovskite materials PbTiO2 prepared in Examples 1 and 2 are shown respectively. 3-x H 2x (x = 0.10) and PbTiO 3-x H 2x The lattice parameter of (x = 0.15) as a function of temperature is plotted.
[0049] Figure 4 The perovskite materials PbTiO2 prepared in Examples 1 and 2 are shown respectively. 3-x H 2x (x = 0.1) and PbTiO 3-x H 2x The curve showing the change in unit cell volume as a function of temperature for x = 0.15.
[0050] Figure 5 This illustrates PbTiO prepared according to Example 1. 3-x H 2x (x = 0.10) XRD pattern data of the material;
[0051] Figure 6 PbTiO2 prepared according to Example 2 is shown. 3-x H2x (x = 0.15) XRD pattern data of the material. Detailed Implementation
[0052] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.
[0053] It should be noted that, unless otherwise specified, all raw materials used in the following implementation examples are commercially available. PbO, TiO2, and TiH2 were all purchased from Alfa, with a purity of ≥99% by weight and a particle size of ≤200 μm.
[0054] Example 1
[0055] PbTiO 3-x H 2x Preparation of (x = 0.10)
[0056] (1) Ingredient preparation and pretreatment
[0057] The raw materials PbO, TiO2 and TiH2 were mixed in a molar ratio of 1:0.9:0.1 and pretreated at 500℃ for 5 hours.
[0058] (2) High temperature and high pressure synthesis
[0059] The pretreated sample is loaded into a cylindrical crucible, and then the Au cylindrical crucible containing the sample is placed into a closed mold. The closed mold is placed in a high-pressure synthesis device (six-sided top press device), and heating and pressurization are carried out simultaneously. The temperature is increased to 1350°C at a heating rate of 100°C / min, and the pressure is increased to 20 GPa at a pressurization rate of 0.20 GPa / min. This temperature and pressure are maintained for 5 hours, and then the temperature is reduced to room temperature at a cooling rate of 200°C / min and the pressure is reduced to atmospheric pressure at a depressurization rate of 0.10 GPa / min.
[0060] (3) Post-processing
[0061] Remove the processed sample and demold it. Grind the processed sample thoroughly to obtain a sample with the chemical composition PbTiO. 3-x H 2x (x = 0.10) negative thermal expansion material.
[0062] Example 2
[0063] PbTiO 3-x H 2x Preparation of (x = 0.15)
[0064] (1) Ingredient preparation and pretreatment
[0065] The raw materials PbO, TiO2 and TiH2 were prepared and mixed in a molar ratio of 1:0.85:0.15, and then pretreated at 350℃ for 10 hours.
[0066] (2) High temperature and high pressure synthesis
[0067] The pretreated sample is loaded into a cylindrical crucible, and then the Au cylindrical crucible containing the sample is placed into a closed mold. The closed mold is placed in a high-pressure synthesis device (six-sided top press device), and heating and pressurization are carried out simultaneously. The temperature is increased to 900°C at a heating rate of 200°C / min, and the pressure is increased to 10 GPa at a pressurization rate of 0.1 GPa / min. This temperature and pressure are maintained for 5 hours, and then the temperature is reduced to room temperature at a cooling rate of 50°C / min and the pressure is reduced to atmospheric pressure at a depressurization rate of 0.15 GPa / min.
[0068] (3) Post-processing
[0069] Remove the processed sample and demold it. Grind the processed sample thoroughly to obtain a sample with the chemical composition PbTiO. 3-x H 2x (x = 0.15) negative thermal expansion material.
[0070] Crystal structure characterization
[0071] The crystal structure of the lead titanate-based negative thermal expansion materials obtained in Examples 1 and 2 was characterized, and the crystal structure and negative thermal expansion properties of the materials were determined by XRD data refinement and theoretical calculations. The specific steps are as follows:
[0072] The purity of a sample can be roughly determined by XRD testing using an X-ray powder diffractometer manufactured by Huber GmbH, Germany. This invention determines the precise crystal structure of perovskite oxides through high-quality samples and high-precision diffraction spectra. Specifically, the sample was tested using X-ray diffraction (XRD) at room temperature (i.e., 298 K) with a wavelength of 1.54 Å.
[0073] The obtained XRD data were refined using Rietveld refinement with Fullprof software to determine the crystal structure of the sample. Based on the refinement results, the lattice parameters at different temperatures were obtained, and the intrinsic thermal expansion coefficient of the sample could then be calculated.
[0074] Figure 1 and Figure 2 The perovskite materials PbTiO2 prepared in Examples 1 and 2 are shown respectively. 3-x H 2x (x=0.10, Figure 1 ) and PbTiO 3-x H2x (x=0.15, Figure 2 XRD pattern at room temperature.
[0075] At room temperature, XRD results showed almost no impurities besides the main phase, reflecting the sample quality. All diffraction peaks of the main phase could be indexed using a tetragonal lattice with the same space group P4mm as PbTiO3. Therefore, PbTiO3... 3-x H 2x (0 < x ≤ 0.15) The material has a tetragonal crystal structure.
[0076] The perovskite-type lead titanate-based negative thermal expansion materials prepared in Examples 1 and 2 of this invention were tested at room temperature using X-ray diffraction with a wavelength of 1.54 Å. The characteristic diffraction peaks of the XRD diffraction patterns obtained by fitting were respectively located at... Figure 5 (x=0.10) and Figure 6 As shown in (x=0.15), (hkl) is the corresponding crystal plane, and 2T represents the 2θ angle.
[0077] Figure 5 As shown, PbTiO 3-x H 2x (x=0.1) The X-ray powder diffraction pattern expressed in 2θ angle at a wavelength of 1.54 Å has diffraction peaks at 21.3744°, 22.7837°, 31.4395°, 32.4407°, 39.1800°, 43.5416°, 46.5364°, 49.6957°, 51.7487°, 52.4201°, 55.3320°, and 57.2425°. The measurement error of the 2θ angle is ±0.005°.
[0078] Figure 6 As shown, PbTiO 3-x H 2x (x=0.15) The X-ray powder diffraction pattern expressed in 2θ angles at a wavelength of 1.54 Å has diffraction peaks at 21.3742°, 22.7842°, 31.4397°, 32.4415°, 39.1805°, 43.5411°, 46.5375°, 49.6954°, 51.7496°, 52.4214°, 55.3320°, and 57.2435°. The measurement error of the 2θ angle is ±0.005°.
[0079] In summary, the perovskite-type lead titanate-based negative thermal expansion material of the present invention exhibits diffraction peaks at 21.374°, 22.784°, 31.440°, 32.441°, 39.181°, 43.541°, 46.537°, 49.696°, 51.749°, 52.421°, 55.332°, and 57.243° in its X-ray powder diffraction pattern at a wavelength of 1.54 Å, expressed in 2θ angles. The 2θ angle measurement error is ±0.005°.
[0080] Characterization of negative thermal expansion properties
[0081] At room temperature, PbTiO 3-x H 2x (0 < x ≤ 0.15) The space group of the bulk sample is P4mm. By replacing the O sites of the PbTiO3-based negative thermal expansion material with H, the prepared material can enhance the axial ratio of PbTiO3, thereby enhancing its negative thermal expansion effect and widening its negative thermal expansion temperature range. 3-x H 2x (0 < x ≤ 0.15) Lattice parameters and negative thermal expansion properties are as follows Figure 2-3 As shown.
[0082] Figure 3 The perovskite materials PbTiO2 prepared in Examples 1 and 2 are shown respectively. 3-x H 2x (x=0.1) and PbTiO 3- x H 2x The lattice parameter (x=0.15) varies with temperature. Figure 3 It can be seen that as the temperature increases, PbTiO 3-x H 2x (x=0.10) and PbTiO 3-x H 2x (x=0.15) The c-axis gradually decreases, while the a(b)-axis gradually increases.
[0083] Figure 4 The perovskite materials PbTiO2 prepared in Examples 1 and 2 are shown respectively. 3-x H 2x (x=0.10) and PbTiO 3- x H 2x A graph showing the change in unit cell volume (x=0.15) with temperature. Figure 3 It can be seen that all the materials exhibit negative thermal expansion behavior, and the average volume expansion coefficient of the sample with x=0.10 is -2.50×10⁻⁶. -5 / K (room temperature to 790 K), x=0.15 The average volumetric expansion coefficient of the sample is -2.52×10-5 / K (room temperature to 790 K), compared to undoped PbTiO3 (-1.99 × 10⁻⁶ K), -5 / K, from room temperature to 763 K), the negative thermal expansion effect is significantly enhanced, and the negative thermal expansion temperature range is widened.
[0084] The above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications or substitutions that are obvious to those skilled in the art should fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
[0085] Although the invention has been described and illustrated in conjunction with certain embodiments, it should be understood that various modifications of the invention will be apparent to those skilled in the art upon reading this specification. Therefore, it should be understood that the invention disclosed herein is intended to cover such modifications falling within the scope of the appended claims.
Claims
1. A perovskite material with a wide temperature range and strong negative thermal expansion effect, characterized in that, The perovskite material has the following chemical formula: PbTiO 3-x H 2x Where 0 < x ≤ 0.15; The average volumetric expansion coefficient of the perovskite material is -2.6 × 10⁻⁶. -5 / K to -2.50×10 -5 / K.
2. The perovskite material with a wide temperature range and strong negative thermal expansion effect according to claim 1, wherein, The perovskite material has a tetragonal crystal structure with a space group of P4mm.
3. The perovskite material with a wide temperature range and strong negative thermal expansion effect according to claim 1, wherein, The perovskite material exhibits a negative thermal expansion effect in the temperature range of 300K to 790K.
4. The perovskite material with a wide temperature range and strong negative thermal expansion effect according to claim 1, wherein, The average volumetric expansion coefficient of the perovskite material is -2.52 × 10⁻⁶. -5 / K to -2.50×10 -5 / K.
5. A method for preparing a perovskite material with a wide temperature range and strong negative thermal expansion effect as described in any one of claims 1-4, characterized in that, The method includes the following steps: (1) PbO, TiO2 and TiH2 are mixed in a preset molar ratio to obtain a raw material mixture, which is then placed in a cylindrical crucible and a closed mold. (2) Place the closed mold containing the raw material mixture in a high-pressure synthesis device, and heat and pressurize it to 800-1400℃ and 1-30 Gpa respectively, and maintain it for 0.5-10 hours. Then, cool and pressurize it to room temperature and normal pressure respectively. (3) Demold and grind the product to obtain the perovskite material.
6. The preparation method according to claim 5, wherein, Step (1) further includes pretreatment by keeping the raw material mixture at 300-500℃ for 0.5-10 hours.
7. The preparation method according to claim 5, wherein, In step (2), the heating rate is 10-250℃ / min and the pressurization rate is 0.01-0.30 Gpa / min; Preferably, in step (2), the cooling rate is 10-400℃ / minute and the pressure reduction rate is 0.001-0.15 Gpa / minute.
8. The preparation method according to claim 5, wherein, The molar ratio of PbO, TiO2 and TiH2 in the raw material mixture is 1:(1-x):x, where the value of x is consistent with x in the chemical formula of the perovskite material.
9. The preparation method according to claim 5, wherein, The purity of PbO, TiO2 and TiH2 is ≥99% by weight and the particle size is ≤200 μm.
10. The application of the perovskite material with a wide temperature range and strong negative thermal expansion effect as described in any one of claims 1 to 4, or the perovskite material with a wide temperature range and strong negative thermal expansion effect prepared by the method as described in any one of claims 5 to 9, in precision optical devices.