A near-zero expansion high-entropy oxide (Al0.2Sc0.2Fe0.2Ga0.2X0.2)2W3O12 and its preparation method.
By preparing a high-entropy oxide (Al0.2Sc0.2Fe0.2Ga0.2X0.2)2W3O12, the problem of unstable thermal expansion properties of the material was solved, achieving near-zero expansion characteristics and good thermal stability, making it suitable for high-end technology fields such as electronic devices and aerospace.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-18
- Publication Date
- 2026-04-03
AI Technical Summary
Existing technologies cannot effectively control the thermal expansion properties of materials, resulting in dimensional instability of devices at different operating temperatures, which affects performance and lifespan.
A near-zero expansion high-entropy oxide was prepared by using the preparation method of high-entropy oxide (Al0.2Sc0.2Fe0.2Ga0.2X0.2)2W3O12, and by solid-state sintering and pressing process, the thermal expansion coefficient was controlled.
A high-entropy ZTE material exhibiting near-zero thermal expansion characteristics within a certain temperature range has been successfully prepared. It possesses good thermal stability and low cost, making it suitable for industrial production and application in fields such as electronic devices and aerospace.
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Figure CN118619654B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of thermal expansion materials technology, specifically relating to a near-zero expansion high-entropy oxide (Al). 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 And its preparation method. Background Technology
[0002] In recent years, fields such as microelectronics, optoelectronic communications, and aerospace have developed rapidly. The demand for materials with high-precision dimensions is increasing, and the dimensional stability and long lifespan of devices under different operating temperatures are crucial. Mismatches in the coefficients of thermal expansion, coupled with temperature variations in the material's environment, can lead to thermal stress, resulting in performance degradation or permanent damage to devices. Materials with low expansion, especially near-zero expansion, are beneficial for improving the geometric stability of these materials and devices. The discovery of negative thermal expansion (NTE) behavior in compounds has opened up possibilities for developing materials with controllable or near-zero coefficients of thermal expansion.
[0003] Since the development of the wide-temperature-range negative expansion compound ZrW₂O₈, the thermal expansion properties of materials such as metal cyanides, metal fluorides, and Mn₃AN (A = Cu, Zn, Ge, Sn, Ag) have been reported. Among them, A₂M₃O₈... 12 Due to its excellent chemical flexibility, A has attracted widespread attention. 3+ The cation can be a transition metal or rare earth element that accepts octahedral sites, while M 6+ That is W 6+ Or Mo 6+ This characteristic provides a variety of options for cation substitution. Regarding A2M3O 12 Multiple studies on molybdates and tungstates have reported negative thermal expansion (NTE) following the phase transition from monoclinic to orthorhombic structures. Both compounds consist of angle-sharing AO6 octahedra and MO4 tetrahedra. In the relatively loose orthorhombic phase structure, the lateral movement of oxygen atoms in the AOM bonds appears to contribute to the NTE. Notably, A2M3O 12 The good chemical flexibility of this family makes it very promising for the regulation of thermal expansion properties. Currently, achieving ZTE through thermal expansion property regulation mainly involves chemical methods, namely ion substitution, to control the coefficient of thermal expansion of the compounds.
[0004] Since 2004, high-entropy solid solution methods have attracted considerable attention from researchers. When the concept of high entropy was introduced into the ceramics field, high-entropy ceramics (HECs) with various structures were designed and developed, such as germanite (or defective zeolite) and perovskite. Compared to single-component ceramics, HECs exhibit attractive properties, including excellent thermal stability, tunable thermal expansion, remarkable phase stability, and low thermal conductivity. Currently, research on the applications of HECs mainly focuses on thermal protection and corrosion prevention, with few reports on their application in the field of negative thermal expansion. Extending the concept of high-entropy materials to the field of negative thermal expansion materials, and controlling their thermal expansion properties and phase transition temperatures to obtain zero-thermal-expansion materials with a wide operating temperature range, has significant scientific implications and broad application prospects. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a near-zero expansion high-entropy oxide (Al). 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 And its preparation method.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A near-zero expansion high-entropy oxide with the molecular formula (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 , where X = Cr or In.
[0008] The preparation method of the near-zero expansion high-entropy oxide includes the following steps:
[0009] (1) Select Al2O3, Sc2O3, Fe2O3, Ga2O3, X2O3 and W2O3 as raw materials, and mix Al2O3, Sc2O3, Fe2O3, Ga2O3, X2O3 and W2O3 according to the target product (Al 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 The stoichiometric molar ratio of Al∶Sc∶Fe∶Ga∶X∶W = 0.4∶0.4∶0.4∶0.4∶3 was ground and mixed evenly.
[0010] (2) The mixed powder obtained in step (1) is directly sent to sintering, sintered at 700~1100 ℃ for 5~10 h, cooled to room temperature and taken out, and then ground again;
[0011] (3) Press the mixed powder obtained in step (2) into tablets and then send them to sinter. Sinter at 700~1100 ℃ for 5~10 h to obtain the target product.
[0012] Preferably, in step (1), wet grinding is used, and ethanol is added when grinding the raw materials. The amount added is based on wetting Al2O3, Sc2O3, Fe2O3, Ga2O3, X2O3 and W2O3.
[0013] Preferably, in step (1), the mass purity of the raw materials Al2O3, Sc2O3, Fe2O3, Ga2O3, X2O3 and W2O3 is 99~99.99%.
[0014] Preferably, in steps (2) and (3), the heating rate is 5~10 ℃ / min.
[0015] Preferably, in step (3), the mixed powder is pressed into a cylindrical embryo with a diameter of 8-10 mm and a height of 3-6 mm during tableting.
[0016] Preferably, in step (3), the pressure during tablet compression is 4~10 MPa and the holding time is 2~5 min.
[0017] Beneficial effects:
[0018] (1) This invention is the first to propose a molecular formula of (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 The high-entropy ZTE material was synthesized, and its phase purity and thermal expansion properties were characterized. The structure showed that (Al) was successfully prepared. 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 All materials exhibit near-zero thermal expansion characteristics within a certain temperature range;
[0019] (2) The high-entropy ZTE material of the present invention has a thermal expansion coefficient close to zero and good thermal stability. The preparation process is simple and the cost is low, making it suitable for industrial production. It is expected to be widely used in high-end technology fields such as electronic devices, aerospace and precision instruments. Attached Figure Description
[0020] Figure 1 (Al) prepared in Examples 1-2 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 XRD patterns of (X=Cr, In).
[0021] Figure 2 XRD pattern of the bulk sample prepared in Example 1.
[0022] Figure 3 (Al) prepared in Examples 1-2 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 SEM and EDS images of (X=Cr, In).
[0023] Figure 4 (Al) prepared in Examples 1-2 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 The curve showing the relative length of (X=Cr, In) versus temperature.
[0024] Figure 5 Example 1 prepared (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 The TG-DSC curve.
[0025] Figure 6 Example 2 prepared (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 The TG-DSC curve. Detailed Implementation
[0026] To make the present invention clearer and more explicit, the present invention will be further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.
[0027] Example 1
[0028] Solid-phase preparation (Al) 0.2Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 Ceramic powder:
[0029] Al₂O₃, Sc₂O₃, Fe₂O₃, Ga₂O₃, Cr₂O₃, and W₂O₃ were selected as raw materials (each with a mass purity of 99 wt%). The Al₂O₃, Sc₂O₃, Fe₂O₃, Ga₂O₃, Cr₂O₃, and W₂O₃ were then processed according to the target product (Al₂O₃, Sc₂O₃, Fe₂O₃, Ga₂O₃, Cr₂O₃, and W₂O₃). 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 A mixture of Al:Sc:Fe:Ga:Cr:W in a stoichiometric molar ratio of 0.4:0.4:0.4:0.4:0.4:3 was prepared, moistened with anhydrous ethanol, and ground in an agate mortar for 2 h. The resulting powder was then placed in a crucible and calcined in a muffle furnace at a heating rate of 5 °C / min to 700 °C for 10 h. After cooling to room temperature, the powder was removed and ground again. The resulting powder was then pressed at 10 MPa for 2 min to form cylindrical blanks with a diameter of 8 mm and a height of 3 mm. The cylindrical blanks were then placed in a crucible and calcined in a muffle furnace at a heating rate of 5 °C / min to 1100 °C for 10 h. After natural cooling to room temperature, the target product (Al) was obtained. 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 .
[0030] Example 2
[0031] Solid-phase preparation (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 Ceramic powder:
[0032] The difference from Example 1 is that Al2O3, Sc2O3, Fe2O3, Ga2O3, In2O3, and W2O3 were selected as raw materials (each raw material had a mass purity of 99 wt%), and Al2O3, Sc2O3, Fe2O3, Ga2O3, In2O3, and W2O3 were mixed according to the target product (Al 0.2 Sc 0.2 Fe 0.2 Ga 0.2In 0.2 )2W3O 12 The stoichiometric molar ratio of Al∶Sc∶Fe∶Ga∶In∶W = 0.4∶0.4∶0.4∶0.4∶3 was ground and mixed evenly; other aspects were the same as in Example 1.
[0033] Compare with Example 1
[0034] The difference from Example 1 lies in the different raw materials used. Specifically, Al2O3, Lu2O3, Fe2O3, Ga2O3, Cr2O3, and W2O3 are selected as raw materials (each with a purity of 99 wt%). Al2O3, Lu2O3, Fe2O3, Ga2O3, Cr2O3, and W2O3 are then mixed according to the target product (Al... 0.2 Lu 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 A mixture of Al:Lu:Fe:Ga:Cr:W in a stoichiometric molar ratio of 0.4:0.4:0.4:0.4:0.4:3 was prepared, moistened with anhydrous ethanol, and ground in an agate mortar for 2 h. The resulting powder was then placed in a crucible and calcined in a muffle furnace at a heating rate of 5 ℃ / min to 700 ℃ for 10 h. After cooling to room temperature, the powder was removed and ground again. The resulting powder was then pressed at a pressure of 10 MPa for 2 min to form a cylindrical blank with a diameter of 8 mm and a height of 3 mm. The cylindrical blank was then placed in a crucible and calcined in a muffle furnace at a heating rate of 5 ℃ / min to 1100 ℃ for 10 h. After naturally cooling to room temperature in air, a bulk sample was obtained.
[0035] Product characterization and performance testing
[0036] (Al) prepared in Examples 1-2 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 and (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 XRD pattern and Fe2Mo3O of the sample 12 See the standard card (PDF#83-1701). Figure 1 Based on the shape of the diffraction peaks, the prepared high-entropy tungstate is clearly monoclinic (space group P21 / a, No. 14). Furthermore, almost all the peaks in the XRD pattern correspond to Fe2Mo3O.12 (PDF#83-1701). Furthermore, a careful comparison of the diffraction peak angles reveals that they are similar to those of the monoclinic phase Fe2Mo3O. 12 Compared to standard cards, (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 and (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 The XRD pattern of the sample is shifted to the left overall because the diffraction peaks move to lower angles as the lattice parameters increase.
[0037] The XRD pattern of the bulk sample prepared in Example 1 is shown in Figure 1. Figure 2 .Depend on Figure 2 It can be seen that, based on the shape of the diffraction peaks, the XRD pattern of the sample in Comparison Example 1 and Fe2Mo3O 12 Compared to the standard card, multiple impurity peaks appeared (indicated by asterisks), indicating that the single-phase high-entropy solid solution (Al) was not successfully prepared. 0.2 Lu 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 .
[0038] The (Al) prepared in Examples 1-2 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 (a) and (Al 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 (b) SEM and EDS images of the samples are shown in [reference needed]. Figure 3 SEM analysis revealed clear grain boundaries and a size range of 8–15 μm. EDS analysis showed uniform elemental distribution with no elemental enrichment. The XRD and EDS results showed good agreement, indicating that a single-phase solid solution had been successfully prepared.
[0039] The (Al) prepared in Examples 1-2 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr0.2 )2W3O 12 and (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 The curve showing the relative length of the sample (i.e., dL / L0, where dL is the length after expansion minus the length before expansion, i.e., the original length, and L0 is the original length of the product, the same below) versus temperature is shown below. Figure 4 It can be seen that: although (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 and (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 The samples exhibited different coefficients of thermal expansion, but all showed near-zero expansion characteristics within a certain temperature range. Calculations showed that (Al...) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 The coefficient of thermal expansion is 0.90 × 10⁻⁶. -6 K -1 (220~780 ℃), (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 The coefficient of thermal expansion is 0.76 × 10⁻⁶. -6 K -1 (160~780 ℃). Furthermore, the inflection point in the thermal expansion curve indicates the transformation of the two high-entropy solid solutions from a monoclinic phase to an orthorhombic phase. The results show that the (Al) prepared in this invention… 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 and (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12All of them exhibit near-zero expansion characteristics within the temperature range, and the near-zero expansion temperature range is relatively wide, which has high practical significance and application value.
[0040] The (Al) prepared in Examples 1-2 0.2 Sc 0.2 Fe 0.2 Ga 0.2 Cr 0.2 )2W3O 12 and (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 In 0.2 )2W3O 12 The TG-DSC curve of the sample is shown in the figure. Figure 5 and Figure 6 The TG curves show that the samples prepared in this invention do not exhibit significant weight loss within a temperature range of 25–1000 °C, indicating good thermal stability.
Claims
1. A near-zero expansion high-entropy oxide, characterized in that: The molecular formula is (Al) 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 , where X = Cr or In.
2. A method for preparing a near-zero expansion high-entropy oxide as described in claim 1, characterized in that, The preparation steps are as follows: (1) Select Al2O3, Sc2O3, Fe2O3, Ga2O3, X2O3 and W2O3 as raw materials, and mix Al2O3, Sc2O3, Fe2O3, Ga2O3, X2O3 and W2O3 according to the target product (Al 0.2 Sc 0.2 Fe 0.2 Ga 0.2 X 0.2 )2W3O 12 The stoichiometric molar ratio of Al∶Sc∶Fe∶Ga∶X∶W = 0.4∶0.4∶0.4∶0.4∶3 was ground and mixed evenly. (2) The mixed powder obtained in step (1) is directly sent to sintering, sintered at 700~1100 ℃ for 5~10 h, cooled to room temperature and taken out, and then ground again; (3) Press the mixed powder obtained in step (2) into tablets and then send them to sinter. Sinter at 700~1100 ℃ for 5~10 h to obtain the target product.
3. The method for preparing near-zero expansion high-entropy oxides as described in claim 2, characterized in that: In step (1), wet grinding is used. Ethanol is added when grinding the raw materials. The amount added is based on wetting Al2O3, Sc2O3, Fe2O3, Ga2O3, X2O3 and W2O3.
4. The method for preparing near-zero expansion high-entropy oxides as described in claim 2, characterized in that: In step (1), the mass purity of the raw materials Al2O3, Sc2O3, Fe2O3, Ga2O3, X2O3 and W2O3 is 99~99.99%.
5. The method for preparing near-zero expansion high-entropy oxides as described in claim 2, characterized in that: In steps (2) and (3), the heating rate is 5~10 ℃ / min.
6. The method for preparing near-zero expansion high-entropy oxides as described in claim 2, characterized in that: In step (3), the mixed powder is pressed into a cylindrical preform with a diameter of 8-10 mm and a height of 3-6 mm during tableting.
7. The method for preparing near-zero expansion high-entropy oxide as described in claim 2, characterized in that: In step (3), the pressure during tablet compression is 4~10 MPa and the holding time is 2~5 min.