BaTiO3-based lead-free iron piezoelectric ceramic material and preparation method thereof
By introducing Ta and Sc into the BaTiO3 matrix, a lead-free iron piezoelectric ceramic material with a huge electrocaloric effect across the entire temperature range was prepared. This solved the technical problems of environmental pollution and lead-free systems, and enabled the technical application of lead-free systems. It also solved the technical problems of applicable electric fields, and achieved a huge electrocaloric effect and an ultra-wide operating temperature window for lead-free systems, making them suitable for commercial applications.
Patent Information
- Application Number
- CN202411085941.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-08
- Publication Date
- 2025-12-30
AI Technical Summary
Existing refrigeration technologies rely on refrigerants, which leads to environmental pollution, and lead-free systems are difficult to achieve large caloric effects and wide operating temperature windows at room temperature.
Using Ba0.86Ca0.14Ti1-x(Ta0.5Sc0.5)xO3 ceramic material, a lead-free iron piezoelectric ceramic material with a huge electrocaloric effect across the entire temperature range was prepared by solid-state synthesis, introducing pentavalent Ta and trivalent Sc.
It achieves a large electrocaloric effect and an ultra-wide operating temperature window in a lead-free system, with the applicable electric field increased from 50kV/cm to 180kV/cm and the temperature range from 303-423K, making it suitable for commercial applications.
Smart Images
Figure CN121226005A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of piezoelectric ceramic materials technology, and in particular to a BaTiO3-based lead-free iron piezoelectric ceramic material and its preparation method. Background Technology
[0002] Most current refrigeration technologies rely on traditional vapor compressor refrigeration, which primarily uses refrigerants (Freon, alkanes, ammonia, and carbon dioxide). The use of these refrigerants not only generates large amounts of carbon dioxide, contributing to the greenhouse effect, but also severely damages the ozone layer. Furthermore, while miniaturization of electronic devices is a growing trend, managing the heat generated during operation remains a significant challenge.
[0003] Therefore, it is crucial to find a new, environmentally friendly, and easily miniaturized refrigeration technology to replace traditional solid-state refrigeration technology. Electrocaloric solid-state refrigeration technology has attracted considerable attention due to its large Carnot cycle coefficient (≈65%) and ease of miniaturization.
[0004] Currently, electrocaloric refrigeration technology is still immature, and the electrocaloric effect with excellent performance is concentrated in lead-based systems. However, lead-based systems pose a significant environmental hazard, while lead-free systems struggle to simultaneously achieve both a large electrocaloric effect and a wide operating temperature window at room temperature. The Ba provided by this invention... 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x O3 (0.04≤x≤0.12) ceramic materials exhibit a large electrocaloric effect (ΔT>85%) across the entire temperature range. Summary of the Invention
[0005] The purpose of this invention is to provide a BaTiO3-based lead-free iron piezoelectric ceramic material and its preparation method, addressing the aforementioned problems.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A BaTiO3-based lead-free iron piezoelectric ceramic material, wherein the chemical composition of the ceramic material is Ba 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x O3, where 0.04≤x≤0.12.
[0008] The method for preparing a BaTiO3-based lead-free iron piezoelectric ceramic material includes the following steps:
[0009] (1) Preparation of raw materials: according to the chemical formula Ba 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x The chemical molar ratio of elements in O3 is obtained by using Ba, Ca, Ti, Ta, and Sc sources as raw materials;
[0010] (2) One-time ball milling: The raw materials are mixed and added into the milling jar, using zirconium dioxide balls as the ball milling medium and ethanol as the ball milling solvent, and ball milling at a speed of 380-500 rpm for 8-12 hours, and then dried to obtain mixed powder A;
[0011] (3) Pre-calcination of raw materials: Place the mixed powder A obtained in step (2) in an alumina crucible and pre-calcine it at 950-1000℃ for 4-6 hours to obtain mixed powder B;
[0012] (4) Secondary ball milling: The mixed powder B is placed in a ball milling jar for secondary ball milling to obtain mixed powder C;
[0013] (5) Tableting: The mixed powder C is pressed to obtain sample A, and sample A is subjected to cold isostatic pressing to obtain sample B;
[0014] (6) Sintering: Sample B is sintered in an oxygen atmosphere at a temperature of 1280-1300℃ for 2-3 hours to obtain sample C;
[0015] (7) Polish the sample C obtained in step (6), coat both sides of the sample C with silver electrodes, and then keep it at 630-650℃ for 20-30 minutes to obtain the final sample Ba. 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x O3 ceramic materials.
[0016] Preferably, in the above preparation method, the Ba source, Ti source, Ca source, Ta source and Sc source mentioned in step (1) are their respective salts or oxides.
[0017] Preferably, in the above preparation method, the Ba source in step (1) is barium titanate, the Ti source is titanium dioxide, the Ca source is calcium carbonate, the Ta source is tantalum pentoxide, and the Sc source is scandium trioxide.
[0018] Preferably, in the above preparation method, the drying conditions in step (2) are: drying at 100-120°C for 1-2 hours.
[0019] Preferably, in the above preparation method, the ball milling conditions in step (4) are the same as those in step (2).
[0020] Preferably, in the above preparation method, the sample A in step (5) is a circular sample with a diameter of 8 mm and a thickness of 1.2 mm.
[0021] Preferably, in the above preparation method, the specific steps of the cold isostatic pressing treatment in step (5) are as follows: wrap sample A with a rubber product and put it into the cold isostatic hydraulic oil, and keep it under pressure of 200-250 MPa for 8-10 minutes.
[0022] Preferably, in the above preparation method, the heating rate of calcination in step (6) is: 3℃ / min when the temperature is below 1000℃, and 1.5℃ / min when the temperature is above 1000℃; the heating rate of heat preservation in step (7) is 1 to 1.5℃ / min.
[0023] Preferably, in the above preparation method, the diameter of the silver electrode in step (7) is 2 mm.
[0024] In summary, due to the adoption of the above technical solution, the present invention has the following beneficial effects:
[0025] This invention uses Ba 0.86 Ca 0.14 Using TiO3 as a matrix, pentavalent Ta and trivalent Sc were introduced, and ceramic materials were synthesized via a solid-state method, ultimately yielding Ba ceramic material with a large electrocaloric effect across the entire temperature range. 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x O3, where x ranges from 0.04 to 0.12, not only shifts the Curie temperature towards room temperature but also increases relaxation, which is beneficial for achieving an ultra-wide electrocaloric operating temperature window at room temperature. Within the temperature range of 303-423 K, the maximum applicable electric field increases from 50 kV / cm to 180 kV / cm. Furthermore, the introduction of Ta+Sc helps maintain the overall ferroelectricity of the matrix, facilitating a larger electrocaloric effect at room temperature, achieving both a 1.51 K electrocaloric effect and an ultra-wide operating temperature range of 120 K. Therefore, the ceramic material prepared by the method provided in this invention achieves the coexistence of a large electrocaloric effect and an ultra-wide operating temperature window in a lead-free system, and holds promise for the commercial application of lead-free electrocaloric materials. Attached Figure Description
[0026] Figure 1In the image, (a) shows the XRD patterns of the ceramic samples prepared in Examples 1-5; (b) shows the magnified images within the range of 2θ = 44.7-46°.
[0027] Figure 2 The graphs show the PE cycling, polarization, and temperature variation curves of the ceramic samples prepared in Examples 1-5; where (a) represents the PE cycling measured in the temperature range of 303-423 K; and (b) represents... (c) shows the functional relationship between the curve and temperature; (d) shows the functional relationship between ΔT and temperature change. Detailed Implementation
[0028] To more clearly illustrate the present invention, the following specific embodiments will be used to further explain the invention.
[0029] I. Preparation Examples
[0030] Example 1
[0031] A method for preparing a BaTiO3-based lead-free iron piezoelectric ceramic material includes the following steps:
[0032] (1) Preparation of raw materials: according to the chemical formula Ba 0.86 Ca 0.14 Ti 0.96 (Ta 0.5 Sc 0.5 ) 0.04 The chemical molar ratio of elements in O3 is determined by using barium titanate, titanium dioxide, calcium carbonate, tantalum pentoxide, and scandium trioxide as raw materials.
[0033] (2) One-time ball milling: The raw materials are mixed and added into the milling jar, using zirconia balls as the ball milling medium and ethanol as the ball milling solvent. The mixture is ball milled at 380 rpm for 12 hours, then poured into a petri dish and placed in a 120℃ drying oven to dry for 1 hour to obtain mixed powder A.
[0034] (3) Pre-calcination of raw materials: The mixed powder A obtained in step (2) is placed in an alumina crucible and pre-calcined at 950°C for 6 hours to obtain mixed powder B, which is the powder with carbides removed and the main crystal phase initially formed.
[0035] (4) Secondary ball milling: Place the mixed powder B in a ball milling jar, use zirconium dioxide balls as the ball milling medium and ethanol as the ball milling solvent, and ball mill at a speed of 380 rpm for 12 hours to obtain mixed powder C;
[0036] (5) Compressing: Compress the mixed powder C into a circular sample with a diameter of 8 mm and a thickness of 1.2 mm, and denoted as sample A. Wrap sample A with a rubber product and place it in cold isostatic hydraulic oil. Hold it under pressure of 200 MPa for 10 minutes and take it out to obtain sample B.
[0037] (6) Sintering: Place sample B in an alumina crucible and place it in a tube furnace. Sinter at 1280℃ for 3 hours in an oxygen atmosphere. When the temperature is below 1000℃, the temperature is increased at a rate of 3℃ / min. When the temperature is above 1000℃, the temperature is increased at a rate of 1.5℃ / min to obtain sample C.
[0038] (7) Polish the sample C obtained in step (6), coat both sides of the sample C with silver electrodes of 2 mm diameter, and then place it in a tube furnace and heat it to 630°C at a heating rate of 1.5°C / min. Hold it at 630°C for 30 minutes to obtain the final sample Ba. 0.86 Ca 0.14 Ti 0.96 (Ta 0.5 Sc 0.5 ) 0.04 O3 ceramic materials.
[0039] Example 2
[0040] A method for preparing a BaTiO3-based lead-free iron piezoelectric ceramic material includes the following steps:
[0041] (1) Preparation of raw materials: according to the chemical formula Ba 0.86 Ca 0.14 Ti 0.94 (Ta 0.5 Sc 0.5 ) 0.06 The chemical molar ratio of elements in O3 is determined by using barium titanate, titanium dioxide, calcium carbonate, tantalum pentoxide, and scandium trioxide as raw materials.
[0042] (2) One-time ball milling: The raw materials are mixed and added into the milling jar, using zirconia balls as the ball milling medium and ethanol as the ball milling solvent. The mixture is ball milled at 500 rpm for 8 hours, then poured into a petri dish and placed in a 100℃ drying oven to dry for 2 hours to obtain mixed powder A.
[0043] (3) Pre-calcination of raw materials: The mixed powder A obtained in step (2) is placed in an alumina crucible and pre-calcined at 1000℃ for 4 hours to obtain mixed powder B, which is the powder with carbides removed and the main crystal phase initially formed.
[0044] (4) Secondary ball milling: Place the mixed powder B in a ball milling jar, use zirconia balls as the ball milling medium and ethanol as the ball milling solvent, and ball mill at a speed of 500 rpm for 8 hours to obtain mixed powder C;
[0045] (5) Compressing: Compress the mixed powder C into a circular sample with a diameter of 8 mm and a thickness of 1.2 mm, and denoted as sample A. Wrap sample A with a rubber product and place it in cold isostatic hydraulic oil. Hold it under pressure of 250 MPa for 8 minutes and take it out to obtain sample B.
[0046] (6) Sintering: Place sample B in an alumina crucible and put it into a tube furnace. Under an oxygen atmosphere, sinter at 1300℃ for 2 hours. When the temperature is below 1000℃, the temperature is increased at a rate of 3℃ / min. When the temperature is above 1000℃, the temperature is increased at a rate of 1.5℃ / min to obtain sample C.
[0047] (7) Polish the sample C obtained in step (6), coat both sides of the sample C with silver electrodes of 2 mm diameter, and then place it in a tube furnace and heat it to 650°C at a heating rate of 1.5°C / min. Hold it at 650°C for 20 minutes to obtain the final sample Ba. 0.86 Ca 0.14 Ti 0.94 (Ta 0.5 Sc 0.5 ) 0.06 O3 ceramic materials.
[0048] Example 3
[0049] The difference between this embodiment and Embodiment 1 is that the chemical formula of the BaTiO3-based lead-free iron piezoelectric ceramic material is Ba. 0.86 Ca 0.14 Ti 0.92 (Ta 0.5 Sc 0.5 ) 0.08 O3, accordingly, the raw materials in step (1) are weighed according to the chemical formula, and the other steps are the same as in Example 1.
[0050] Example 4
[0051] The difference between this embodiment and Embodiment 1 is that the chemical formula of the BaTiO3-based lead-free iron piezoelectric ceramic material is Ba. 0.86 Ca 0.14 Ti 0.9 (Ta 0.5 Sc 0.5 ) 0.1 O3, accordingly, the raw materials in step (1) are weighed according to the chemical formula, and the other steps are the same as in Example 1.
[0052] Example 5
[0053] The difference between this embodiment and Embodiment 1 is that the chemical formula of the BaTiO3-based lead-free iron piezoelectric ceramic material is Ba. 0.86 Ca 0.14 Ti0.88 (Ta 0.5 Sc 0.5 ) 00.12 O3, accordingly, the raw materials in step (1) are weighed according to the chemical formula, and the other steps are the same as in Example 1.
[0054] II. Performance Testing
[0055] 1. Identification of the compound
[0056] Figure 1 (a) shows the XRD patterns of the ceramic samples prepared in Examples 1-5. Figure 1 As can be seen in (a), all XRD patterns show a single perovskite crystal structure, and no impurity phases were detected. Figure 1 (b) shows the XRD pattern in the range of 2θ = 44.7–46°. It can be observed that at x = 0.04, the diffraction peak near 2θ = 45° splits into two diffraction peaks, (002) and (200), indicating the coexistence of the tetragonal and pseudocubic phases. When x increases to 0.06, the (002) and (200) diffraction peaks merge into a single (002) diffraction peak, indicating that the tetragonal phase evolves towards the pseudocubic phase with increasing doping concentration. Furthermore, with increasing x, the (200) diffraction peak shifts to lower angles. This is because (Ta1 / 2Sc1 / 2) 4+ ionic radius Compare Ba's large ionic radius leads to lattice expansion upon substitution. Ultimately, with increasing doping content, the (200) diffraction peak shifts to lower angles. In summary, this invention successfully synthesizes Ba. 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x Pure phase structure of O3 (x = 0.04, 0.06, 0.08, 0.10 and 0.12) ceramics.
[0057] 2. Electrocardiogram effect test
[0058] The ceramic samples prepared in Examples 1-5 have the general chemical formula Ba. 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x The values of x in O3 are 0.04, 0.06, 0.08, 0.10, and 0.12, respectively. In the following text, x = 0.04, 0.06, 0.08, 0.10, and 0.12 refer to the ceramic samples prepared in Examples 1, 2, 3, 4, and 5, respectively.
[0059] The hysteresis loops for x = 0.04, 0.06, 0.08, 0.10, and 0.12 were measured in the temperature range of 303-423 K, and the results are as follows: Figure 2 As shown in (a). By Figure 2 (a) It can be seen that the maximum applicable electric field increases with the increase of Ta+Sc doping level, from 50 kV / cm at x = 0.04 to 180 kV / cm at x = 0.12; at the same time, spontaneous polarization gradually weakens with the change of temperature.
[0060] Each sample The functional relationship between the curve and temperature is as follows: Figure 2 As shown in (b). Figure 2 (b) It can be seen that there is a significant broad peak in the x = 0.04 component. As the Ta+Sc doping amount increases, the peak becomes wider and more obvious, which is beneficial for achieving a wider operating temperature range.
[0061] Subsequently, the adiabatic temperature change ΔT and the ΔT-T curves for x = 0.04, 0.06, 0.1, and 0.12 were calculated, as follows: Figure 2 As shown in (c). Figure 2 The ΔT-T curve in (c) shows that in the Ta+Sc co-doped BCT ceramic sample, the increase of Ta+Sc doping amount is beneficial to the enhancement of electrocaloric effect. The best electrocaloric performance is achieved at the doping level of x = 0.08, while achieving an electrocaloric effect of 1.51K and an ultra-wide operating temperature range of 120K.
[0062] In summary, this invention achieves the coexistence of a large lead-free battery and an ultra-wide operating temperature window by doping Ta and Sc into a lead-free barium titanate system, which holds promise for the commercial application of lead-free battery materials.
[0063] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.
Claims
1. A BaTiO3-based lead-free iron piezoelectric ceramic material, characterized in that, The chemical composition of the ceramic material is Ba. 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x O3, where 0.04≤x≤0.
12.
2. A method for preparing a BaTiO3-based lead-free iron piezoelectric ceramic material according to claim 1, characterized in that, Includes the following steps: (1) Preparation of raw materials: according to the chemical formula Ba 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x The chemical molar ratio of elements in O3 is obtained by using Ba, Ca, Ti, Ta, and Sc sources as raw materials; (2) One-time ball milling: The raw materials are mixed and added into the milling jar, using zirconium dioxide balls as the ball milling medium and ethanol as the ball milling solvent, and ball milling at a speed of 380-500 rpm for 8-12 hours, and then dried to obtain mixed powder A; (3) Pre-calcination of raw materials: Place the mixed powder A obtained in step (2) in an alumina crucible and pre-calcine it at 950-1000℃ for 4-6 hours to obtain mixed powder B; (4) Secondary ball milling: The mixed powder B is placed in a ball milling jar for secondary ball milling to obtain mixed powder C; (5) Tableting: The mixed powder C is pressed to obtain sample A, and sample A is subjected to cold isostatic pressing to obtain sample B; (6) Sintering: Sample B is sintered in an oxygen atmosphere at a temperature of 1280-1300℃ for 2-3 hours to obtain sample C; (7) Polish the sample C obtained in step (6), coat both sides of the sample C with silver electrodes, and then keep it at 630-650℃ for 20-30 minutes to obtain the final sample Ba. 0.86 Ca 0.14 Ti 1-x (Ta 0.5 Sc 0.5 ) x O3 ceramic materials.
3. The preparation method according to claim 2, characterized in that, The Ba source, Ti source, Ca source, Ta source, and Sc source mentioned in step (1) are their respective salts or oxides.
4. The preparation method according to claim 2, characterized in that: In step (1), the Ba source is barium titanate, the Ti source is titanium dioxide, the Ca source is calcium carbonate, the Ta source is tantalum pentoxide, and the Sc source is scandium trioxide.
5. The preparation method according to claim 2, characterized in that, The drying conditions in step (2) are: drying at 100-120℃ for 1-2 hours.
6. The preparation method according to claim 2, characterized in that, The ball milling conditions in step (4) are the same as in step (2).
7. The preparation method according to claim 2, characterized in that, The sample A mentioned in step (5) is a circular sample with a diameter of 8 mm and a thickness of 1.2 mm.
8. The preparation method according to claim 2, characterized in that, The specific steps of the cold isostatic pressing treatment in step (5) are as follows: wrap sample A with rubber products and put it into the cold isostatic hydraulic oil, and hold it under pressure of 200-250 MPa for 8-10 minutes.
9. The preparation method according to claim 2, characterized in that, The heating rate for calcination in step (6) is 3℃ / minute when the temperature is below 1000℃ and 1.5℃ / minute when the temperature is above 1000℃; the heating rate for heat preservation in step (7) is 1~1.5℃ / minute.
10. The preparation method according to claim 2, characterized in that, The diameter of the silver electrode mentioned in step (7) is 2 mm.