A temperature-stable perovskite structure high-temperature piezoelectric ceramic material and preparation method thereof

Abstract

A temperature-stable perovskite structure high-temperature piezoelectric ceramic material and a preparation method thereof, belonging to the field of piezoelectric ceramic materials. The matrix chemical composition of the ceramic material is xBi(Zn 2 / 3 Nb 1 / 3 )O3‑yBiScO3‑zPbTiO3(0.003≤x≤0.01, 0.35≤y≤0.425, z=1‑x‑y), prepared by high-temperature solid-phase reaction method. The high-temperature piezoelectric ceramic material provided by the present invention has a high Curie temperature, and has high and stable piezoelectric charge coefficient, piezoelectric voltage coefficient and transduction coefficient in a wide temperature range of 50 to 260°C. It can meet the requirements of higher comprehensive piezoelectric parameters of materials, and advanced electromechanical coupling devices such as piezoelectric sensors and piezoelectric energy collectors used in high-temperature fields, and has great engineering application value.

Description

Technical Field

[0001] The present invention belongs to the field of piezoelectric ceramic materials, and in particular relates to a temperature-stable perovskite structure high-temperature piezoelectric ceramic material and a preparation method thereof. Background Art

[0002] Piezoelectric ceramic materials can realize the mutual conversion between mechanical energy and electrical energy, and are the key functional units in various passive electronic components. In recent years, the booming aerospace, oil exploration, nuclear industry and many other fields are in urgent need of high-quality piezoelectric devices such as sensors, energy harvesters, and transducers that can work stably in harsh high-temperature environments to undertake service tasks such as structural health monitoring, wireless power supply, and attitude control. However, the Pb(Zr,Ti)O3-based ceramics that dominate the piezoelectric materials and devices market have a safe operating temperature below 200°C, which is difficult to meet the high-temperature application requirements of the above-mentioned cutting-edge fields. Perovskite-type BiScO3-PbTiO3 (BS-PT) piezoelectric ceramics Curie temperature (T c ~450℃) is nearly 100℃ higher than Pb(Zr,Ti)O3, making it a strong competitor for use in high-temperature environments above 200℃.

[0003] For high temperature piezoelectric applications, piezoelectric ceramics first need to have a high Curie temperature (T c >400℃) to ensure its high temperature application; secondly, it needs to have high voltage electrical properties, that is, high voltage charge coefficient (d 33 ), high voltage voltage coefficient (g 33 ) and high conversion coefficient (d 33 ·g 33 ) to achieve efficient conversion of mechanical energy / electrical energy; in addition, when the ambient temperature changes, in order to ensure the safe and stable operation of the device, the piezoelectric performance needs to maintain excellent stability (fluctuation rate (η) ≤ ± 20%) in a wide temperature range. Taking the piezoelectric performance at 200°C as the benchmark, the temperature change rate (η) of the piezoelectric performance of the material can be expressed as:

[0004]

[0005] Among them, X represents the piezoelectric properties of the material, that is, d 33 , g 33 and d 33 ·g 33 , X T is the piezoelectric property of the material at a certain temperature, X 200℃ is the piezoelectric performance of the material at 200°C.

[0006] The present invention converts Bi(Zn 2 / 3 Nb 1 / 3 )O3(BZN) motif was introduced into the BS-PT matrix to construct xBi(Zn 2 / 3 Nb1 / 3 )O3-yBiScO3-zPbTiO3 (abbreviated as xBZN-yBS-zPT) high temperature piezoelectric ceramic material system. Among them, the best xBZN-yBS-zPT ceramic sample not only has a high Curie temperature (T c =442°C), and has high and stable comprehensive piezoelectric performance (d 33 =558±20%pC / N,g 33 =24.03×10 -3 ±20%Vm / N,d 33 ·g 33 =13409×10 -15 ±20%m 2 / N). The excellent comprehensive piezoelectric performance and temperature stability of the high-temperature piezoelectric ceramic material system in this application have not been reported yet. Summary of the invention

[0007] The purpose of the present invention is to obtain a high-temperature piezoelectric ceramic with excellent comprehensive performance of high Curie temperature, high and thermally stable piezoelectric charge coefficient, piezoelectric voltage coefficient and conversion coefficient and a preparation method thereof, so as to provide material support for the preparation of advanced piezoelectric devices that can stably and efficiently realize electromechanical conversion in a wide temperature range.

[0008] The characteristics of the present invention are that, on the one hand, a combination of strong ferroelectrically active and inexpensive Zn ions and Nb ions is used to replace the weakly ferroelectrically active Sc ions in the BS-PT matrix to enhance the piezoelectric properties of the system; on the other hand, the 4s and 4p orbitals of the Zn ions are hybridized with the 2p orbital of O to form a strong Zn-O covalent bond, while the 4d 0 The empty orbital Nb ions can induce greater distortion of the BO6 octahedron based on the second-order Jahn-Teller effect. The synergistic effect of the two promotes the displacement of the B-site ions and the coupling of the displacement of the A and B-site ions, enhances the lattice distortion, and thus improves the piezoelectric properties and its thermal stability.

[0009] The ceramic material of the present invention is characterized in that xBi(Zn 2 / 3 Nb 1 / 3 )O3-yBiScO3-zPbTiO3 (abbreviated as xBZN-yBS-zPT) 0.003≤x≤0.01, 0.35≤y≤0.425, z is 1-xy. Preferably x=0.003, y=0.372, z=0.625, i.e. 0.003BZN-0.372BS-0.625PT, the Curie temperature of the ceramic sample is T c =442℃, the piezoelectric properties at 200℃ are: piezoelectric charge coefficient d 33=558pC / N, piezoelectric voltage coefficient g 33 =24.03×10 -3 Vm / N, transduction coefficient d 33 ·g 33 =13409×10 -15 m 2 / N, and the change rate η in the temperature range of 50-260℃ does not exceed ±20% (based on η at 200℃), which lays a solid material foundation for the preparation of advanced high-temperature piezoelectric devices.

[0010] The method for preparing the high-temperature piezoelectric ceramic material having a high Curie temperature and high and stable comprehensive piezoelectric performance in a wide temperature range of the present invention is characterized in that the material is prepared by a traditional high-temperature solid-phase reaction method. Specifically, the method comprises the following steps:

[0011] (1) According to xBi(Zn 2 / 3 Nb 1 / 3 )O3-yBiScO3-zPbTiO3 (abbreviated as xBZN-yBS-zPT, 0.003≤x≤0.01, 0.35≤y≤0.425, z=1-xy) Six chemical raw materials of high temperature piezoelectric ceramic material, Bi2O3, Sc2O3, Pb3O4, TiO2, ZnO and Nb2O5, were weighed respectively, put into a ball mill, ball milled for 12h with anhydrous ethanol as the medium, and the ball milled slurry was dried at 100℃~120℃;

[0012] (2) grinding the dried mixture and placing it in an alumina crucible, calcining it at 800-850° C., keeping it warm for 2 hours, and cooling it to room temperature with the furnace; preferably 850° C.;

[0013] (3) adding anhydrous ethanol to the calcined powder for secondary ball milling for 12 h, and drying the ball milled slurry at 100° C. to 120° C.;

[0014] (4) adding a binder to the powder after the secondary ball milling, granulating, sieving, pressing into a ceramic green body, and heating to remove binder;

[0015] If a polyvinyl alcohol (PVA) binder with a mass fraction of 5wt.% is added, the ceramic green body is pressed under a uniaxial pressure of 6-8MPa for 2 minutes, and then subjected to a binder removal treatment at 560°C, kept at this temperature for 3 hours, and cooled to room temperature along with the furnace;

[0016] (5) Sintering the debinding green body at 1100-1150°C, keeping the temperature for 2 hours, and cooling to room temperature with the furnace; preferably 1140°C.

[0017] After sintering, the ceramic samples were polished and infiltrated with silver electrodes, and then polarized at 5 kV / mm for 0.5 h in 120°C silicone oil. After aging at room temperature for 24 h, the electrical properties of the ceramic samples were tested.

[0018] Among them, the best ceramic sample composition of pure perovskite structure is x=0.003, y=0.372, z=0.625, that is, 0.003BZN-0.372BS-0.625PT. After in-situ temperature test, the Curie temperature T c =442℃, the piezoelectric properties at 200℃ are: piezoelectric charge coefficient d 33 =558pC / N, piezoelectric voltage coefficient g 33 =24.03×10 -3 Vm / N, transduction coefficient d 33 ·g 33 =13409×10 -15 m 2 / N, and the change rate η does not exceed ±20% in the temperature range of 50-260℃, which can meet the application requirements of the above-mentioned high-end technology fields for high-temperature piezoelectric devices such as piezoelectric sensors, piezoelectric energy harvesters, and piezoelectric transducers.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The best sample in the present invention has a high Curie temperature, a high and thermally stable piezoelectric charge coefficient, a piezoelectric voltage coefficient and a conversion coefficient, which is beneficial to improving the electromechanical coupling capability of high-temperature piezoelectric devices. It is a very promising perovskite structure piezoelectric ceramic material for high-temperature applications.

[0021] (2) The best sample of the present invention has comprehensive piezoelectric properties, namely, piezoelectric charge coefficient, piezoelectric voltage coefficient and transduction coefficient, and has excellent thermal stability in an ultra-wide temperature range of 50 to 260°C, which is beneficial to improving the service reliability of high-temperature piezoelectric devices and is a very competitive high-temperature piezoelectric ceramic material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 (a) XRD patterns and (b) dielectric temperature spectra of 0.003BZN-0.377BS-0.62PT (abbreviated as 1#), 0.003BZN-0.372BS-0.625PT (abbreviated as 2#), and 0.003BZN-0.367BS-0.63PT (abbreviated as 3#) ceramic samples in the specific implementation of the present invention.

[0023] Figure 2The in-situ temperature-varying (a) piezoelectric charge coefficient d of the ceramic samples 0.003BZN-0.377BS-0.62PT (abbreviated as 1#), 0.003BZN-0.372BS-0.625PT (abbreviated as 2#), and 0.003BZN-0.367BS-0.63PT (abbreviated as 3#) in the specific implementation of the present invention 33 (b) Piezoelectric voltage coefficient g 33 and (c) the conversion coefficient d 33 ·g 33 , the test frequency is 100Hz.

[0024] Figure 3 The in-situ temperature-varying (a) piezoelectric charge coefficient d of the ceramic samples 0.003BZN-0.377BS-0.62PT (abbreviated as 1#), 0.003BZN-0.372BS-0.625PT (abbreviated as 2#), and 0.003BZN-0.367BS-0.63PT (abbreviated as 3#) in the specific implementation of the present invention 33 Temperature change rate, (b) piezoelectric voltage coefficient g 33 The temperature change rate and (c) the energy conversion coefficient d 33 ·g 33 The rate of temperature change. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below through examples, which are only for the purpose of illustration and are not intended to limit the present invention.

[0026] The present invention provides a temperature-stable perovskite structure high-temperature piezoelectric ceramic material, characterized in that its chemical composition is xBi(Zn 2 / 3 Nb 1 / 3)O3-yBiScO3-zPbTiO3 (abbreviated as xBZN-yBS-zPT, 0.003≤x≤0.01, 0.35≤y≤0.425, z=1-xy). The raw materials include: Bi2O3, Sc2O3, Pb3O4, TiO2, ZnO and Nb2O5. The specific preparation method is as follows: first, weigh the raw materials according to the stoichiometric ratio of each component, put them into a ball mill and use anhydrous ethanol as the medium for ball milling for 12 hours; then place the obtained mixture in a 100℃ oven for drying; after grinding, place the dried mixture in a closed alumina crucible and calcine at 850℃, keep it warm for 2 hours, and cool it to room temperature with the furnace; place the obtained calcined product and the ball milling medium anhydrous ethanol in a ball mill for secondary ball milling, the ball milling time is 12 hours, and the ball milling slurry is dried at 100℃; add a binder with a mass fraction of about 5wt.% to the dried powder, granulate, sieve, and press it into a ceramic blank, sinter it at 1140℃ after debinding treatment, keep it warm for 2 hours, and cool it to room temperature with the furnace. The sintered ceramic sample is surface polished, silver electrodes are sintered, and then placed in 120℃ silicone oil for polarization at a voltage of 5kV / mm for 0.5 hours. After aging at room temperature for 24 hours, the electrical properties of the ceramic sample are tested.

[0027] The essential features and significant advantages of the present invention are further illustrated by the following examples. It should be noted that the present invention is by no means limited to the described examples.

[0028] Embodiment 1:

[0029] Bi2O3, Sc2O3, Pb3O4, TiO2, ZnO and Nb2O5 were weighed according to the stoichiometric ratio of 0.003BZN-0.377BS-0.62PT (abbreviated as 1#), and ball-milled for 12 hours with anhydrous ethanol as the medium. The mixture was dried at 100℃ and calcined at 850℃ for 2 hours; anhydrous ethanol was added for secondary ball milling for 12 hours and then dried, and a binder with a mass fraction of about 5wt.% was added. After granulation and sieving, it was pressed into a ceramic blank, sintered at 1140℃ after debinding treatment, kept warm for 2 hours, and cooled to room temperature with the furnace. After sintering, the ceramic sample was polished on the surface and infiltrated with silver electrodes, and then placed in 120℃ silicone oil and polarized at 5kV / mm voltage for 0.5 hours. After aging at room temperature for 24 hours, the electrical properties of the ceramic sample were tested.

[0030] Embodiment 2:

[0031] The preparation of 0.003BZN-0.372BS-0.625PT (abbreviated as 2#) ceramic material is the same as Example 1.

[0032] Embodiment 3:

[0033] The preparation of 0.003BZN-0.367BS-0.63PT (abbreviated as 3#) ceramic material is the same as Example 1.

[0034] Table 1 Performance of the above embodiments

[0035]

Claims

1. A temperature-stable perovskite structure high-temperature piezoelectric ceramic material, characterized in that: The general chemical composition formula is: xBi(Zn 2 / 3 Nb 1 / 3 )O3-yBiScO3-zPbTiO3, x = 0.003, y = 0.372, z = 0.625 ceramic sample has a high Curie temperature of 442 ° C, and the piezoelectric properties at 200 ° C are: piezoelectric charge coefficient d 33 =558pC / N, piezoelectric voltage coefficient g 33 =24.03×10 -3 Vm / N, transduction coefficient d 33 ·g 33 =13409×10 -15 m 2 / N, and the change rate η does not exceed ±20% in the temperature range of 50~260℃.

2. The method for preparing the perovskite structure high temperature piezoelectric ceramic material according to claim 1, characterized in that: Prepared according to the following steps: (1) Weigh the raw materials Bi2O3, Sc2O3, Pb3O4, TiO2, ZnO and Nb2O5 according to the stoichiometric ratio, use anhydrous ethanol as the medium, ball mill in a horizontal ball mill for 12 h, and then dry at 100°C; (2) grinding the dried mixture and placing it in an alumina crucible, calcining it at 850° C., keeping it at that temperature for 2 h, and cooling it to room temperature along with the furnace; (3) adding anhydrous ethanol to the calcined powder for secondary ball milling for 12 h and drying at 100 °C; (4) adding a binder to the powder after the secondary ball milling, granulating, sieving, pressing into a ceramic green body, and heating for debinding treatment; (5) Sintering the green body after debinding treatment at 1140°C, keeping the temperature for 2 hours, and cooling it to room temperature along with the furnace; (6) The obtained ceramic sheet is polished, silver electrodes are sintered, and then artificially polarized to obtain a piezoelectric ceramic material.

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