Bismuth layered composite piezoelectric ceramic material as well as preparation method and application thereof

Abstract

The invention discloses a bismuth layered composite piezoelectric ceramic material and a preparation method and application thereof. According to the piezoelectric ceramic material, samarium ions are doped at the A site of Bi4Ti3O12-based ceramic, tungsten, nickel and niobium ion groups are doped at the B site of Bi3TiNbO9-based ceramic, and the Bi4Ti3O12-based ceramic and the Bi3TiNbO9-based ceramic are compounded; the chemical general formula of the material is (1-x) SeyBi4-yTi3O12-xBi3Ti1-Z (W1 / 5Ni2 / 5Nb2 / 5) ZNbO9, 0 < x < = 0.3, 0 < y < = 0.2, and 0 < z < = 0.5. According to the piezoelectric ceramic material, the piezoelectric constant and the high-temperature resistivity of the piezoelectric ceramic material are greatly improved on the premise that the high Curie temperature of BIT-based ceramic is kept, so that the requirements of a high-end high-temperature piezoelectric sensor are met.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric ceramics, and particularly relates to a bismuth-layered composite piezoelectric ceramic material, a preparation method thereof, and an application thereof. Background Art

[0002] Piezoelectric materials can achieve the conversion of mechanical and electrical properties and are widely used in electronic devices. As an indispensable part of many electronic devices, piezoelectric materials usually need to work in extremely harsh high-temperature environments, such as aerospace, geological exploration, power generation industries, etc. As an important family of piezoelectric materials, ferroelectric polycrystalline piezoelectric ceramics are usually the research focus to meet the functions and stability under high-temperature conditions. Ferroelectric ceramics with the perovskite ABO3 structure, such as BaTiO3, Pb(Zr,Ti)O3, Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3, usually have a high piezoelectric constant d 33 (150 - 1500 pC / N), but their Curie temperature is relatively low (100 - 400 °C). Therefore, the operating temperature of this system of ceramics is limited to below 300 °C. Bismuth-layered structured ferroelectric ceramics (BLSFs) have the chemical formula (Bi2O2) 2+ (A m-1 B m O 3m+1 ) 2- , and its structure is along the c-axis direction, and the perovskite-like (A m-1 B m O 3m+1 ) 2- layers are sandwiched between the (Bi2O2) 2+ layers. Usually, BLSFs piezoelectric ceramics have a high Curie temperature T c (500 - 1000 °C), a high mechanical quality factor, and a low aging rate, making them ideal candidates for the high-temperature electronics industry.

[0003] Although bismuth-layered structured ferroelectrics have a very high Curie temperature (T c ), thermal stability, and low dielectric loss, and are widely used in high-temperature fields, their relatively high coercive field and anisotropic structure result in a small piezoelectric constant d 33 . For example, bismuth titanate Bi4Ti3O 12 (abbreviation: BIT)-based ceramics are 3-layer bismuth-layered structured ceramics, and are used as excellent high-temperature piezoelectric materials due to their high Curie point (675 °C). However, due to factors such as strong anisotropy, large coercive field, and large leakage current, the piezoelectric constant is low (d 33 = 8 pC / N), and the high-temperature resistivity is low (5×10 5 Ω·cm@500 °C), and the poor piezoelectric properties limit its application in high-level devices.

[0004] Therefore, on the premise of maintaining a relatively high Curie temperature, the piezoelectric properties and high-temperature resistivity of bismuth titanate-based piezoelectric ceramic materials still need to be further improved. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and propose a bismuth-layered composite piezoelectric ceramic material, its preparation method and application. This bismuth-layered composite piezoelectric ceramic material significantly improves its piezoelectric constant and high-temperature resistivity while maintaining a relatively high Curie temperature to meet the requirements of high-end high-temperature piezoelectric sensors.

[0006] To solve the above problems, an embodiment of the present invention proposes a bismuth-layered composite piezoelectric ceramic material in the first aspect. Samarium ions are doped at the A-site of the Bi4Ti3O 12 -based ceramic, and tungsten, nickel, and niobium ion groups are doped at the B-site of the Bi3TiNbO9-based ceramic. Moreover, the Bi4Ti3O 12 -based ceramic is compounded with the Bi3TiNbO9-based ceramic;

[0007] Its chemical general formula is (1 - x)Sm y Bi 4-y Ti3O 12 - xBi3Ti 1-Z (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) Z NbO9, where 0 < x ≤ 0.3, 0 < y ≤ 0.2, 0 < z ≤ 0.5.

[0008] According to an embodiment of the present invention, a bismuth-layered composite piezoelectric ceramic material is prepared by doping samarium (Sm 3+ ) at the A-site of the BIT-based ceramic and doping tungsten, niobium, and nickel ion groups (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 4+ at the B-site of the Bi3TiNbO9-based ceramic, and compounding the two modified BIT-based ceramics with the Bi3TiNbO9-based ceramic. These three methods improve the performance of the BIT-based piezoelectric ceramics. Co-doping at the A and B sites can better exert the advantages of multi-component composite doping modification. The prepared BIT-based ceramic has the advantages of a large piezoelectric constant, a high Curie temperature, and a high high-temperature resistivity. The piezoelectric constant d 33 of the BIT-based ceramic is increased from 8 pC / N to 26.6 pC / N, and the high-temperature resistivity is increased from 5×10 5 Ω·cm@500 °C to 1.3×10 7 Ω·cm@500 °C to meet the requirements of high-end high-temperature piezoelectric sensors.

[0009] In a second aspect, an embodiment of the present invention provides a method for preparing the above-mentioned bismuth-layered composite piezoelectric ceramic material, comprising the following steps:

[0010] Step 1: Weigh the raw materials for forming Sm y Bi 4-y Ti3O 12 ceramic powder according to stoichiometry, mix them into a slurry, dry the slurry, and pre-sinter to obtain a first powder; Weigh the raw materials for forming Bi3Ti 1-Z (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) Z NbO9 ceramic powder according to stoichiometry, mix them into a slurry, dry the slurry, and pre-sinter to obtain a second powder;

[0011] Step 2: Perform secondary ball milling on the first powder and the second powder according to the ratio of (1-x):x, dry them to obtain a third powder, then add a binder to the third powder, grind and granulate, screen, and press into a shape to obtain a thin circular blank;

[0012] Step 3: Remove the binder from the thin circular blank and sinter to obtain a sintered ceramic sheet;

[0013] Step 4: Polish both sides of the sintered ceramic sheet, print electrodes on it, sinter the electrodes, place it in silicone oil, apply a voltage for polarization to obtain the bismuth-layered composite piezoelectric ceramic material.

[0014] According to the embodiment of the present invention, this method can be prepared by the traditional solid-phase reaction method. The preparation process is simple and stable, easy to operate, suitable for large-scale industrial production promotion, and has practical application value in the field of high-temperature piezoelectric sensors; by using specific polarization temperature and polarization electric field, doping and modifying the BIT-based ceramic material, the polarization is sufficient and the piezoelectric performance is fully developed.

[0015] Optionally, in step 1, the raw materials for forming Sm y Bi 4-y Ti3O 12 ceramic powder include Sm2O3, Bi2O3 and TiO2 titanium source; the raw materials for forming Bi3Ti 1-Z (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) Z NbO9 ceramic powder include TiO2, Nb2O5, Bi2O3, WO3 and NiO.

[0016] Optionally, in step 1, during mixing, using absolute ethanol as the dispersion medium, mix for 4 h to 8 h using a planetary mill at a rotation speed of 150 rpm to 300 rpm; during drying, dry the slurry at a temperature of 110°C to 130°C; during pre-sintering, pre-sinter at a temperature of 700°C to 850°C with a heating rate of 2°C / min to 3°C / min and hold for 3 h to 6 h to obtain the first powder or the second powder.

[0017] Optionally, in step 2, the conditions for secondary ball milling are 200 r / min and the time is 6 h, and the drying temperature is 110°C to 130°C.

[0018] Optionally, in step 2, the binder is an aqueous PVA solution with a concentration of 8 wt%, and the aqueous PVA solution accounts for 12% of the mass of the third powder.

[0019] Optionally, in step 3, debinding is to discharge the binder by holding at 600°C to 850°C for 1 h; sintering is to sinter the thin round blank at 1060°C to 1120°C for 2 h to 4 h with a heating rate not higher than 5°C / min.

[0020] Optionally, in step 4, print platinum / gold electrodes on the sintered ceramic sheet polished on both sides, and then sinter the electrodes at a temperature of 900°C to 1000°C and hold for 10 min to 30 min.

[0021] Optionally, in step 4, apply a DC electric field of 10 kV / mm to 14 kV / mm in silicone oil at 200°C to 220°C and hold for 20 min to 40 min.

[0022] In a third aspect, an embodiment of the present invention provides a piezoelectric device, including the above-mentioned bismuth-layered composite piezoelectric ceramic material or the bismuth-layered composite piezoelectric ceramic material prepared according to the above-mentioned preparation method.

[0023] According to the piezoelectric device of the embodiment of the present invention, using the piezoelectric ceramic material of chemical formula (1-x)Sm y Bi 4-y Ti3O 12 -xBi3Ti 1-Z (W 1 / 5Ni 2 / 5 Nb 2 / 5 ) Z NbO9 to prepare a piezoelectric device can make the piezoelectric device applicable to high-temperature fields.

[0024] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0025] Figure 1 Curie temperature diagram of the bismuth-layered composite piezoelectric ceramic material according to Embodiment 1 and Embodiment 2 of the present invention;

[0026] Figure 2 For the piezoelectric ceramic material d according to the embodiments and comparative examples of the present invention 33 Value variation diagram with depolarization temperature. Detailed implementation mode

[0027] The technical solution of the present invention is described below through specific specific examples. It should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps or that other method steps can be inserted between these clearly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Moreover, unless otherwise stated, the numbers of the method steps are only convenient tools for identifying the method steps, rather than limiting the arrangement order of the method steps or the scope in which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope in which the present invention can be implemented.

[0028] In order to better understand the above technical solution, the exemplary embodiments of the present invention are described in more detail below. Although the exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully communicated to those skilled in the art.

[0029] The test materials used in the present invention are all ordinary commercially available products and can be purchased on the market.

[0030] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0031] Embodiment 1

[0032] The chemical general formula of the bismuth-layered composite piezoelectric ceramic material is (1 - x)Sm y Bi 4-y Ti3O 12 -xBi3Ti 1-Z (W 1 / 5 Ni 2 / 5Nb 2 / 5 ) Z Nb O9, where x = 0.1, y = 0.2, z = 0.5.

[0033] Preparation of the bismuth-layered composite piezoelectric ceramic material:

[0034] Step 1. Preparation of ceramic powder by solid-phase method

[0035] According to the stoichiometric ratio of Sm 0.2 Bi 3.8 Ti3O 12 (i.e., y = 0.2), weigh out the raw materials of Sm2O3 samarium source, Bi2O3 bismuth source, and TiO2 titanium source, all with analytical purity. Put the weighed raw materials into a nylon ball milling tank, use anhydrous ethanol as the dispersion medium, and the mass ratio of it to the total mass of the raw materials is 1:0.8. Use a planetary mill to mix for 8 h at a rotation speed of 150 rpm. Place the slurry in an oven at 130 °C for drying, and then pre-burn at 800 °C with a heating rate of 3 °C / min and hold for 4 h to obtain the first powder.

[0036] According to the stoichiometric ratio of Bi3Ti 0.5 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.5 NbO9 (i.e., z = 0.5), weigh out the raw materials of TiO2 titanium source, Nb2O5 niobium source, Bi2O3 bismuth source, WO3 tungsten source, and NiO nickel source, all with analytical purity. Put the weighed raw materials into a nylon ball milling tank, use anhydrous ethanol as the dispersion medium, and the mass ratio of it to the total mass of the raw materials is 1:0.8. Use a planetary mill to mix for 4 h at a rotation speed of 150 rpm. Place the slurry in an oven at 130 °C for drying, and then pre-burn at 850 °C with a heating rate of 3 °C / min and hold for 3 h to obtain the second powder.

[0037] Step 2: Ball milling, granulation, and forming

[0038] Mix the above-mentioned first powder Sm 0.2 Bi 3.8 Ti3O 12 and the second powder Bi3Ti 0.5 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.5 NbO9 according to the ratio of 9:1 (i.e., x = 0.1) for batching. Then use a planetary ball mill with agate balls and anhydrous ethanol as the medium for secondary ball milling. The mass ratio of anhydrous ethanol to the total mass of the raw materials is 1:0.8, the condition is 200 r / min, and the time is 6 h. Then dry at 110 °C to obtain the third powder after secondary ball milling. Add an 8 wt% aqueous PVA solution as a binder, and the addition amount is 12% of the mass of the third powder. Grind evenly, pass through a 60-mesh sieve, and press into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0039] Step 3: Debinding, sintering

[0040] The thin circular green body is kept at 850 °C for 1 h to discharge the PVA solution, obtaining a ceramic green body; then the ceramic green body is sintered at 1120 °C for 4 h to prepare a sintered ceramic sheet, and the heating rate is not higher than 5 °C / min.

[0041] Step 4: Electrode and polarization

[0042] Both sides of the sintered ceramic sheet after sintering are polished to a thickness of 0.6 mm, platinum / gold electrodes are printed, and then it is kept at 1000 °C for 10 min to complete the firing of the electrodes. Polarization is carried out by applying a DC electric field of 14 kV / mm in silicone oil at 220 °C for 40 min.

[0043] Example 2

[0044] The chemical general formula of the bismuth-layered composite piezoelectric ceramic material is (1-x)Sm y Bi 4-y Ti3O 12 -xBi3Ti 1-Z (W 1 / 5 Ni 2 / 5Nb 2 / 5 ) Z Nb O9, where x = 0.2, y = 0.2, and z = 0.5.

[0045] Preparation of the bismuth-layered composite piezoelectric ceramic material:

[0046] Step 1: Preparation of ceramic powder by solid-phase method

[0047] According to the stoichiometric ratio of Sm 0.2 Bi 3.8 Ti3O 12 (i.e., y = 0.2), weigh the raw materials of Sm2O3 samarium source, Bi2O3 bismuth source, and TiO2 titanium source, and their purities are all analytical pure. Put the weighed raw materials into a nylon ball milling tank, use anhydrous ethanol as the dispersion medium, and its mass ratio to the total mass of the raw materials is 1:0.8. Use a planetary mill to mix for 4 h at a rotation speed of 300 rpm. Place the slurry in an oven at 110 °C to dry, and then pre-burn at 700 °C with a heating rate of 2 °C / min and keep warm for 3 h to obtain the first powder.

[0048] According to Bi3Ti 0.5 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.5For the stoichiometric ratio of NbO9 (i.e., z = 0.5), weigh the raw materials of TiO2 titanium source, Nb2O5 niobium source, Bi2O3 bismuth source, WO3 tungsten source, and NiO nickel source, all with an analytical purity. Put the weighed raw materials into a nylon ball milling tank, use anhydrous ethanol as the dispersion medium, with a mass ratio of 1:0.8 to the total mass of the raw materials, and use a planetary mill to mix for 4 h at a speed of 150 rpm. Place the slurry in an oven at 110 °C to dry, and then pre-burn at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the second powder.

[0049] Step 2: Ball milling, granulation, and forming

[0050] Mix the above-mentioned first powder Sm 0.2 Bi 3.8 Ti3O 12 and the second powder Bi3Ti 0.5 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.5 NbO9 in a ratio of 8:2 (i.e., x = 0.2) for batching. Then use a planetary ball mill with agate balls and anhydrous ethanol as the medium for secondary ball milling. The mass ratio of anhydrous ethanol to the total mass of the raw materials is 1:0.8, the condition is 200 r / min, and the time is 6 h. Then dry at 110 °C to obtain the third powder after secondary ball milling. Add an 8 wt% aqueous PVA solution as a binder, with an addition amount in a mass ratio of 12% to the third powder. Grind evenly, pass through a 60-mesh sieve, and then press into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0051] Step 3: Debinding, sintering

[0052] The thin circular blank is kept at 600 °C for 1 h to discharge the PVA solution to obtain a ceramic green body; then the ceramic green body is sintered at 1120 °C for 4 h to obtain a sintered ceramic sheet, with a heating rate not higher than 5 °C / min.

[0053] Step 4: Electroding, poling

[0054] The two sides of the sintered ceramic sheet after sintering are polished to a thickness of 0.6 mm, printed with platinum / gold electrodes, and then kept at 950 °C for 10 min to complete the firing of the electrodes. Apply a DC electric field of 12 kV / mm in 220 °C silicone oil and hold for 30 min for poling.

[0055] Example 3

[0056] The chemical general formula of the bismuth-layered composite piezoelectric ceramic material is (1 - x)Sm y Bi 4-y Ti3O 12 -xBi3Ti 1-Z (W1 / 5 Ni 2 / 5Nb 2 / 5 ) Z NbO9, where x = 0.3, y = 0.3, and z = 0.5.

[0057] Preparation of bismuth layer-structured composite piezoelectric ceramic material:

[0058] Step 1. Preparation of ceramic powder by solid-phase method

[0059] According to the stoichiometric ratio of Sm 0.3 Bi 3.7 Ti3O 12 (i.e., y = 0.3), weigh the raw materials of Sm2O3 samarium source, Bi2O3 bismuth source, and TiO2 titanium source, all with analytical purity. Put the weighed raw materials into a nylon ball-milling tank, use absolute ethanol as the dispersion medium, with a mass ratio of 1:0.8 to the total mass of the raw materials, mix for 8 h using a planetary mill at a rotation speed of 250 rpm, place the slurry in an oven at 120 °C for drying, and then pre-burn at 800 °C with a heating rate of 3 °C / min and hold for 6 h to obtain the first powder.

[0060] According to the stoichiometric ratio of Bi3Ti 0.5 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.5 NbO9 (i.e., z = 0.5), weigh the raw materials of TiO2 titanium source, Nb2O5 niobium source, Bi2O3 bismuth source, WO3 tungsten source, and NiO nickel source, all with analytical purity. Put the weighed raw materials into a nylon ball-milling tank, use absolute ethanol as the dispersion medium, with a mass ratio of 1:0.8 to the total mass of the raw materials, mix for 8 h using a planetary mill at a rotation speed of 150 rpm, place the slurry in an oven at 130 °C for drying, and then pre-burn at 850 °C with a heating rate of 3 °C / min and hold for 6 h to obtain the second powder.

[0061] Step 2. Ball milling, granulation, and forming

[0062] Mix the above-mentioned first powder Sm 0.3 Bi 3.7 Ti3O 12 and the second powder Bi3Ti 0.5 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.5NbO9 was proportioned according to a ratio of 7:3 (i.e., x = 0.3), and then planetary ball milling was carried out twice using agate balls and absolute ethanol as the medium. The mass ratio of absolute ethanol to the total mass of raw materials was 1:0.8, the condition was 200 r / min, and the time was 6 h. Then it was dried at 110 °C to obtain the third powder after secondary ball milling. An 8 wt% aqueous PVA solution was added as a binder, and the addition amount was 12% of the mass of the third powder. After grinding evenly and passing through a 60-mesh sieve, it was pressed into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0063] Step 3, debinding and sintering

[0064] The thin circular blank was kept at 600 °C for 1 h to discharge the PVA solution, obtaining a ceramic green body; then the ceramic green body was sintered at 1090 °C for 4 h to prepare a sintered ceramic sheet, and the heating rate was not higher than 5 °C / min.

[0065] Step 4, electrode coating and poling

[0066] Both sides of the sintered ceramic sheet after sintering were polished to a thickness of 0.6 mm, platinum / gold electrodes were printed, and then it was kept at 900 °C for 30 min to complete the firing of the electrodes. Poling was carried out by applying a DC electric field of 10 kV / mm in 220 °C silicone oil for 40 min.

[0067] Example 4

[0068] The chemical general formula of the bismuth-layered composite piezoelectric ceramic material is (1 - x)Sm y Bi 4-y Ti3O 12 -xBi3Ti 1-Z (W 1 / 5 Ni 2 / 5Nb 2 / 5 ) Z Nb O9, where x = 0.2, y = 0.1, and z = 0.5.

[0069] Preparation of the bismuth-layered composite piezoelectric ceramic material:

[0070] Step 1, preparation of ceramic powder by solid-phase method

[0071] According to Sm 0.1 Bi 3.9 Ti3O 12For the stoichiometric ratio of (i.e., y = 0.1), weigh the raw materials of Sm2O3 samarium source, Bi2O3 bismuth source, and TiO2 titanium source, all with an analytical purity. Put the weighed raw materials into a nylon ball milling tank, use anhydrous ethanol as the dispersion medium, and the mass ratio of it to the total mass of the raw materials is 1:0.8. Use a planetary mill to mix for 4 h at a rotation speed of 300 rpm. Place the slurry in an oven at 110 °C for drying, and then pre-burn at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the first powder.

[0072] According to Bi3Ti 0.5 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.5 For the stoichiometric ratio of NbO9 (i.e., z = 0.5), weigh the raw materials of TiO2 titanium source, Nb2O5 niobium source, Bi2O3 bismuth source, WO3 tungsten source, and NiO nickel source, all with an analytical purity. Put the weighed raw materials into a nylon ball milling tank, use anhydrous ethanol as the dispersion medium, and the mass ratio of it to the total mass of the raw materials is 1:0.8. Use a planetary mill to mix for 4 h at a rotation speed of 150 rpm. Place the slurry in an oven at 110 °C for drying, and then pre-burn at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the second powder.

[0073] Step 2: Ball milling, granulation, and forming

[0074] Mix the above-mentioned first powder Sm 0.1 Bi 3.9 Ti3O 12 and the second powder Bi3Ti 0.5 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.5 NbO9 are proportioned according to 8:2 (i.e., x = 0.2). Then use a planetary ball mill with agate balls and anhydrous ethanol as the medium for secondary ball milling. The mass ratio of anhydrous ethanol to the total mass of the raw materials is 1:0.8, the condition is 200 r / min, and the time is 6 h. Then dry at 110 °C to obtain the third powder after secondary ball milling. Add an 8 wt% PVA aqueous solution as a binder, and the addition amount is 12% of the mass of the third powder. Grind evenly, pass through a 60-mesh sieve, and then press into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0075] Step 3: Debinding, sintering

[0076] The thin circular blank is kept at 600 °C for 1 h to discharge the PVA solution to obtain a ceramic green body; then the ceramic green body is sintered at 1120 °C for 4 h to obtain a sintered ceramic sheet, and the heating rate is not higher than 5 °C / min.

[0077] Step 4: Electrode coating and polarization

[0078] The two sides of the sintered ceramic sheet after sintering are polished to a thickness of 0.6 mm, platinum / gold electrodes are printed, and then fired at 950 °C for 10 min to complete the electrode firing. Polarization is carried out by applying a DC electric field of 12 kV / mm in silicone oil at 220 °C for 30 min.

[0079] Example 5

[0080] The chemical general formula of the bismuth-layered composite piezoelectric ceramic material is (1-x)Sm y Bi 4-y Ti3O 12 -xBi3Ti 1-Z (W 1 / 5 Ni 2 / 5Nb 2 / 5 ) Z NbO9, where x = 0.2, y = 0.2, and z = 0.1.

[0081] Preparation of the bismuth-layered composite piezoelectric ceramic material:

[0082] Step 1: Preparation of ceramic powder by solid-phase method

[0083] According to the stoichiometric ratio of Sm 0.2 Bi 3.8 Ti3O 12 (i.e., y = 0.2), weigh the raw materials of Sm2O3 samarium source, Bi2O3 bismuth source, and TiO2 titanium source, all with analytical purity. Put the weighed raw materials into a nylon ball mill tank, use anhydrous ethanol as the dispersion medium, with a mass ratio of 1:0.8 to the total mass of the raw materials, mix for 4 h using a planetary mill at a rotation speed of 300 rpm, dry the slurry in an oven at 110 °C, and then pre-burn at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the first powder.

[0084] According to the stoichiometric ratio of Bi3Ti 0.9 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.1 NbO9 (i.e., z = 0.1), weigh the raw materials of TiO2 titanium source, Nb2O5 niobium source, Bi2O3 bismuth source, WO3 tungsten source, and NiO nickel source, all with analytical purity. Put the weighed raw materials into a nylon ball mill tank, use anhydrous ethanol as the dispersion medium, with a mass ratio of 1:0.8 to the total mass of the raw materials, mix for 4 h using a planetary mill at a rotation speed of 150 rpm, dry the slurry in an oven at 110 °C, and then pre-burn at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the second powder.

[0085] Step 2: Ball milling, granulation, and forming

[0086] Mix the above-mentioned first powder Sm 0.2 Bi 3.8 Ti3O 12 and the second powder Bi3Ti 0.9 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.1 NbO9 in a ratio of 8:2 (i.e., x = 0.2). Then, use a planetary ball mill with agate balls and absolute ethanol as the medium for secondary ball milling. The mass ratio of absolute ethanol to the total mass of the raw materials is 1:0.8, the condition is 200 r / min, and the time is 6 h. Then, dry it at 110 °C to obtain the third powder after secondary ball milling. Add an 8 wt% PVA aqueous solution as a binder, and the addition amount is 12% of the mass of the third powder. Grind it evenly, pass through a 60-mesh sieve, and then press it into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0087] Step 3: Debinding, sintering

[0088] Keep the thin circular blank at 600 °C for 1 h to discharge the PVA solution and obtain a ceramic green body. Then, sinter the ceramic green body at 1120 °C for 4 h to prepare a sintered ceramic sheet, and the heating rate is not higher than 5 °C / min.

[0089] Step 4: Electroding, poling

[0090] Polish both sides of the sintered ceramic sheet after sintering to a thickness of 0.6 mm, print platinum / gold electrodes, and then keep it at 950 °C for 10 min to complete the firing of the electrodes. Apply a DC electric field of 12 kV / mm in 220 °C silicone oil and keep it for 30 min for poling.

[0091] Example 6

[0092] The chemical general formula of the bismuth-layered composite piezoelectric ceramic material is (1 - x)Sm y Bi 4-y Ti3O 12 - xBi3Ti 1-Z (W 1 / 5 Ni 2 / 5Nb 2 / 5 ) Z Nb O9, where x = 0.2, y = 0.2, and z = 0.3.

[0093] Preparation of the bismuth-layered composite piezoelectric ceramic material:

[0094] Step 1: Preparation of ceramic powder by solid-phase method

[0095] According to Sm 0.2 Bi3.8 Ti3O 12 For the stoichiometric ratio of (i.e., y = 0.2), weigh out the raw materials of Sm2O3 samarium source, Bi2O3 bismuth source, and TiO2 titanium source, all with analytical purity. Put the weighed raw materials into a nylon ball milling tank, use anhydrous ethanol as the dispersion medium, and the mass ratio of it to the total mass of the raw materials is 1:0.8. Use a planetary mill to mix for 4 h at a rotation speed of 300 rpm. Place the slurry in an oven at 110 °C for drying, and then pre-bake at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the first powder.

[0096] According to the stoichiometric ratio of Bi3Ti 0.7 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.3 NbO9 (i.e., z = 0.3), weigh out the raw materials of TiO2 titanium source, Nb2O5 niobium source, Bi2O3 bismuth source, WO3 tungsten source, and NiO nickel source, all with analytical purity. Put the weighed raw materials into a nylon ball milling tank, use anhydrous ethanol as the dispersion medium, and the mass ratio of it to the total mass of the raw materials is 1:0.8. Use a planetary mill to mix for 4 h at a rotation speed of 150 rpm. Place the slurry in an oven at 110 °C for drying, and then pre-bake at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the second powder.

[0097] Step 2: Ball milling, granulation, and forming

[0098] Mix the above-mentioned first powder Sm 0.2 Bi 3.8 Ti3O 12 and the second powder Bi3Ti 0.7 (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) 0.3 NbO9 according to a ratio of 8:2 (i.e., x = 0.2) for batching. Then use a planetary ball mill with agate balls and anhydrous ethanol as the medium for secondary ball milling. The mass ratio of anhydrous ethanol to the total mass of the raw materials is 1:0.8, the condition is 200 r / min, and the time is 6 h. Then dry at 110 °C to obtain the third powder after secondary ball milling. Add an 8 wt% aqueous PVA solution as a binder, and the addition amount is 12% of the mass of the third powder. Grind evenly, pass through a 60-mesh sieve, and then press into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0099] Step 3: Debinding, sintering

[0100] The thin circular blank is held at 600 °C for 1 h to discharge the PVA solution to obtain a ceramic green body; then the ceramic green body is sintered at 1120 °C for 4 h to obtain a sintered ceramic sheet, and the heating rate is not higher than 5 °C / min.

[0101] Step 4: Electroding and Polarization

[0102] The sintered ceramic sheet after sintering is polished on both sides to a thickness of 0.6 mm, platinum / gold electrodes are printed, and then fired at a temperature of 950 °C for 10 min to complete the electrode firing. Polarization is carried out by applying a DC electric field of 12 kV / mm in 220 °C silicone oil for 30 min.

[0103] Comparative Example 1

[0104] Preparation of piezoelectric ceramic material Bi4Ti3O 12 :

[0105] Step 1: Preparation of ceramic powder by solid-phase method

[0106] According to the stoichiometric ratio of Bi4Ti3O 12 , bismuth source Bi2O3 and titanium source TiO2 raw materials are weighed, and the purity of both is analytical pure. The weighed raw materials are put into a nylon ball mill tank, with absolute ethanol as the dispersion medium, and its mass ratio to the total mass of the raw materials is 1:0.8. The mixture is mixed for 8 h using a planetary mill at a rotation speed of 250 rpm. The slurry is dried in an oven at a temperature of 120 °C, and then pre-fired at a temperature of 800 °C with a heating rate of 3 °C / min and held for 6 h to obtain the first powder.

[0107] Step 2: Ball milling, granulation, and forming

[0108] The above-mentioned first powder is ball milled twice using a planetary ball mill with agate balls and absolute ethanol as the medium. The mass ratio of absolute ethanol to the total mass of the raw materials is 1:0.8, the condition is 200 r / min, and the time is 6 h. Then it is dried at 110 °C to obtain the second powder after secondary ball milling. An aqueous PVA solution with a concentration of 8 wt% is added as a binder, and the addition amount is 12% of the mass of the second powder. After grinding evenly and passing through a 60-mesh sieve, it is pressed into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0109] Step 3: Debinding and sintering

[0110] The thin circular blank is held at 600 °C for 1 h to discharge the PVA solution to obtain a ceramic green body; then the ceramic green body is sintered at 1090 °C for 4 h to obtain a sintered ceramic sheet, and the heating rate is not higher than 5 °C / min.

[0111] Step 4: Electroding and Polarization

[0112] The sintered ceramic sheet after sintering is polished on both sides to a thickness of 0.6 mm, platinum / gold electrodes are printed, and then fired at a temperature of 900 °C for 30 min to complete the electrode firing. Polarization is carried out by applying a DC electric field of 10 kV / mm in 220 °C silicone oil for 40 min.

[0113] Comparative Example 2

[0114] Piezoelectric ceramic material Sm y Bi 4-y Ti3O 12 Preparation, where y = 0.2:

[0115] Step 1: Preparation of ceramic powder by solid-phase method

[0116] According to the stoichiometric ratio of Sm 0.2 Bi 3.8 Ti3O 12 (i.e., y = 0.2), weigh the raw materials of Sm2O3 samarium source, Bi2O3 bismuth source, and TiO2 titanium source, all with an analytical purity. Put the weighed raw materials into a nylon ball-milling tank, use anhydrous ethanol as the dispersion medium, with a mass ratio of it to the total mass of the raw materials being 1:0.8, and use a planetary mill to mix for 8 h at a rotation speed of 250 rpm. Place the slurry in an oven at 120 °C for drying, and then pre-burn at 800 °C with a heating rate of 3 °C / min and hold for 6 h to obtain the first powder.

[0117] Step 2: Ball milling, granulation, and forming

[0118] Use the planetary ball mill to perform secondary ball milling on the above first powder with agate balls and anhydrous ethanol as the medium. The mass ratio of anhydrous ethanol to the total mass of the raw materials is 1:0.8, the condition is 200 r / min, and the time is 6 h. Then dry at 110 °C to obtain the second powder after secondary ball milling. Add an 8 wt% PVA aqueous solution as a binder, with an addition amount having a mass ratio of 12% to the mass of the second powder, grind evenly, pass through a 60-mesh sieve, and press into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0119] Step 3: Debinding and sintering

[0120] Pass the thin circular blank through 600 °C and hold for 1 h to discharge the PVA solution to obtain a ceramic green body; then sinter the ceramic green body at 1090 °C for 4 h to obtain a sintered ceramic sheet, with a heating rate not higher than 5 °C / min.

[0121] Step 4: Electroding and poling

[0122] Polish both sides of the sintered ceramic sheet after sintering to a thickness of 0.6 mm, print platinum / gold electrodes, and then hold at 900 °C for 30 min to complete the firing of the electrodes. Apply a DC electric field of 10 kV / mm in 220 °C silicone oil and hold for 40 min for poling.

[0123] Comparative Example 3

[0124] The chemical general formula of the bismuth-layered composite piezoelectric ceramic material is (1 - x)Sm y Bi4-y Ti3O 12 -xBi3Ti 1-Z (W 1 / 5 Ni 2 / 5Nb 2 / 5 ) Z NbO9, where x = 0.2, y = 0.2, z = 0.

[0125] Preparation of bismuth-layered composite piezoelectric ceramic materials:

[0126] Step 1. Preparation of ceramic powder by solid-phase method

[0127] According to the stoichiometric ratio of Sm 0.2 Bi 3.8 Ti3O 12 (i.e., y = 0.2), weigh the raw materials of Sm2O3 samarium source, Bi2O3 bismuth source, and TiO2 titanium source, all with analytical purity. Put the weighed raw materials into a nylon ball mill tank, use absolute ethanol as the dispersion medium, with a mass ratio of 1:0.8 to the total mass of the raw materials, mix them for 4 h using a planetary mill at a rotation speed of 300 rpm, place the slurry in an oven at 110 °C for drying, and then pre-burn at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the first powder.

[0128] According to the stoichiometric ratio of Bi3TiNbO9, weigh the raw materials of TiO2 titanium source, Nb2O5 niobium source, and Bi2O3 bismuth source, all with analytical purity. Put the weighed raw materials into a nylon ball mill tank, use absolute ethanol as the dispersion medium, with a mass ratio of 1:0.8 to the total mass of the raw materials, mix them for 4 h using a planetary mill at a rotation speed of 150 rpm, place the slurry in an oven at 110 °C for drying, and then pre-burn at 700 °C with a heating rate of 2 °C / min and hold for 3 h to obtain the second powder.

[0129] Step 2. Ball milling, granulation, and forming

[0130] Mix the above-mentioned first powder Sm 0.2 Bi 3.8 Ti3O 12 and the second powder Bi3TiNbO9 according to a ratio of 8:2 (i.e., x = 0.2), then use a planetary ball mill with agate balls and absolute ethanol as the medium for secondary ball milling. The mass ratio of absolute ethanol to the total mass of the raw materials is 1:0.8, the conditions are 200 r / min and the time is 6 h, and then dry at 110 °C to obtain the third powder after secondary ball milling. Add an 8 wt% aqueous PVA solution as a binder, with an addition amount of 12% of the mass of the third powder, grind evenly, pass through a 60-mesh sieve, and press into a thin circular blank with a diameter of 15 mm and a thickness of 2 mm.

[0131] Step 3. Debinding and sintering

[0132] The thin circular blank is kept at 600 °C for 1 h to discharge the PVA solution, obtaining a ceramic green body; then the ceramic green body is sintered at 1120 °C for 4 h to obtain a sintered ceramic sheet, and the heating rate is not higher than 5 °C / min.

[0133] Step 4: Electrodes and polarization

[0134] Both sides of the sintered ceramic sheet after sintering are polished to a thickness of 0.6 mm, platinum / gold electrodes are printed, and then it is kept at 950 °C for 10 min to complete the firing of the electrodes. Polarization is carried out by applying a DC electric field of 12 kV / mm in 220 °C silicone oil for 30 min.

[0135] Test examples

[0136] Piezoelectric performance tests were carried out on the piezoelectric ceramic materials prepared in Examples 1-6 and Comparative Examples 1-3. The test results are shown in Table 1. Among them, the curve of the dielectric constant of the piezoelectric ceramic material provided in Example 1 changing with temperature is as Figure 1 shown; the piezoelectric ceramic materials provided in Examples 1-6 and Comparative Examples 1-3 were annealed in the temperature range of 150-700 °C, kept at each temperature point for 2 h, and the piezoelectric constants were tested. The test results are as Figure 2 shown.

[0137] Table 1: Main performance parameters of piezoelectric ceramics

[0138]

[0139]

[0140] Combined with Table 1, Figure 2 , in the piezoelectric ceramic material of the example, samarium (Sm 3+ ) is doped at the A site of the BIT-based ceramic, and tungsten, niobium, and nickel ion groups (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) are doped at the B site of the Bi3TiNbO9-based ceramic 4+ for modification. Moreover, the two modified BIT-based ceramics and the Bi3TiNbO9-based ceramic are compounded, and the piezoelectric ceramic performance of the BIT-based is improved by three means. Co-doping at the A and B sites can better exert the advantages of multi-component composite doping modification. The prepared BIT-based ceramic has the advantages of a large piezoelectric constant, a high Curie temperature, and a high high-temperature resistivity. The piezoelectric constant d 33 of the BIT-based ceramic is increased from 8 pC / N to 26.6 pC / N, and the high-temperature resistivity is increased from 5×10 5 Ω·cm@500 °C to 1.3×10 7Ω·cm at 500 °C, indicating that the piezoelectric ceramic material provided by the embodiment has good stability before 500 °C and has the potential to be assembled for use in high-temperature sensors at 500 °C.

[0141] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0142] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A bismuth-layered composite piezoelectric ceramic material, characterized in that, In the Bi4Ti3O 12 -based ceramics, samarium ions are doped at the A site, and tungsten, nickel, and niobium ion groups are doped at the B site in the Bi3TiNbO9-based ceramics. Moreover, the Bi4Ti3O 12 -based ceramics are combined with the Bi3TiNbO9-based ceramics; Its chemical general formula is (1-x)Sm y Bi 4-y Ti3O 12 -xBi3Ti 1-Z (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) Z NbO9, where 0 < x ≤ 0.3, 0 < y ≤ 0.2, 0 < z ≤ 0.

5.

2. A preparation method of the bismuth layer-structured composite piezoelectric ceramic material as described in claim 1, characterized in that, It includes the following steps: Step 1. Weigh the raw materials for forming Sm y Bi 4-y Ti3O 12 ceramic powder according to stoichiometry, mix them into a slurry, dry the slurry, and pre-sinter to obtain the first powder; Weigh the raw materials for forming Bi3Ti 1-Z (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) Z NbO9 ceramic powder according to stoichiometry, mix them into a slurry, dry the slurry, and pre-sinter to obtain the second powder; Step 2: After secondary ball milling the first powder and the second powder according to the ratio of (1 - x):x, drying them to obtain the third powder, then adding a binder to the third powder for grinding and granulation, sieving, and pressing into a shape to obtain a thin circular blank; Step 3: Debinding and sintering the thin circular blank to obtain a sintered ceramic sheet; Step 4: Polishing both sides of the sintered ceramic sheet and printing electrodes, then sintering the electrodes, placing it in silicone oil and applying a voltage for polarization to obtain a bismuth-layered composite piezoelectric ceramic material.

3. The preparation method according to claim 2, characterized in that, In Step 1, Sm is formed y Bi 4-y Ti3O 12 The raw materials for the ceramic powder include Sm2O3, Bi2O3 and TiO2 titanium source; forming Bi3Ti 1-Z (W 1 / 5 Ni 2 / 5 Nb 2 / 5 ) Z The raw materials for the (W, Ni, Nb) NbO9 ceramic powder include TiO2, Nb2O5, Bi2O3, WO3 and NiO.

4. The preparation method according to claim 2, characterized in that, In Step 1, during mixing, using anhydrous ethanol as the dispersion medium, mixing with a planetary mill for 4 h to 8 h at a rotation speed of 150 rpm to 300 rpm; during drying, drying the slurry at a temperature of 110°C to 130°C; during pre-sintering, pre-sintering at a temperature of 700°C to 850°C with a heating rate of 2°C / min to 3°C / min and holding for 3 h to 6 h to obtain the first powder or the second powder.

5. The preparation method according to claim 2, characterized in that, In Step 2, the conditions for secondary ball milling are 200 r / min and the time is 6 h, and the drying temperature is 110°C to 130°C.

6. The preparation method according to claim 2, wherein In Step 2, the binder is an aqueous PVA solution with a concentration of 8 wt%, and the aqueous PVA solution accounts for 12% of the mass of the third powder.

7. The preparation method according to claim 2, characterized in that, In Step 3, debinding is to discharge the binder by holding at 600°C to 850°C for 1 h; sintering is to sinter the thin circular blank at 1060°C to 1120°C for 2 h to 4 h with a heating rate not higher than 5°C / min.

8. The preparation method according to claim 2, characterized in that, In Step 4, printing platinum / gold electrodes on the sintered ceramic sheet polished on both sides, and then sintering the electrodes at a temperature of 900°C to 1000°C and holding for 10 min to 30 min.

9. The preparation method according to claim 2, characterized in that, In Step 4, applying a DC electric field of 10 kV / mm to 14 kV / mm in silicone oil at 200°C to 220°C and holding for 20 min to 40 min.

10. A piezoelectric device, characterized in that, It includes the bismuth-layered composite piezoelectric ceramic material described in Claim 1 or the bismuth-layered composite piezoelectric ceramic material prepared by the preparation method described in any one of Claims 2 - 8.

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