Low-loss bismuth scandate-lead titanate-based high-temperature piezoelectric ceramic material and preparation method thereof

Abstract

The invention discloses a low-loss bismuth scandate-lead titanate based piezoelectric ceramic material and a preparation method thereof. The general chemical formula of the piezoelectric ceramic material is y [(1-x) BiScO3-xBiFeO3]-(1-y) PbTiO3-0. 02GeO, x is equal to 0-0.30, y is equal to 0.36-0.38, and the piezoelectric ceramic material can be prepared by taking a metal oxide and / or a metal carbonate in a stoichiometric ratio as a raw material and adopting a traditional solid-phase reaction method. According to the invention, the dielectric loss tan delta and mechanical loss of the material are greatly reduced, and meanwhile, the material also has high Curie temperature and excellent piezoelectric property.

Description

Technical Field

[0001] The present invention belongs to the field of piezoelectric ceramic materials, and relates to piezoelectric ceramic materials used in relatively high temperature environments, and specifically relates to a low-loss, high-Curie-temperature bismuth scandate-lead titanate piezoelectric ceramic material and a preparation method thereof. Background Art

[0002] Piezoelectric materials have the unique ability to convert mechanical energy into electrical energy, so they are widely used in sensors, actuators, transducers, and energy harvesters. High-temperature piezoelectric devices can operate at temperatures above 200-300°C and are particularly popular in aerospace, automotive industry, and deep oil exploration. Piezoelectric ceramic materials are the core components of the entire system. Therefore, the performance parameters of piezoelectric ceramic materials, especially the high-temperature piezoelectric properties and high-temperature dielectric loss of the materials, directly determine the performance of the system. A higher Curie temperature generally means a high operating temperature; while a low dielectric loss means the performance stability of the device or system at long-term operation at high temperatures. When high-temperature ceramics are used as sensors, low dielectric loss means lower noise signals at high temperatures, so the sensor has higher sensitivity.

[0003] The currently dominant commercial piezoelectric ceramic, Pb(Zr,Ti)O3 (PZT), has excellent piezoelectric properties at the micromorphic phase boundary (MPB), can be easily tuned by chemical modification, and is inexpensive to manufacture, but its operating temperature is generally limited to 200°C due to severe thermal depolarization above this threshold. In contrast, BiScO3-PbTiO3 (BS-PT) solid solutions have emerged as promising candidates for high-temperature piezoelectric applications. These materials have high piezoelectric coefficients d of 450 pC / N. 33 and Curie temperature of 450°C, large-scale research is devoted to understanding its piezoelectric properties, tailoring its electrical characteristics through chemical modification and process control, and exploring its potential applications in high-temperature actuators, energy harvesters, sensors, and ultrasonic transducers.

[0004] Perovskite ferroelectric bismuth scandate-lead titanate (BiScO3-PbTiO3) has attracted attention for its electrical properties comparable to those of PZT-based ceramics and its high Curie temperature of 450°C. However, due to its large dielectric loss, continuous operation at high temperature and high frequency will cause serious energy loss. Although some researchers have also introduced manganese dioxide (MnO2), lead manganate niobate (Pb(Nb,Mn)O3) and lead manganate antimonate (Pb(Mn,Sb)O3) to reduce dielectric loss, this method has limited suppression of dielectric loss and often leads to severe degradation of piezoelectric performance. In high-temperature piezoelectric applications, it is crucial to consider both the thermal stability and loss of piezoelectric performance. New strategies are urgently needed to optimize the mechanical and dielectric losses of BS-PT ceramics for use in high-temperature and high-power piezoelectric devices.

[0005] Therefore, in order to solve the above problems, it is urgent to develop a piezoelectric ceramic with low loss, high Curie temperature, excellent piezoelectric performance and temperature stability to meet market demand. Summary of the invention

[0006] The object of the present invention is to provide a dielectric having low dielectric loss tanδ and high Curie temperature T c To achieve this purpose, the present invention introduces bismuth ferrite BiFeO3 with a perovskite structure and glass phase GeO2 as doping to form a solid solution with bismuth scandate-lead titanate, thereby obtaining a new bismuth scandate-lead titanate system high-temperature piezoelectric ceramic material, which has low dielectric loss and high piezoelectric performance, while ensuring a Curie temperature of nearly 500°C and temperature stability. This material has practical application value in the field of high-temperature electronic materials.

[0007] To achieve the above object, the technical solution adopted by the present invention comprises the following steps:

[0008] A bismuth scandate-lead titanate-based piezoelectric ceramic material, the chemical formula of which is y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0-0.3, y=0.36-0.38. The crystal structure of the piezoelectric ceramic material is a perovskite structure, the dielectric loss tanδ is low (0.4%-0.6%), and it has a high Curie temperature Tc (above 450°C) and excellent piezoelectric properties (d 33 ~200pC / N,k p ~0.33,Q m~600). The present invention also provides a method for preparing the above-mentioned bismuth scandate-lead titanate-based piezoelectric ceramic material, which can be prepared by a conventional solid phase reaction method using oxides and / or carbonates of metals Sc, Bi, Fe, Pb, Ti and Ge in a stoichiometric ratio as raw materials. The raw materials are selected from the following compounds: Sc2O3, Bi2O3, Fe2O3, PbO, TiO2 and GeO2. The raw material purity is preferably analytically pure 99%. The preparation method of the above-mentioned bismuth zirconate scandate-lead titanate-based piezoelectric ceramic material specifically includes the following steps:

[0009] (1) weighing raw materials according to the stoichiometric ratio of the chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein the raw materials are oxides and / or carbonates of Sc, Bi, Fe, Pb, Ti and Ge, and mixing them uniformly by wet ball milling;

[0010] (2) drying the ball-milled mixture, pre-burning it at 750-850°C for a period of time, and then performing a second ball milling;

[0011] (3) drying the powder after the secondary ball milling, adding a binder to press and shape it, and performing a plastic removal treatment to obtain a ceramic blank;

[0012] (4) sintering the ceramic green body at 1000-1100° C. to obtain a ceramic sheet;

[0013] (5) Electrode-polarizing the sintered ceramic sheet to obtain the bismuth scandate-lead titanate-based piezoelectric ceramic material.

[0014] In the above step (1), preferably, water and / or ethanol are added to the raw material for wet ball milling. In some embodiments of the present invention, anhydrous ethanol is added as a grinding aid, the ball mill speed is preferably 200-300 rpm, and the ball milling time is preferably 12-14 hours.

[0015] In the above step (2), the drying temperature is preferably 60-90°C, the pre-calcination temperature is preferably 750-850°C, and the pre-calcination time is preferably 2-6 hours. Water and / or ethanol are preferably added to the secondary ball milling for wet ball milling. In some embodiments of the present invention, anhydrous ethanol is added as a grinding aid, the ball mill speed is preferably 200-300 rpm, and the ball milling time is preferably 6-10 hours.

[0016] In the above step (3), the amount of the binder is preferably 2-5% of the total weight of the mixed powder. The binder is preferably polyvinyl alcohol (PVA). In some embodiments of the present invention, an 8% by weight PVA aqueous solution is used as the binder, and the extrusion temperature is 600°C.

[0017] In the above step (4), the heating rate of the sintering furnace is preferably 250-300° C. / hour, and the sintering time is preferably 2-4 hours.

[0018] In the above step (5), the sintered ceramic sheet is polished on both sides and electrodes are made, and then polarized at a higher temperature (for example, 120-140°C). The electrode material is preferably silver or gold. Preferably, silver is burned on the polished ceramic sheet on both sides as an electrode, and the silver burning treatment conditions are 600°C and the time is 10 to 30 minutes; then polarized in heated silicone oil. More preferably, the conditions for the polarization treatment are a silicone oil temperature of 120°C, a polarizing DC electric field of 4 to 5 kV / mm, and a polarization time of 15 to 30 minutes. Through the above technical scheme, the beneficial effects of the technical scheme of the present invention are:

[0019] (1) The bismuth scandate-lead titanate high-temperature piezoelectric ceramic material provided by the present invention has extremely low dielectric loss (tanδ=0.4%-0.6%), excellent electrical properties (d33-200pC / N, kp-0.33, Qm-600) and high Curie temperature (above 450°C). The material provided by the present invention can meet the requirements of resonant drive, high voltage actuation, and service use of sensitive components such as high-frequency transducers and sensors in a relatively high temperature environment. It has practical application value in high-temperature electronic devices and has obvious advantages in high-frequency, high-voltage drive, or high-frequency acoustic transducers and sensors.

[0020] (2) The high-temperature piezoelectric ceramic material provided by the present invention can be prepared by a traditional solid-phase reaction method. The preparation process is simple and stable, and the operation is convenient. At the same time, its lower synthesis sintering temperature is conducive to the preparation of multilayer co-fired ceramics and cost savings. It is suitable for promotion of large-scale industrial production and has practical application value and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the implementation of the present application, the following is a brief introduction to the relevant drawings. It is understood that the drawings described below are only used to illustrate some implementations of the present application, and those skilled in the art can also obtain many other technical features not mentioned herein based on these drawings.

[0022] Figure 1 This is a SEM scanning electron microscope micrograph of the bismuth zirconate manganate-bismuth scandate-lead titanate piezoelectric ceramic material prepared in Examples 1-7 of the present invention.

[0023] Figure 2 XRD spectra of the ceramic materials prepared in Examples 1-7;

[0024] Figure 3The dielectric temperature spectrum of the ceramic materials prepared in Examples 1, 3, and 7, the test frequency is 10 KHz;

[0025] Figure 4 The graphs showing the piezoelectric coefficients of the ceramic materials prepared in Examples 1, 3, and 7 changing with temperature.

[0026] Figure 5 The graphs of the planar electromechanical coupling coefficient of the ceramic materials prepared in Examples 1, 3, and 7 as a function of temperature are shown. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Implementation Method 1

[0029] A modified piezoelectric ceramic having a chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0 and y=0.36, was prepared.

[0030] Analytically pure raw materials Sc2O3, Bi2O3, Fe2O3, PbO, TiO2 and GeO2 are mixed according to the above-mentioned metering ratio, put into a ball mill and mixed for 12 hours, and the planetary ball mill is maintained at a speed of 250 rpm; pre-fired at 700°C for 3 hours; the pre-fired powder is ball-milled for a second time for 8 hours; after the material is taken out and dried, PVA solution is added and ground and pressed into a thin round billet with a diameter of 15 mm, and plastic removal treatment is carried out at 600°C; then the ceramic round billet is sintered at 1100°C for 3 hours; the sintered ceramic sample is polished on both sides, silver-sintered with Ag electrodes, and a DC electric field of 5kV / mm is applied in 120°C silicone oil for 30 minutes to obtain 0.36BiScO3-0.64PbTiO3-0.02GeO2 ceramics.

[0031] Implementation Method 2

[0032] A modified piezoelectric ceramic having a chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0.1 and y=0.36, was prepared.

[0033] The analytically pure raw materials Sc2O3, Bi2O3, Fe2O3, PbO, TiO2 and GeO2 are mixed according to the above-mentioned metering ratio, put into a ball mill, mixed and ball-milled for 12 hours, and the planetary ball mill is maintained at a speed of 250 rpm; pre-fired at 700°C for 3 hours; the pre-fired powder is ball-milled for a second time for 8 hours; after the material is taken out and dried, PVA solution is added and ground and pressed into a thin round billet with a diameter of 15 mm, and plastic removal treatment is carried out at 600°C; then the ceramic round billet is sintered at 1100°C for 3 hours; the sintered ceramic sample is polished on both sides, silver-sintered with Ag electrodes, and a DC electric field of 5kV / mm is applied in 120°C silicone oil for 30 minutes to obtain 0.36[0.90(BiScO3-0.10BiFeO3)]-0.64PbTiO3-0.02GeO2 ceramics.

[0034] Implementation Method 3

[0035] A modified piezoelectric ceramic having a chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0.10 and y=0.38, was prepared.

[0036] The analytically pure raw materials Sc2O3, Bi2O3, Fe2O3, PbO, TiO2 and GeO2 are mixed according to the above-mentioned metering ratio, put into a ball mill, mixed and ball-milled for 12 hours, and the planetary ball mill is maintained at a speed of 250 rpm; pre-fired at 700°C for 3 hours; the pre-fired powder is ball-milled for a second time for 8 hours; after the material is taken out and dried, PVA solution is added and ground and pressed into a thin round billet with a diameter of 15 mm, and plastic removal treatment is carried out at 600°C; then the ceramic round billet is sintered at 1100°C for 3 hours; the sintered ceramic sample is polished on both sides, silver-sintered with Ag electrodes, and a DC electric field of 5kV / mm is applied in 120°C silicone oil for 30 minutes to obtain 0.38[0.90(BiScO3-0.10BiFeO3)]-0.62PbTiO3-0.02GeO2 ceramics.

[0037] Implementation Method 4

[0038] A modified piezoelectric ceramic having a chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0.20 and y=0.36, was prepared.

[0039] The analytically pure raw materials Sc2O3, Bi2O3, Fe2O3, PbO, TiO2 and GeO2 are mixed according to the above-mentioned metering ratio, put into a ball mill, mixed and ball-milled for 12 hours, and the planetary ball mill is maintained at a speed of 250 rpm; pre-fired at 700°C for 3 hours; the pre-fired powder is ball-milled for a second time for 8 hours; after the material is taken out and dried, PVA solution is added and ground and pressed into a thin round billet with a diameter of 15 mm, and plastic removal treatment is carried out at 600°C; then the ceramic round billet is sintered at 1100°C for 3 hours; the sintered ceramic sample is polished on both sides, silver-sintered with Ag electrodes, and a DC electric field of 5kV / mm is applied in 120°C silicone oil for 30 minutes to obtain 0.36[0.80(BiScO3-0.20BiFeO3)]-0.64PbTiO3-0.02GeO2 ceramics.

[0040] Implementation Method 5

[0041] A modified piezoelectric ceramic having a chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0.20 and y=0.38, was prepared.

[0042] The analytically pure raw materials Sc2O3, Bi2O3, Fe2O3, PbO, TiO2 and GeO2 are mixed according to the above-mentioned metering ratio, put into a ball mill, mixed and ball-milled for 12 hours, and the planetary ball mill is maintained at a speed of 250 rpm; pre-fired at 700°C for 3 hours; the pre-fired powder is ball-milled for a second time for 8 hours; after the material is taken out and dried, PVA solution is added and ground and pressed into a thin round billet with a diameter of 15 mm, and plastic removal treatment is carried out at 600°C; then the ceramic round billet is sintered at 1100°C for 3 hours; the sintered ceramic sample is polished on both sides, silver-sintered with Ag electrodes, and a DC electric field of 5kV / mm is applied in 120°C silicone oil for 30 minutes to obtain 0.38[0.80(BiScO3-0.20BiFeO3)]-0.62PbTiO3-0.02GeO2 ceramics.

[0043] Implementation Method 6

[0044] A modified piezoelectric ceramic having a chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0.30 and y=0.36, was prepared.

[0045] The analytically pure raw materials Sc2O3, Bi2O3, Fe2O3, PbO and TiO2 are prepared according to the above-mentioned metering ratio, put into a ball mill and mixed for 12 hours, with the planetary ball mill maintained at a speed of 250 rpm; pre-fired at 700°C for 3 hours; the pre-fired powder is ball-milled for a second time for 8 hours; after drying the material, PVA solution is added and ground and pressed into a thin round billet with a diameter of 15 mm, which is subjected to a plastic removal treatment at 600°C; the ceramic round billet is then sintered at 1100°C for 3 hours; the sintered ceramic sample is polished on both sides, silver-sintered with an Ag electrode, and a DC electric field of 5 kV / mm is applied in 120°C silicone oil for 30 minutes to obtain 0.36[0.70(BiScO3-0.30BiFeO3)]-0.64PbTiO3-0.02GeO2 ceramics.

[0046] Implementation Method 7

[0047] A modified piezoelectric ceramic having a chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0.30 and y=0.38, was prepared.

[0048] The analytically pure raw materials Sc2O3, Bi2O3, Fe2O3, PbO and TiO2 are prepared according to the above-mentioned metering ratio, put into a ball mill and mixed for 12 hours, with the planetary ball mill maintained at a speed of 250 rpm; pre-fired at 700°C for 3 hours; the pre-fired powder is ball-milled for a second time for 8 hours; after drying the material, PVA solution is added and ground and pressed into a thin round billet with a diameter of 15 mm, which is subjected to a plastic removal treatment at 600°C; the ceramic round billet is then sintered at 1100°C for 3 hours; the sintered ceramic sample is polished on both sides, silver-sintered with an Ag electrode, and a DC electric field of 5 kV / mm is applied in 120°C silicone oil for 30 minutes to obtain 0.38[0.70(BiScO3-0.30BiFeO3)]-0.62PbTiO3-0.02GeO2 ceramics.

[0049] Figure 1 (a)-(g) are SEM images of the thermally etched ceramic materials of Examples 1 to 7. These images show that the ceramic samples are relatively dense, with distinct grain boundaries and minimal porosity, and well-developed grains. These properties indicate that the ceramics have strong mechanical strength, which is critical for high-power piezoelectric applications.

[0050] from Figure 2 In the XRD diagram, we can find that y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, where x=0-0.30 and y=0.36-0.38, the ceramic material is well crystallized, showing a single perovskite phase, and no secondary phase is detected.

[0051] Figure 3 The temperature variation of dielectric properties of ceramics of Examples 1, 3 and 7 is shown. The Curie temperature Tc (the position of the maximum dielectric constant) of the ceramic of Example 7 is close to 500° C. In addition, the introduction of BiFeO3 and GeO2 improves the dielectric thermal stability of the ceramic.

[0052] Figure 4 and Figure 5 The piezoelectric coefficient and planar electromechanical coupling coefficient of the ceramic materials of Examples 1, 3, and 7 are respectively plotted against temperature. It can be seen from the figure that the ceramic of Example 7 has the best piezoelectric temperature stability.

[0053] In summary, 0.38[0.70(BiScO3-0.30BiFeO3)]-0.62PbTiO3-0.02GeO2 ceramics have the best comprehensive performance, with a high Curie temperature of 493°C, a low dielectric loss of 0.4%, a high mechanical quality factor of 600, a high piezoelectric coefficient of 220, and a high electromechanical coupling coefficient of 0.33, which can meet the needs of low-loss high-temperature piezoelectric ceramics.

[0054] Finally, it should be noted that the above description of the comparative embodiments of the present invention describes the technical principles, but it cannot be understood as a limitation of rights. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application will fall within the scope of protection of the claims of the present invention.

Claims

1. A low-loss bismuth scandate-lead titanate-based high-temperature piezoelectric ceramic material, characterized in that: The chemical composition of the ceramic material is y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein x=0-0.30, y=0.36-0.38; the Curie temperature T c At 440-490℃, the piezoelectric coefficient d 33 It is 180-320pC / N.

2. The piezoelectric ceramic material according to claim 1, characterized in that: The crystal structure of the piezoelectric ceramic material is a perovskite structure.

3. A method for preparing the piezoelectric ceramic material according to claim 1 or 2, using oxides and / or carbonates of Sc, Bi, Fe, Pb, Ti and Ge in a stoichiometric ratio as raw materials and adopting a solid phase reaction method.

4. The method according to claim 3, characterized in that The Sc, Bi, Fe, Pb, Ti and Ge are derived from the following compounds: Sc2O3, Bi2O3, Fe2O3, PbO, TiO2 and GeO2.

5. The method according to claim 3, characterized in that The method comprises the following steps: 1) weighing raw materials according to the stoichiometric ratio of the chemical composition of y[(1-x)BiScO3-xBiFeO3]-(1-y)PbTiO3-0.02GeO, wherein the raw materials are oxides and / or carbonates of Sc, Bi, Zr, Pb, Ti and Ge, and mixing them uniformly by wet ball milling; 2) Dry the ball-milled mixture, pre-sinter it at 750-850°C for a period of time, and then perform secondary ball milling; 3) drying the powder after the secondary ball milling, adding a binder to press and shape it, and performing a plastic removal treatment to obtain a ceramic blank; 4) sintering the ceramic green body at 1000-1100° C. to obtain a ceramic sheet; 5) The sintered ceramic sheet is electrically polarized to obtain a bismuth scandate-lead titanate-based piezoelectric ceramic material.

6. The method according to claim 5, characterized in that In step 1), water and / or ethanol are added to the raw materials for wet ball milling. The ball mill speed is 200 to 300 rpm, and the ball milling time is preferably 12 to 14 hours.

7. The method according to claim 5, characterized in that In the step 2), the drying temperature is 60-90°C, the pre-firing temperature is 750-850°C, and the pre-firing time is 2-6 hours; Water and / or ethanol are added during the secondary ball milling for wet ball milling; the ball mill speed is 200 to 300 rpm, and the ball milling time is 6 to 10 hours.

8. The method according to claim 5, characterized in that In the step 3), the binder is polyvinyl alcohol, and its usage is 2-5% of the total mass of the mixed powder.

9. The method according to claim 5, characterized in that In the step 4), the temperature is raised to 1000-1100° C. at a heating rate of 250-300° C. / hour and sintered for 2-4 hours.

10. The method according to claim 5, characterized in that In the step 5), both sides of the sintered ceramic sheet are polished and electrodes are formed, and then the electrodes are polarized in silicone oil at 100-120°C.

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