CN111908917A - Sodium bismuth zirconate strontium doped potassium sodium niobate based piezoelectric ceramic material and preparation method thereof - Google Patents

Abstract

The invention discloses a bismuth sodium strontium zirconate doped potassium sodium niobate based piezoelectric ceramic material and a preparation method thereof. KNN)-based ceramic powder materials; then bismuth sodium strontium zirconate doped KNN-based ceramics were prepared by electronic ceramic preparation processes such as granulation and tableting, debinding, sintering, and silver testing. The piezoelectric and dielectric properties of KNN are greatly improved by the doping of the component Sr(BiNa)ZrO ₃ , and the KNN has good temperature stability, which is expected to prepare piezoelectric devices.

Description

A kind of bismuth sodium strontium zirconate doped potassium sodium niobate based piezoelectric ceramic material and preparation method thereof

technical field

The invention relates to a bismuth, sodium and strontium zirconate doped potassium and sodium niobate-based piezoelectric ceramic material and a preparation method thereof. Specifically, a certain content of zirconic acid is simultaneously mixed in the preparation process of the potassium and sodium niobate-based material. Bismuth sodium strontium, through specific polarization methods to obtain high-voltage electrical properties. The invention belongs to the field of material science and engineering.

Background technique

Piezoelectric ceramics are widely used in various electronic components such as sensors, drivers, ultrasonic transducers, resonators, filters, etc. due to their excellent performance, simple preparation process and low cost. At present, lead-containing piezoelectric ceramics widely used in the market are not conducive to the sustainable development of human beings and the ecological environment. High-performance lead-free piezoelectric ceramics, especially high-performance lead-free piezoelectric ceramics with perovskite structure, have become the focus and focus of international research in recent years because of their excellent piezoelectric properties.

Potassium sodium niobate (K,Na)NbO ₃ is a piezoelectric material with perovskite structure. The piezoelectric constant d ₃₃ of pure potassium sodium niobate ceramics prepared by ordinary sintering process is only about 80 pC/N. Some scholars use spark plasma sintering or hot pressing sintering to prepare potassium sodium niobate-based piezoelectric ceramics, the d ₃₃ can reach ~250pC/N, which can improve the mechanical properties of the material itself, and has a high density, but the material stability Poor, the size is limited, and the process equipment is relatively expensive, not suitable for industrial production. Chemical doping in potassium sodium niobate-based ceramics can effectively improve the sintering properties of the ceramics, obtain high-density ceramic bodies, and significantly improve their piezoelectric properties (200~400pC/N). The doping-modified potassium and sodium niobate-based ceramics can have relatively high piezoelectric properties even with traditional preparation techniques. There is no report on potassium sodium niobate-based ceramics doped with sodium strontium bismuth zirconate.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a kind of bismuth sodium strontium zirconate doped potassium sodium niobate based piezoelectric ceramic material for the deficiencies of the prior art. It is characterized by the doping modification of potassium and sodium niobate-based ceramics by chemical doping to construct a multiphase coexisting ceramic system at room temperature. The method greatly improves the piezoelectric properties and dielectric properties of potassium sodium niobate ceramics.

A kind of bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic material, characterized in that the preparation process is as follows:

(1) Preparation of potassium sodium niobate-based ceramic powder by solid-phase method

The raw materials are respectively according to the general formula (K _0.48 Na _0.52 )(Nb _0.97 Sb _0.03 )O ₃ -0.05Sr _x (Bi _0.5 Na _0.5 ) _{(1- x )} ZrO ₃ -0.0015Fe ₂ O ₃ (wherein x represents that Sr replaces Bi The molar fraction of _0.5 Na _0.5 , the range of values is: 0.0 ≤ x ≤ 0.3; doping elements are added with oxides or carbonates), weighed and batched, placed in a polyurethane ball mill, and anhydrous ethanol was used as the The dispersion medium is milled with a planetary ball mill for 8 to 24 hours at a rotational speed of 150 to 250 rpm, baked under a drying lamp for 1 to 2 hours, then heated to 850°C in a programmed temperature box furnace, and kept for 6 hours to obtain niobium. Potassium-sodium-based ceramic powder.

(2) Granulation and tableting

A polyvinyl alcohol solution with a concentration of 5~10wt% is added to the above-mentioned dried powder, and it is fully mixed, and then granulated, and then pressed to a diameter of 10~12 mm and a thickness of 0.8~1.2mm under the pressure of 10~15 MPa. bismuth sodium strontium zirconate doped potassium sodium niobate based ceramic discs.

(3) Debinding and sintering

The above-mentioned potassium and sodium niobate-based ceramic discs are degummed at a temperature of 800-900 DEG C, and then sintered at a temperature of 1050-1150 DEG C for 3-5 hours to prepare bismuth sodium strontium zirconate-doped potassium sodium niobate-based ceramic discs.

(4) Polarized by silver

The bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic disc obtained after sintering is brushed with silver paste with a concentration of 5-15wt%, and then sintered at a temperature of 600-700°C for 10-15 minutes to prepare a sample. The sample was polarized in a silicone oil bath at 20-80 °C, the polarization field strength was 3-5 kV/mm, and the pressure holding time was 5-30 min, to prepare bismuth sodium strontium zirconate doped potassium sodium niobate base voltage. Electric ceramics.

The bismuth, sodium and strontium zirconate doped potassium and sodium niobate-based piezoelectric ceramics are prepared from bismuth, sodium and strontium zirconate doped potassium and sodium niobate, and their piezoelectric properties are: Piezoelectric constant d ₃₃ : 370~475 pC/ N, electromechanical coupling coefficient k _p : 0.47~0.56, _remanent polarization Pr : 19~24 μC/cm ² , coercive field E _c : 7.5~9.0 kV/cm.

The application of the bismuth sodium strontium zirconate doped potassium sodium niobate based ceramic material as a lead-free piezoelectric ceramic material.

Structural characterization and performance testing:

1 The phase structure of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic disc was analyzed by X-ray diffractometer (XRD, DX-2700); see Figure 1 for details. The results show that the bismuth sodium strontium zirconate doped potassium sodium niobate based piezoelectric ceramics is a single perovskite structure, showing a multiphase coexisting crystal structure at room temperature;

2 The surface morphology of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic disc was observed by electron microscope (SEM, S-3400N); see Figure 2 for details. The results show that the grain size of potassium sodium niobate based piezoelectric ceramics doped with bismuth sodium strontium zirconate is not uniform.

3 The domain structure of bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic discs was observed by piezoelectric force microscope (PFM, Asylum Research), as shown in Fig. 3 for details. The results show that the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic has random nano-domains with a domain size close to 1 μm, and the sub-micron domains improve its piezoelectric performance;

4 The d ₃₃ and K _p of bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic wafers were tested by d ₃₃ piezoelectric tester (ZJ-3A) and impedance analyzer (HP 4294A); see Fig. 4 for details. Show. The results show that: bismuth sodium strontium zirconate doped potassium sodium niobate-based piezoelectric ceramics have relatively excellent piezoelectric constant and excellent electromechanical coupling coefficient;

5 The high temperature and low temperature dielectric temperature curves of bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic wafers were tested by LCR analyzer (HP 4980, TH2816A); see Figure 5 and Figure 6 for details. The results show that the bismuth sodium strontium zirconate doped potassium sodium niobate-based piezoelectric ceramic has a higher Curie temperature, and the ceramic builds a trigonal-orthogonal-tetragonal phase boundary at room temperature to improve its piezoelectric performance;

6 Using a ferroelectric analyzer (aixACCT TF Analyzer 1000), the hysteresis loop and uniaxial strain curve of the bismuth sodium strontium cerium doped potassium sodium niobate-based ceramic wafer were tested, as shown in Figure 7 and Figure 8. . The results show that the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramics have excellent remanent polarization and coercive field, as well as high strain value and inverse piezoelectric constant;

7 The annealing curve of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic wafer was tested by the d ₃₃ piezoelectric tester (ZJ-3A), as shown in Figure 9. The results show that: bismuth sodium strontium zirconate doped potassium sodium niobate ceramics have excellent thermodynamic stability;

The bismuth, sodium and strontium zirconate doped potassium and sodium niobate-based ceramics prepared by the method of the present invention have relatively dense crystal grains and larger crystal grain sizes, so that the sintering activity is improved and the sintering effect is better. The density of bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramics is higher at lower sintering temperature (~1090 °C). The bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic has high piezoelectric constant d ₃₃ and electromechanical coupling coefficient k _p , the highest piezoelectric constant d ₃₃ is 470pC/N, and the highest electromechanical coupling coefficient k _p is 0.56.

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

1 The bismuth, sodium and strontium zirconate doped potassium and sodium niobate-based ceramic materials can effectively improve the piezoelectric properties and dielectric properties of the potassium and sodium niobate-based materials;

2. Polarization at a lower temperature is conducive to full polarization of bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramics, maximizing its piezoelectric properties and dielectric properties, and meeting the needs of industrial production.

Description of drawings

FIG. 1 is the X-ray diffraction pattern of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic materials with different contents in Examples 1-4.

FIG. 2 is a scanning electron microscope (SEM) photograph of the sodium bismuth zirconate strontium doped potassium sodium niobate-based ceramic of the sample of Example 2. FIG.

FIG. 3 is a piezoelectric force microscope (PFM) photograph of the sodium bismuth zirconate doped potassium sodium niobate-based ceramic of the sample of Example 2. FIG.

4 shows the d ₃₃ and K _p of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic materials with different contents in Examples 1-4.

5 is the high temperature dielectric temperature curves of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic materials with different contents in Examples 1-4.

6 is the low temperature dielectric temperature curves of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic materials with different contents in Examples 1-4.

FIG. 7 is a hysteresis loop diagram of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic material of the sample of Example 2. FIG.

FIG. 8 is a uniaxial strain curve diagram of the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic material of the sample of Example 2. FIG.

FIG. 9 is an annealing curve diagram of bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic materials with different contents in Examples 1-4.

Detailed ways

The present invention will be specifically described by the following examples. It is necessary to point out that this example is only used to further illustrate the present invention, and should not be construed as a limitation on the protection scope of the present invention. Those skilled in the art can Some non-essential improvements and adjustments are made to the content of the invention.

Example 1:

(1) Preparation of potassium sodium niobate-based ceramic powder by solid-phase method

The raw materials were divided according to the general formula (K _0.48 Na _0.52 )(Nb _0.97 Sb _0.03 )O ₃ -0.05(Bi _0.5 Na _0.5 )ZrO ₃

-0.0015Fe ₂ O ₃ ( x = 0.0, No. 1 ^# ), weighed and batched, placed in a urethane ball mill jar, used anhydrous ethanol as the dispersing medium, and ball-milled with a planetary ball mill for 8 to 24 hours at a rotational speed of 150 At ~250rpm, bake for 1 to 2 hours under a baking lamp, then heat up to 850°C in a programmed temperature box furnace, and keep the temperature for 6 hours to obtain potassium sodium niobate-based ceramic powder.

(2) Granulation and tableting

A polyvinyl alcohol solution with a concentration of 5~10wt% is added to the above-mentioned dried powder, and it is fully mixed, and then granulated, and then pressed to a diameter of 10~12 mm and a thickness of 0.8~1.2mm under the pressure of 10~15 MPa. bismuth sodium strontium zirconate doped potassium sodium niobate based ceramic discs.

(3) Debinding and sintering

The above-mentioned potassium and sodium niobate-based ceramic discs are degummed at a temperature of 800-900 DEG C, and then sintered at a temperature of 1050-1150 DEG C for 3-5 hours to prepare bismuth sodium strontium zirconate-doped potassium sodium niobate-based ceramic discs.

(4) Polarized by silver

The bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic disc obtained after sintering is brushed with silver paste with a concentration of 5-15wt%, and then sintered at a temperature of 600-700°C for 10-15 minutes to prepare a sample. The sample was polarized in a silicone oil bath at 20~80℃, the polarization field strength was 3~5 kV/mm, and the pressure holding time was 5~30min, to make 1 ^# bismuth sodium strontium zirconate doped potassium sodium niobate base ceramics.

Example 2:

(1) Preparation of potassium sodium niobate-based ceramic powder by solid-phase method

The raw materials were prepared according to the general formula (K _0.48 Na _0.52 )(Nb _0.97 Sb _0.03 )O ₃ -0.05Sr _0.1 (Bi _0.5 Na _0.5 ) _0.9 ZrO ₃

-0.0015Fe ₂ O ₃ ( x = 0.1, No. 2 ^# ) was weighed and batched, placed in a polyurethane ball mill, and anhydrous ethanol was used as the dispersion medium, and after 8~24 hours of ball milling with a planetary ball mill, the rotational speed was 150~ Bake at 250 rpm for 1 to 2 hours under a baking lamp, and then heat up to 850° C. in a programmed temperature box furnace, and keep the temperature for 6 hours to obtain potassium sodium niobate-based ceramic powder.

(2) Granulation and tableting

A polyvinyl alcohol solution with a concentration of 5~10wt% is added to the above-mentioned dried powder, and it is fully mixed, and then granulated, and then pressed to a diameter of 10~12 mm and a thickness of 0.8~1.2mm under the pressure of 10~15 MPa. bismuth sodium strontium zirconate doped potassium sodium niobate based ceramic discs.

(3) Debinding and sintering

The above-mentioned potassium and sodium niobate-based ceramic discs are degummed at a temperature of 800-900 DEG C, and then sintered at a temperature of 1050-1150 DEG C for 3-5 hours to prepare bismuth sodium strontium zirconate-doped potassium sodium niobate-based ceramic discs.

(4) Polarized by silver

The bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic disc obtained after sintering is brushed with silver paste with a concentration of 5-15wt%, and then sintered at a temperature of 600-700°C for 10-15 minutes to prepare a sample. The sample was polarized in a silicone oil bath at 20-80 °C, the polarization field strength was 3-5 kV/mm, and the pressure holding time was 5-30 min to prepare 2 ^# bismuth sodium strontium zirconate doped potassium sodium niobate base ceramics.

Example 3:

(1) Preparation of potassium sodium niobate-based ceramic powder by solid-phase method

The raw materials were prepared according to the general formula (K _0.48 Na _0.52 )(Nb _0.97 Sb _0.03 )O ₃ -0.05Sr _0.15 (Bi _0.5 Na _0.5 ) _0.85 ZrO ₃

-0.0015Fe ₂ O ₃ ( x = 0.15, No. 3 ^# ) was weighed and batched, placed in a urethane ball mill tank, and anhydrous ethanol was used as the dispersion medium, and after 8~24 hours of ball milling with a planetary ball mill, the rotational speed was 150~ Bake at 250 rpm for 1 to 2 hours under a baking lamp, and then heat up to 850° C. in a programmed temperature box furnace, and keep the temperature for 6 hours to obtain potassium sodium niobate-based ceramic powder.

(2) Granulation and tableting

A polyvinyl alcohol solution with a concentration of 5~10wt% is added to the above-mentioned dried powder, and it is fully mixed, and then granulated, and then pressed to a diameter of 10~12 mm and a thickness of 0.8~1.2mm under the pressure of 10~15 MPa. bismuth sodium strontium zirconate doped potassium sodium niobate based ceramic discs.

(3) Debinding and sintering

The above-mentioned potassium and sodium niobate-based ceramic discs are degummed at a temperature of 800-900 DEG C, and then sintered at a temperature of 1050-1150 DEG C for 3-5 hours to prepare bismuth sodium strontium zirconate-doped potassium sodium niobate-based ceramic discs.

(4) Polarized by silver

The bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic disc obtained after sintering is brushed with silver paste with a concentration of 5-15wt%, and then sintered at a temperature of 600-700°C for 10-15 minutes to prepare a sample. The sample was polarized in a silicone oil bath at 20-80 °C, the polarization field strength was 3-5 kV/mm, and the pressure holding time was 5-30 min to prepare 3 ^# bismuth sodium strontium zirconate doped potassium sodium niobate base ceramics.

Example 4:

(1) Preparation of potassium sodium niobate-based ceramic powder by solid-phase method

The raw materials were prepared according to the general formula (K _0.48 Na _0.52 )(Nb _0.97 Sb _0.03 )O ₃ -0.05Sr _0.3 (Bi _0.5 Na _0.5 ) _0.7 ZrO ₃

-0.0015Fe ₂ O ₃ ( x = 0.3, No. 4 ^# ) was weighed and batched, placed in a polyurethane ball mill tank, and anhydrous ethanol was used as the dispersion medium, and after 8~24 hours of ball milling with a planetary ball mill, the rotational speed was 150~ Bake at 250 rpm for 1 to 2 hours under a baking lamp, and then heat up to 850° C. in a programmed temperature box furnace, and keep the temperature for 6 hours to obtain potassium sodium niobate-based ceramic powder.

(2) Granulation and tableting

A polyvinyl alcohol solution with a concentration of 5~10wt% is added to the above-mentioned dried powder, and it is fully mixed, and then granulated, and then pressed to a diameter of 10~12 mm and a thickness of 0.8~1.2mm under the pressure of 10~15 MPa. bismuth sodium strontium zirconate doped potassium sodium niobate based ceramic discs.

(3) Debinding and sintering

The above-mentioned potassium and sodium niobate-based ceramic discs are degummed at a temperature of 800-900 DEG C, and then sintered at a temperature of 1050-1150 DEG C for 3-5 hours to prepare bismuth sodium strontium zirconate-doped potassium sodium niobate-based ceramic discs.

(4) Polarized by silver

The bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic disc obtained after sintering is brushed with silver paste with a concentration of 5-15wt%, and then sintered at a temperature of 600-700°C for 10-15 minutes to prepare a sample. The sample was polarized in a silicone oil bath at 20-80 °C, the polarization field strength was 3-5 kV/mm, and the pressure holding time was 5-30 min to prepare 4 ^# bismuth sodium zirconate strontium doped potassium sodium niobate base ceramics.

Claims (3)

1. A sodium bismuth zirconate strontium doped potassium sodium niobate based piezoelectric ceramic material and a preparation method thereof are characterized in that the preparation process comprises the following steps:

(1) preparation of potassium sodium niobate based ceramic powder by solid phase method

The raw materials are respectively expressed by the general formula (K)_0.48Na_0.52)(Nb_0.97Sb_0.03)O₃-0.05Sr _x (Bi_0.5Na_0.5) _x(1-)ZrO₃

-0.0015Fe₂O₃(whereinxRepresents Sr replacing Bi_0.5Na_0.5With a range of values for the mole fraction of (c): 0.0-0 ≤xLess than or equal to 0.3; the doping elements are added by taking oxides or carbonates as raw materials), weighing and proportioning, putting the mixture into a polyurethane ball milling tank, taking absolute ethyl alcohol as a dispersion medium, ball milling the mixture for 8 to 24 hours by using a planetary ball mill, baking the mixture for 1 to 2 hours under a baking lamp at the rotating speed of 150 to 250rpm, then heating the mixture to 850 ℃ in a program temperature control box type furnace, and preserving the heat for 6 hours to obtain the potassium-sodium niobate-based ceramic powder

(2) Granulating and tabletting

Adding 5-10 wt% polyvinyl alcohol solution into the dried powder, fully mixing, granulating, and pressing under the pressure of 10-15 MPa to obtain the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic wafer with the diameter of 10-12 mm and the thickness of 0.8-1.2 mm

(3) Binder removal sintering

Removing glue from the potassium sodium niobate-based ceramic wafer at the temperature of 800-900 ℃, and sintering at the temperature of 1050-1150 ℃ for 3-5 hours to prepare the bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic wafer

(4) Is polarized by silver

Brushing silver paste with the concentration of 5-15 wt% on the sintered bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic wafer, sintering at the temperature of 600-700 ℃ for 10-15 minutes to prepare a sample, polarizing the sample in a silicon oil bath at the temperature of 20-80 ℃, and keeping the polarization field strength at 3-5 kV/mm for 5-30 min to prepare the bismuth sodium strontium zirconate doped potassium sodium niobate-based piezoelectric ceramic.

2. The sodium bismuth zirconate strontium doped potassium sodium niobate-based ceramic material of claim 1, wherein the ceramic material is represented by the general formula (K)_0.48Na_0.52)(Nb_0.97Sb_0.03)O₃-0.05Sr _x (Bi_0.5Na_0.5) _x(1-)ZrO₃-0.0015Fe₂O₃，0.0≤ x≤ 0.3。

3. The bismuth sodium strontium zirconate doped potassium sodium niobate-based ceramic material as claimed in claim 2 obtains excellent piezoelectric performance (piezoelectric constant) under the poling method as claimed in claim 1d ₃₃ 370 to 475 pC/N, electromechanical coupling coefficientk _p 0.47 to 0.56, residual polarizationP _r : 19~24 μC/cm²Coercive fieldE _c : 7.5~9.0 kV/cm)。

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