CN111807833A

CN111807833A - Nitrogen and potassium niobate double-doped lead-free piezoelectric ceramic and preparation method thereof

Info

Publication number: CN111807833A
Application number: CN202010730046.4A
Authority: CN
Inventors: 钟日城
Original assignee: Hangzhou Xuekang New Material Co ltd
Current assignee: Hangzhou Xuekang New Material Co ltd
Priority date: 2020-07-27
Filing date: 2020-07-27
Publication date: 2020-10-23

Abstract

The invention relates to a nitrogen and potassium niobate double-doped lead-free piezoelectric ceramic and a preparation method thereof, wherein the piezoelectric ceramic is synthesized by ball milling and calcining, (Bi)_0.5Na_0.5)TiO₃‑BaTiO₃The synthetic raw materials are as follows: bi₂O₃、Ba₂CO₃、Na₂CO₃、TiO₂，KNbO₃The synthetic raw materials are as follows: k₂CO₃、Nb₂O₅The nitrogen source is:CH₄N₂O、CH₄N₂s, N, KNbO is prepared by adjusting the ratio of potassium niobate to nitrogen synthetic raw materials₃Introduction of (Bi) having a tetragonal structure_0.5Na_0.5)TiO₃‑BaTiO₃In the method, by utilizing the structural similarity, the thermally stable piezoelectric performance is maintained, and the ferroelectric and piezoelectric performance of the BNT-based composition is promoted, the prepared double-doped lead-free piezoelectric ceramic has stable lattice structure and ferroelectric order, contributes to excellent piezoelectric thermal stability, and is (Bi)_0.5Na_0.5)TiO₃‑BaTiO₃The performance improvement of the base piezoelectric ceramic provides a new solution.

Description

Nitrogen and potassium niobate double-doped lead-free piezoelectric ceramic and preparation method thereof

Technical Field

The invention belongs to the field of piezoelectric ceramics, and particularly relates to nitrogen and potassium niobate double-doped (Bi) with high-temperature stability_0.5Na_0.5)TiO₃-BaTiO₃Lead-free piezoelectric ceramics and a preparation method thereof.

Background

Piezoelectric ceramics are widely used as sensors and actuators and are an integral part of modern electronic applications. The toxicity of the commercial lead-based piezoelectric materials currently in use has led to a great deal of effort to find lead-free alternatives. The main class of lead-free piezoelectric materials includes K_0.5Na_0.5NbO₃(KNN)，BaTiO₃(BT) and (Bi)_0.5Na0.5)TiO₃(BNT), and the like. Because they have a stable mechanical quality factor against vibration speed, BNT-based solid solutions exhibit good piezoelectric properties, excellent reproducibility, and a high maximum dielectric constant temperature (Tm 300 ℃), and show substitution for lead-based Pb (Zr, Ti) O₃Has wide prospect. However, a key factor limiting the use of BNT-BT is the thermal depolarization of BNT itself, which leads to the disappearance of macroscopic piezoelectric behavior, thereby reducing thermal stability and limiting operating temperature. Therefore, maintaining a high dielectric constant (Td) while increasing the piezoelectric constant (d33) of BNT-based ceramics is a promising approach to open lead-free piezoelectric ceramic applications. Numerous attempts have been made to enhance the Td of BNT based solid solutions, including chemical doping and complex formation. For example, ZnO inclusions can control thermal depolarization of BNT-based ceramics. In addition, the doping of manganese and cobalt is believed to be beneficial in increasing the thermal depolarization temperature of the BNT-based composite. However, although these studies improved thermal stability, the piezoelectric constant (d33) did not improve.

KNbO with square structure₃(KN) is a strong ferroelectric with large spontaneous polarization (Ps 1/4)₃0μC/cm²) And high curie temperature (TC1/4 ═ 434 ℃).

KN is currently commonly incorporated into pure BNT or BNT-BT based compositions around a pure phase boundary (MPB), however, despite the significant improvement in piezoelectric or dielectric response at room temperature, their significant lattice difference with KN leads to a dramatic drop in thermal depolarization behavior.

Disclosure of Invention

The invention aims to solve the problem of the conventional piezoelectric ceramicsLow conductivity and low thermal stability, and provides a nitrogen-potassium niobate double-doped (Bi) with high-temperature stability_0.5Na_0.5)TiO₃-BaTiO₃Lead-free piezoelectric ceramics and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a dual-doped leadless piezoelectric ceramic prepared from potassium niobate (KNbO)₃) Nitrogen (N) doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Synthesized by ball milling and calcining, (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The synthetic raw materials are as follows: bi₂O₃、Ba₂CO₃、Na₂CO₃、TiO₂，KNbO₃The synthetic raw materials are as follows: k₂CO₃、Nb₂O₅The nitrogen source is: CH (CH)₄N₂O、CH₄N₂S, N, KNbO is prepared by adjusting the ratio of potassium niobate to nitrogen synthetic raw materials₃Introduction of (Bi) having a tetragonal structure_0.5Na_0.5)TiO₃-BaTiO₃The ferroelectric and piezoelectric properties of the BNT-based compositions are promoted by utilizing structural similarity to maintain thermally stable piezoelectric properties. N, KNbO₃The influence of doping modification on the dynamic behavior of PNRs and the generation of domain wall energy barrier can ensure that the d33 value of the double-doped lead-free piezoelectric ceramic is stable in a wide temperature range

Preferably, (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Middle (Bi)_0.5Na_0.5)TiO₃As a matrix, (Bi)_0.5Na_0.5)TiO₃、BaTiO₃The mol percentage content is as follows: 80-90% and 10-20%.

Preferably, the nitrogen source is introduced first with KNbO₃Synthesis of starting Material K₂CO₃、Nb₂O₅Composite ball milling treatment of nitrogen element N₂p and O₃P hybridization promotion of KNbO₃The forbidden band width is reduced, and KNbO is adjusted₃Size formation, KNbO induction₃Into (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The internal part of the crystal lattice influences the reaction energy barrier,resulting in good piezoelectric effect.

The invention also provides a preparation method of the double-doped lead-free piezoelectric ceramic, which comprises the following steps:

1) taking Bi₂O₃、Ba₂CO₃、Na₂CO₃、TiO₂Mixing, ball milling and heat treatment;

2) will CH₄N₂O、CH₄N₂S is added to K₂CO₃、Nb₂O₅Mixing and ball milling;

3) mixing the product of the step 1) and the product of the step 2), and carrying out ball milling;

4) adding the product obtained in the step 3) into an alcohol solution, stirring, performing ultrasonic treatment, and atomizing to prepare powder;

5) and (3) calcining the product obtained in the step 4) in a tubular furnace in Ar gas atmosphere, tabletting, degumming and sintering after calcining.

Preferably, the ball milling time in the step 1) is 1-2 h, and the heat treatment temperature is 100-150 ℃. Bi₂O₃、Ba₂CO₃、Na₂CO₃、TiO₂The molar weight of (A) is: 1 to 5mmol, 2 to 3mmol, 3 to 5mmol, and 3 to 6 mmol.

Preferably, the ball milling time in the step 2) is 12-24H, H₄N₂O、CH₄N₂S、K₂CO₃、Nb₂O₅The molar weight is as follows: 0.3 to 0.45mmol, 0.14 to 0.32mmol, 0.1 to 0.5mmol, 0.2 to 0.6 mmol.

Preferably, the product obtained in the step 4) is stirred for 1-2 hours, the ultrasonic time is 6-8 hours, and atomized to prepare powder.

Preferably, the calcining temperature of the tubular furnace in the step 5) is set as follows: heating to 300 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 650 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 860 ℃ within 20 minutes, preserving heat for 3 hours, and then cooling to room temperature. The calcination at different temperatures can enhance the surface activity of the material, and is beneficial to the formation of nano-scale mixed materials

Preferably, the binder used in the tabletting in the step 5) is: the polyvinyl butyral has a cylindrical tabletting shape and a thickness of: 05-0.8 mm, the diameter is 8-11 mm, and the degumming temperature is: the degumming time is 24 hours at the temperature of 600 ℃.

Preferably, the sintering temperature in step 5) is set as follows: heating to 300 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 650 ℃ within 20 minutes, preserving heat for 1 hour, heating to 1150 ℃ within 1 hour, preserving heat for 4 hours, and cooling to room temperature.

Compared with other photocatalysts, the invention has the following advantages:

1)N、KNbO₃the energy barrier is reduced by double-element doping, and the thermal stability temperature range of the double-doped lead-free piezoelectric ceramic is widened.

2) The stable lattice structure and ferroelectric order of the double-doped lead-free piezoelectric ceramic contribute to the excellent thermal stability of the piezoelectric.

3) The piezoelectric coefficient is still kept around 187pC/N at the annealing temperature of 190 ℃, and good piezoelectric performance is kept.

4) The nitrogen element promotes the further promotion of the synergistic effect, and is beneficial to meeting the market demand index.

Drawings

FIG. 1 shows a nitrogen and potassium niobate double-doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃XRD pattern of the lead-free piezoelectric ceramic;

FIG. 2 shows the nitrogen and potassium niobate double doping (Bi) at different annealing temperatures_0.5Na_0.5)TiO₃-BaTiO₃A lead-free piezoelectric ceramic piezoelectric curve;

FIG. 3 shows a nitrogen and potassium niobate double-doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Polarization curve diagram of leadless piezoelectric ceramics.

Detailed Description

The invention will now be further described by way of examples

Example 1:

1) taking Bi₂O₃、Ba₂CO₃、Na₂CO₃、TiO₂Mixing, ball milling for 1 hr, and heat treatment at 130 deg.c. Bi₂O₃、Ba₂CO₃、Na₂CO₃、TiO₂The molar weight of (A) is: 3mmol, 5mmol, 12 mmol. (ii) a

2) Will CH₄N₂O、CH₄N₂S is added to K₂CO₃、Nb₂O₅Mixing, ball milling for 12 hr, K₂CO₃、Nb₂O₅The molar weight is as follows: 0.5mmol, 0.6 mmol;

3) mixing the product of the step 2) with the product of the step 3), and carrying out ball milling;

4) adding the product obtained in the step 3) into an alcohol solution, stirring, performing ultrasonic treatment, and atomizing to prepare powder, wherein the stirring time is 2 hours, and the ultrasonic time is 8 hours;

5) and (3) calcining the product obtained in the step 4) in a tubular furnace at Ar gas atmosphere, tabletting, degumming and sintering, wherein the calcining temperature of the tubular furnace is set as follows: heating to 300 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 650 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 860 ℃ within 20 minutes, preserving heat for 3 hours, cooling to room temperature, wherein the binder used for tabletting is as follows: the polyvinyl butyral has a cylindrical tabletting shape and a thickness of: 0.8mm, diameter 11mm, degumming temperature: the degumming time is 24 hours at the temperature of 600 ℃, and the sintering temperature is set as follows: heating to 300 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 650 ℃ within 20 minutes, preserving heat for 1 hour, heating to 1150 ℃ within 1 hour, preserving heat for 4 hours, and cooling to room temperature.

6) The prepared nitrogen and potassium niobate are doubly doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃XRD scanning of the lead-free piezoelectric ceramic shows that diffraction peaks, namely nitrogen and potassium niobate diffraction peaks, are formed on the (101) and (211) interfaces, and the method shows that the nitrogen and potassium niobate double-doped (Bi) can be successfully prepared by the method_0.5Na_0.5)TiO₃-BaTiO₃Leadless piezoelectric ceramic

7) The prepared nitrogen and potassium niobate are doubly doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramic is subjected to different temperature piezoelectric tests, and the piezoelectric coefficient reaches 178PC/N at 150 ℃, so that the lead-free piezoelectric ceramic has excellent piezoelectric performance.

Example 2: to step 5) oneDouble doping of nitrogen and potassium niobate (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The temperature of the lead-free piezoelectric ceramic is regulated, and the calcining temperature of the tube furnace is set as follows: heating to 150 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 600 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 800 ℃ within 20 minutes, preserving heat for 3 hours, cooling to room temperature, wherein the binder used for tabletting is as follows: the polyvinyl butyral has a cylindrical tabletting shape and a thickness of: 0.8mm, diameter 11mm, degumming temperature: the degumming time is 24 hours at the temperature of 600 ℃, and the sintering temperature is set as follows: heating to 200 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 620 ℃ within 20 minutes, preserving heat for 1 hour, heating to 980 ℃ within 1 hour, preserving heat for 4 hours, and cooling to room temperature. The other steps are all identical to those of example 1.

Example 3: double doping of nitrogen and potassium niobate (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The proportion of the raw materials for synthesizing the leadless piezoelectric ceramics is adjusted, and the nitrogen and the potassium niobate are doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Among lead-free piezoelectric ceramics, KNbO₃、N、(Bi_0.5Na_0.5)TiO₃-BaTiO₃The mole percentages are 1%, 0.5%, 98.5%, and the other steps are all identical to example 1.

Example 4: double doping of nitrogen and potassium niobate (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The proportion of the raw materials for synthesizing the leadless piezoelectric ceramics is adjusted, and the nitrogen and the potassium niobate are doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Among lead-free piezoelectric ceramics, KNbO₃、N、(Bi_0.5Na_0.5)TiO₃-BaTiO₃The mole percentages are 10%, 1%, 89%, and the other steps are all identical to those of example 1.

When the nitrogen and the potassium niobate are double doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Among lead-free piezoelectric ceramics, KNbO₃、N、(Bi_0.5Na_0.5)TiO₃-BaTiO₃When the mol percentage is in the range of 1-10%, 0.5-1% and 89-98.5%, the doping effect of nitrogen and potassium niobate is obvious,the piezoelectric coefficient reaches 176PC/N, and is obviously reduced compared with the synergistic effect of nitrogen and potassium niobate in different proportions in other embodiments, the piezoelectric coefficient is only 102PC/N and is obviously lower than KNbO₃、N、(Bi_0.5Na_0.5)TiO₃-BaTiO₃The mol percentage is as follows: 1% -10%, 0.5% -1%, 89% -98.5% of nitrogen and potassium niobate double doping (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The piezoelectric coefficient of the lead-free piezoelectric ceramic.

Application test

Test example 1: nitrogen, potassium niobate double doping (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Piezoelectric test of leadless piezoelectric ceramics

1) Curve 1 obtained in example 1 was taken to be doubly doped with nitrogen and potassium niobate (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Leadless piezoelectric ceramic, curve 2 common mixed nitrogen, potassium niobate double doping (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Lead-free piezoelectric ceramic, curve 3 undoped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramics were subjected to a piezoelectric test.

As shown in FIG. 3, all polarization curves exhibit asymmetric characteristics, i.e., double doping of nitrogen and potassium niobate (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramic has the largest interval range, which shows that the double doping has further promotion effect on coupling into ferroelectric domain.

Test example 2: is double doped with nitrogen and potassium niobate (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Leadless piezoelectric ceramic, potassium niobate doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Leadless piezoelectric ceramic, (Bi)_0.5Na_0.5)TiO₃-BaTiO₃And (3) carrying out annealing tests on the lead-free piezoelectric ceramic at different temperatures.

1) The nitrogen and potassium niobate prepared in example 1 were doubly doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Leadless piezoelectric ceramic and potassium niobate double-doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Leadless piezoelectric ceramic, undoped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramic is subjected to piezoelectric constant test, the piezoelectric constant is rapidly reduced to about 0 after the annealing temperature exceeds 180 ℃, the excellent piezoelectric constant is shown after annealing at 100-180 ℃, and the doping stability of nitrogen and potassium niobate can be improved by annealing at 100-180 ℃.

Test example 3: the test is that in example 1, the nitrogen and the potassium niobate are doubly doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The piezoelectric coefficient of y1 (d33), the dielectric constant of y2 r, the residual polarization of y3 Pr and the electrostrictive coefficient of y 4Q 33 of the lead-free piezoelectric ceramic at room temperature are tested.

1) The nitrogen and potassium niobate prepared in example 1 were doubly doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramic is subjected to double doping of piezoelectric coefficient, dielectric constant, residual polarization, electrostrictive coefficient and nitrogen and potassium niobate (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The piezoelectric coefficient of the lead-free piezoelectric ceramic is 147pC/N, which is higher than the piezoelectric coefficient of 135pC/N of other single piezoelectric ceramics. The dielectric constant, the residual polarization and the electrostriction further prove that the nitrogen and the potassium niobate are doubly doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramic has good thermal stability for high-temperature piezoelectric applications.

The foregoing detailed description is exemplary only, and is not intended to limit the scope of the patent, as defined by the appended claims; any equivalent alterations or modifications made according to this patent are intended to fall within the scope of this patent.

Claims

1. Nitrogen and potassium niobate double-doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramic is characterized in that: the lead-free piezoelectric ceramic is made of potassium niobate (KNbO)₃) Nitrogen (N) doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃Synthesized by ball milling and calcining, the (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The synthetic raw materials are as follows: bi₂O₃、BaCO₃、Na₂CO₃、TiO₂Said KNbO₃The synthetic raw materials are as follows: k₂CO₃、Nb₂O₅The nitrogen source is: CH (CH)₄N₂O、CH₄N₂S。

2. The nitrogen and potassium niobate double-doped (Bi) according to claim 1_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramic is characterized in that (Bi) is_0.5Na_0.5)TiO₃-BaTiO₃Middle (Bi)_0.5Na_0.5)TiO₃As a matrix, (Bi)_0.5Na_0.5)TiO₃、BaTiO₃The mol percentage content is as follows: 80-90% and 10-20%.

3. The nitrogen and potassium niobate double-doped (Bi) according to claim 1_0.5Na_0.5)TiO₃-BaTiO₃The lead-free piezoelectric ceramic is characterized in that the nitrogen source CH₄N₂O、CH₄N₂S, first with KNbO₃Synthesis of starting Material K₂CO₃、Nb₂O₅And (5) performing composite ball milling treatment.

4. Nitrogen and potassium niobate double-doped (Bi)_0.5Na_0.5)TiO₃-BaTiO₃The preparation method of the lead-free piezoelectric ceramic is characterized by comprising the following steps: the method comprises the following steps:

5. The nitrogen and potassium niobate double-doped (Bi) according to claim 4_0.5Na_0.5)TiO₃-BaTiO₃The preparation method of the lead-free piezoelectric ceramic is characterized by comprising the following steps: the ball milling time in the step 1) is 1-2 h, and the heat treatment temperature is 100-150 ℃; bi₂O₃、Ba₂CO₃、Na₂CO₃、TiO₂The molar weight of (A) is: 1 to 5mmol, 2 to 3mmol, 3 to 5mmol, and 3 to 6 mmol.

6. The nitrogen and potassium niobate double-doped (Bi) according to claim 4_0.5Na_0.5)TiO₃-BaTiO₃The preparation method of the lead-free piezoelectric ceramic is characterized in that the ball milling time in the step 2) is 12-24 hours, and CH₄N₂O、CH₄N₂S、K₂CO₃、Nb₂O₅The molar weight is as follows: 0.3 to 0.45mmol, 0.14 to 0.32mmol, 0.1 to 0.5mmol, 0.2 to 0.6 mmol.

7. The nitrogen and potassium niobate double-doped (Bi) according to claim 4_0.5Na_0.5)TiO₃-BaTiO₃The preparation method of the lead-free piezoelectric ceramic is characterized by comprising the following steps: stirring time in the step 4) is 1-2 hours, ultrasonic time is 6-8 hours, and atomization is performed to prepare powder.

8. The nitrogen and potassium niobate double-doped (Bi) according to claim 4_0.5Na_0.5)TiO₃-BaTiO₃The preparation method of the lead-free piezoelectric ceramic is characterized in that the calcining temperature of the tubular furnace in the step 5) is set as follows: heating to 150-300 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 600-650 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 800-860 ℃ within 20 minutes, and preserving heat for 3After that, it was cooled to room temperature.

9. The nitrogen and potassium niobate double-doped (Bi) according to claim 4_0.5Na_0.5)TiO₃-BaTiO₃The preparation method of the lead-free piezoelectric ceramic is characterized by comprising the following steps: the binder used in tabletting in the step 5) is as follows: the polyvinyl butyral is cylindrical in tabletting shape, the thickness is 0.5-0.8 mm, the diameter is 8-11 mm, the degumming temperature is 400-600 ℃, and the degumming time is 24 hours.

10. The nitrogen and potassium niobate double-doped (Bi) according to claim 4_0.5Na_0.5)TiO₃-BaTiO₃The preparation method of the lead-free piezoelectric ceramic is characterized in that the sintering temperature in the step 5) is set as follows: heating to 200-300 ℃ within 20 minutes, preserving heat for 30 minutes, heating to 620-650 ℃ within 20 minutes, preserving heat for 1 hour, heating to 980-1150 ℃ within 1 hour, preserving heat for 4 hours, and cooling to room temperature.