阅读说明：本技术 一种氮、铌酸钾双掺杂无铅压电陶瓷及其制备方法 (Nitrogen and potassium niobate double-doped lead-free piezoelectric ceramic and preparation method thereof ) 是由 钟日城 于 2020-07-27 设计创作，主要内容包括：本发明涉及一种氮、铌酸钾双掺杂无铅压电陶瓷及其制备方法,所述压电陶瓷经过球磨煅烧合成,(Bi<Sub>0.5</Sub>Na<Sub>0.5</Sub>)TiO<Sub>3</Sub>-BaTiO<Sub>3</Sub>合成原料为：Bi<Sub>2</Sub>O<Sub>3</Sub>、Ba<Sub>2</Sub>CO<Sub>3</Sub>、Na<Sub>2</Sub>CO<Sub>3</Sub>、TiO<Sub>2</Sub>,KNbO<Sub>3</Sub>合成原料为：K<Sub>2</Sub>CO<Sub>3</Sub>、Nb<Sub>2</Sub>O<Sub>5</Sub>,氮源为：CH<Sub>4</Sub>N<Sub>2</Sub>O、CH<Sub>4</Sub>N<Sub>2</Sub>S,通过调节铌酸钾、氮合成原料比例,将N、KNbO<Sub>3</Sub>引入具有四方结构的(Bi<Sub>0.5</Sub>Na<Sub>0.5</Sub>)TiO<Sub>3</Sub>-BaTiO<Sub>3</Sub>中,利用结构相似性,保持热稳定的压电性能,促进BNT基组合物的铁电和压电性能,本发明所制备的双掺杂无铅压电陶瓷具有稳定的晶格结构和铁电有序有助于压电的出色热稳定性,为(Bi<Sub>0.5</Sub>Na<Sub>0.5</Sub>)TiO<Sub>3</Sub>-BaTiO<Sub>3</Sub>基压电陶瓷性能提升提供了一种新的解决办法。(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) 0.5 Na 0.5 )TiO 3 ‑BaTiO 3 The synthetic raw materials are as follows: bi 2 O 3 、Ba 2 CO 3 、Na 2 CO 3 、TiO 2 ，KNbO 3 The synthetic raw materials are as follows: k 2 CO 3 、Nb 2 O 5 The nitrogen source is:CH 4 N 2 O、CH 4 N 2 s, N, KNbO is prepared by adjusting the ratio of potassium niobate to nitrogen synthetic raw materials 3 Introduction of (Bi) having a tetragonal structure 0.5 Na 0.5 )TiO 3 ‑BaTiO 3 In 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) 0.5 Na 0.5 )TiO 3 ‑BaTiO 3 The performance improvement of the base piezoelectric ceramic provides a new solution.)

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:

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.

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.

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