CN101648807A - Calcium barium zirconate titanate base piezoceramics and preparation method thereof - Google Patents

Abstract

The invention discloses barium calcium zirconate titanate-based piezoelectric ceramics and a preparation method thereof. The general chemical composition formula of barium calcium zirconate titanate based piezoelectric ceramics is: (1－x－y)BaTiO ₃ －xCaTiO ₃ －yBaZrO ₃ , where: 0<x<0.5, 0<y<0.5; both x and y is the mole fraction. Barium carbonate, calcium carbonate, titanium dioxide, zirconium dioxide, according to the stoichiometric ratio (1-x-y) BaTiO ₃ -xCaTiO ₃ -yBaZrO ₃ (0<x<0.5, 0<y<0.5; x, y are both Mole fraction) ingredients, after ball milling, calcination, secondary ball milling, granulation, molding, debinding, high temperature sintering and other processes, finally prepare barium calcium zirconate titanate based piezoelectric ceramics with high voltage properties. The method of the invention greatly improves the piezoelectric performance of the lead-free piezoelectric ceramic system, improves the process stability of the material, and makes the lead-free piezoelectric ceramic of the barium titanate system reach the practical level from two aspects of composition and process.

Description

Barium calcium zirconate titanate based piezoelectric ceramics and preparation method thereof

technical field

The invention relates to a barium calcium zirconate titanate-based piezoelectric ceramic with high piezoelectric performance and a preparation method thereof, belonging to the field of electronic ceramics.

Background technique

Piezoelectric ceramics can generate strain under the action of an external electric field. At the same time, under the action of external force, piezoelectric ceramics will generate charges at the two poles, so they are widely used in transducers, micro-displacers, sensors, resonators and filters, etc. field.

Literature "Shoufu Shao, Jialiang Zhang, Zong Zhang, Peng Zheng, MingleiZhao, Jichao Li and Chunlei Wang, High piezoelectric properties and domain configuration in BaTiO ₃ ceramics obtained through the solid-state reaction route, J.Phys.D: Appl.Phys.41 (2008) 125408 "Using the traditional solid-phase synthesis method to prepare high-performance lead-free piezoelectric ceramics, the piezoelectric performance of barium titanate has been greatly improved. However, their sintering process is very complicated. High-performance barium titanate ceramics must be fired within a narrow temperature range, which seriously restricts its mass production and product process stability. The current general solution is to add other perovskite components to adjust its piezoelectric performance and process performance.

Contents of the invention

In order to overcome the problems of poor process performance of high-performance barium titanate ceramics in the prior art, the present invention provides a high-voltage barium calcium zirconate titanate-based piezoelectric ceramic, which uses calcium titanate and barium zirconate and barium titanate to composite The formation of a solid solution has greatly improved its piezoelectric performance and process performance.

The invention also provides a preparation method of the barium calcium zirconate titanate-based piezoelectric ceramic.

Technical scheme of the present invention is:

The general chemical composition formula of barium calcium zirconate titanate based piezoelectric ceramics is: (1-xy)BaTiO ₃ -xCaTiO ₃ -yBaZrO ₃ , where: 0<x<0.5, 0<y<0.5, x and y are moles Fraction.

The specific preparation method is:

(1) mix barium carbonate, calcium carbonate, titanium dioxide and zirconium dioxide according to the stoichiometric ratio as (1-xy) BaTiO ₃ -xCaTiO ₃ -yBaZrO ₃ ingredients, wherein: 0<x<0.5, 0<y<0.5;

(2) Put the material prepared in step (1) into a ball mill and mix the materials. The ball/material mass ratio is 2 to 20. The material of the ball is one of iron balls, agate balls, zirconia balls and alumina balls. , the time of ball milling is 2 to 14 hours, and the speed is 200 to 450 rpm;

(3) Pre-fire the mixed material in step (2) for 1-3 hours at a temperature of 1000-1400 ° C, take out the calcined material, grind it, and ball mill it again. The ball milling time and speed are the same as step (2), and then The powder is passed through a 40-mesh sieve, and the material of the ball and the ball/material ratio are the same as step (2);

(4) Add the powder obtained in step (3) to pure water with a mass ratio of 10-45%, a polyacrylic acid ammonia dispersant with a mass ratio of 0.2-2% and a polyvinyl alcohol binder with a mass ratio of 0.2-2% , mixed uniformly by ball milling for 1 to 3 hours to form a slurry, the ball milling speed is 50 to 300 revolutions per minute, airflow spray granulation is used to obtain barium calcium zirconate titanate powder particles with a particle diameter of 0.01 to 1 mm;

(5) Put the powder granules prepared in step (4) into a press, and press them into discs or square tablets under a pressure of 200-900 MPa;

(6) Put the disc or square sheet formed in step (5) into an oven and bake at 120°C for 1 to 6 hours to become a plain sheet, and then put the dried plain sheet in the furnace to remove the glue, and the heating rate is 25 to 500 30~90℃/h at ℃, 90~120℃/h at 500~800℃, and keep warm at 270℃, 360℃, 500℃ and 800℃ for 1~4 hours respectively, and cool with the furnace;

(7) Put the plain sheet obtained in step (6) into a sintering furnace, raise the temperature to 1200-1500°C at a rate of 2-12°C/min, keep it warm for 1-8 hours, then cool with the furnace, and take it out after sintering , coated with low-temperature silver paste, and kept at 500-800°C for 0.2-1.5 hours to make electrodes;

(8) Immerse the tile prepared in step (7) in silicone oil at 25-85°C and polarize for 10-60 minutes, with a polarization electric field of 0.1-4 kV/mm.

The beneficial effects of the present invention are: since calcium titanate and barium zirconate are used to form a solid solution with barium titanate, the influence of the preparation process on the piezoelectric performance is reduced, and a trigonal-tetragonal phase boundary is formed. Near the phase boundary, the piezoelectric performance is greatly enhanced, and at the same time, this method can effectively reduce the coercive field of piezoelectric ceramics, making the polarization process simple and easy. The invention can prepare lead-free piezoelectric ceramics with different piezoelectric and dielectric properties, so as to meet the needs of different fields; the piezoelectric ceramics have simple components, low cost, simple process flow, good repeatability, and low equipment requirements, making production The cost is low, and it is suitable for large-scale and batch production. The electrical parameter that the present invention obtains is, piezoelectric constant d ₃₃ is 200～750pC/N, plane coupling electromechanical coefficient _kp is 0.15～0.65, quality factor Q _m is 110～1400, thickness electromechanical coupling coefficient k _t is 0.20～ 0.86.

Description of drawings

Fig. 1 is the X-ray spectrum of barium calcium zirconate titanate ceramics in Example 1 of the present invention.

Fig. 2 is a scanning electron microscope image of the barium calcium zirconate titanate ceramic according to Example 2 of the present invention.

Fig. 3 is a scanning electron microscope picture of barium calcium zirconate titanate ceramic according to Example 3 of the present invention.

Detailed ways

Example 1:

With the barium carbonate whose mass percentage content is 99.9%, the calcium carbonate that the mass percentage content is 99.8%, the titanium dioxide that the mass percentage content is 98.0%, and the zirconium dioxide that the mass percentage content is 99.0%, the stoichiometric ratio is 0.76 BaTiO ₃ -0.12CaTiO ₃ -0.12BaZrO ₃ were weighed and batched. The prepared materials are put into a ball mill and mixed according to the ratio of zirconia balls:materials at 10:1, and no other medium is added during the mixing process. The time of ball milling is 6 hours, and the rotating speed is 400 rpm. The mixed material briquette is pre-fired at 1250°C for 2 hours, the calcined material is taken out and ground, and then passed through a 40-mesh sieve after ball milling for 6 hours. The ball milling speed is 400 rev/min; add the powder to its mass ratio of 32% pure water, mass ratio of 1.2% polyacrylic acid ammonia dispersant and mass ratio of 0.8% polyvinyl alcohol binder, and mix it uniformly by ball milling for 2 hours to form a material Slurry, the ball milling speed is 100 rev/min, and the air spray is used for granulation; the powder particles are put into a press, and a disc with a diameter of 15 mm and a thickness of 1.2 mm is obtained under a pressure of 450 MPa; it is put into an oven and baked at 120 ° C for 10 hours to become Then put the dried plain sheet into the furnace to remove the glue. The heating rate is 30°C/h at 25-500°C, 100°C/h at 500-800°C, and at 270°C and 360°C respectively. , 500°C and 800°C for 2 hours, then cool with the furnace; put the plain sheet after the glue is discharged into the sintering furnace, the heating rate is 5°C/min, sinter at 1350°C, and then cool with the furnace. After the sintering is completed, take it out, apply medium-temperature silver paste, keep it at 800°C for 0.5 hours to become an electrode, and polarize it in silicone oil at 25°C for 10 minutes, with a polarization electric field of 1kV/mm. The barium calcium zirconate titanate ceramic obtained by this method has a piezoelectric constant d ₃₃ of 527 pC/N, a plane coupling electromechanical coefficient k _p of 0.54, a quality factor Q _m of 721, and a thickness electromechanical coupling coefficient k _t of 0.67. Figure 1 shows the X-ray spectrum of barium calcium zirconate titanate ceramics.

Example 2:

The barium carbonate whose mass percentage content is 99.9%, the calcium carbonate whose mass percentage content is 99.8%, the titanium dioxide whose mass percentage content is 98.0%, and the zirconium dioxide whose mass percentage content is 99.0% are used to analyze the pure grade, and the stoichiometric ratio is 0.75 BaTiO ₃ -0.15CaTiO ₃ -0.1BaZrO ₃ were weighed and batched. The prepared materials are put into a ball mill and mixed according to the ratio of zirconia balls:materials at 15:1, and no other medium is added during the mixing process. The time of ball milling is 6 hours, and the rotating speed is 350 rpm. The mixed material briquette is pre-fired at 1250° C. for 2 hours. The calcined material is taken out and ground, and then ball milled for 6 hours and passed through a 40-mesh sieve. The ball milling speed is 350 rev/min; add the powder to the pure water with a mass ratio of 30%, the polyacrylic acid ammonia dispersant with a mass ratio of 1.1%, and the polyvinyl alcohol binder with a mass ratio of 0.9%, and mix it uniformly by ball milling for 2 hours to form a material Slurry, the ball milling speed is 150 rev/min, and the airflow spray granulation is adopted; the powder particles are put into the press, and the discs with a diameter of 15 mm and a thickness of 1.2 mm are obtained under a pressure of 500 MPa; put into an oven and baked at 120 ° C for 10 hours to become Then put the dried plain sheet into the furnace to remove the glue. The heating rate is 30°C/h at 25-500°C, 100°C/h at 500-800°C, and at 270°C and 360°C respectively. , 500°C and 800°C for 2 hours, then cool with the furnace; put the plain sheet after the glue is discharged into the sintering furnace, the heating rate is 10°C/min, sinter at 1400°C, and then cool with the furnace. Coat medium-temperature silver paste, keep warm at 800°C for 0.5 hours to become electrodes, and polarize in silicone oil at 25°C for 30 minutes, with a polarization electric field of 1.5kV/mm. The barium calcium zirconate titanate ceramic obtained by this method has a piezoelectric constant d ₃₃ of 673 pC/N, a plane coupling electromechanical coefficient k _p of 0.64, a quality factor Q _m of 558, and a thickness electromechanical coupling coefficient k _t of 0.77. Figure 2 shows the scanning electron microscope pictures of barium calcium zirconate titanate ceramics.

Example 3:

It is 99.9% barium carbonate, 99.8% calcium carbonate, 98.0% titanium dioxide and 99.0% zirconia of 99.0% by mass, and the stoichiometric ratio is 0.74 BaTiO ₃ -0.18CaTiO ₃ -0.08BaZrO ₃ were weighed and batched. The prepared materials are put into a ball mill and mixed according to the ratio of zirconia balls:materials at 8:1, and no other medium is added during the mixing process. The time of ball milling is 6 hours, and the rotating speed is 450 rpm. The mixed material briquette is pre-fired at 1250°C for 2 hours, the calcined material is taken out and ground, and then passed through a 40-mesh sieve after ball milling for 6 hours. The ball milling speed is 450 rpm; add the powder to its mass ratio of 40% pure water, mass ratio of 1% polyacrylic acid ammonia dispersant and mass ratio of 1% polyvinyl alcohol binder, and mix it evenly by ball milling for 2 hours to form a material Slurry, the ball milling speed is 80 rev/min, and air spray granulation is adopted; the powder particles are put into a press, and a disc with a diameter of 15 mm and a thickness of 1.2 mm is obtained under a pressure of 350 MPa; put into an oven and bake at 120 ° C for 10 hours to become Then put the dried plain sheet into the furnace to remove the glue. The heating rate is 30°C/h at 25-500°C, 100°C/h at 500-800°C, and at 270°C and 360°C respectively. , 500°C and 800°C for 2 hours, then cool with the furnace; put the plain sheet after the glue is discharged into the sintering furnace, the heating rate is 7°C/min, sinter at 1320°C, and then cool with the furnace. After the sintering is completed, take it out, apply medium-temperature silver paste, keep it at 800°C for 0.5 hours to become an electrode, and polarize it in silicone oil at 25°C for 20 minutes with a polarization electric field of 1kV/mm. The piezoelectric constant d ₃₃ of barium calcium zirconate titanate ceramics obtained by this method is 482pC/N, the plane coupling electromechanical coefficient k _p is 0.48, the quality factor Q _m is 686, and the thickness electromechanical coupling coefficient k _t is 0.59. Figure 3 shows the scanning electron microscope pictures of barium calcium zirconate titanate ceramics.

Claims (2)

1. A barium calcium zirconate titanate-based piezoelectric ceramic, characterized in that the chemical composition general formula of barium calcium zirconate titanate based piezoelectric ceramic is: (1-xy)BaTiO ₃ -xCaTiO ₃ -yBaZrO ₃ , wherein: 0 <x<0.5, 0<y<0.5, both x and y are mole fractions. 2. the preparation method of barium calcium zirconate titanate based piezoelectric ceramics as claimed in claim 1, is characterized in that preparation method is: (1) mix barium carbonate, calcium carbonate, titanium dioxide and zirconium dioxide according to the stoichiometric ratio as (1-xy) BaTiO ₃ -xCaTiO ₃ -yBaZrO ₃ ingredients, wherein: 0<x<0.5, 0<y<0.5; (2) Put the material prepared in step (1) into a ball mill and mix the materials. The ball/material mass ratio is 2 to 20. The material of the ball is one of iron balls, agate balls, zirconia balls and alumina balls. , the time of ball milling is 2 to 14 hours, and the speed is 200 to 450 rpm; (3) Pre-fire the mixed material in step (2) for 1-3 hours at a temperature of 1000-1400 ° C, take out the calcined material, grind it, and ball mill it again. The ball milling time and speed are the same as step (2), and then The powder is passed through a 40-mesh sieve, and the material of the ball and the ball/material ratio are the same as step (2); (4) Add the powder obtained in step (3) to pure water with a mass ratio of 10-45%, a polyacrylic acid ammonia dispersant with a mass ratio of 0.2-2% and a polyvinyl alcohol binder with a mass ratio of 0.2-2% , mixed uniformly by ball milling for 1 to 3 hours to form a slurry, the ball milling speed is 50 to 300 revolutions per minute, airflow spray granulation is used to obtain barium calcium zirconate titanate powder particles with a particle diameter of 0.01 to 1 mm; (5) Put the powder granules prepared in step (4) into a press, and press them into discs or square tablets under a pressure of 200-900 MPa; (6) Put the disc or square sheet formed in step (5) into an oven and bake at 120°C for 1 to 6 hours to become a plain sheet, and then put the dried plain sheet in the furnace to remove the glue, and the heating rate is 25 to 500 30~90℃/h at ℃, 90~120℃/h at 500~800℃, and keep warm at 270℃, 360℃, 500℃ and 800℃ for 1~4 hours respectively, and cool with the furnace; (7) Put the plain sheet obtained in step (6) into a sintering furnace, raise the temperature to 1200-1500°C at a rate of 2-12°C/min, keep it warm for 1-8 hours, then cool with the furnace, and take it out after sintering , coated with low-temperature silver paste, and kept at 500-800°C for 0.2-1.5 hours to make electrodes; (8) Immerse the tile prepared in step (7) in silicone oil at 25-85°C and polarize for 10-60 minutes, with a polarization electric field of 0.1-4 kV/mm.

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