阅读说明：本技术 一种三元系铌钪酸铅-铌镁酸铅-钛酸铅陶瓷及其制备方法 (Ternary-system lead scandium niobate-lead magnesium niobate-lead titanate ceramic and preparation method thereof ) 是由 郭菲菲 惠增哲 龙伟 李晓娟 方频阳 周宏桥 贾博 周峰峰 于 2019-12-25 设计创作，主要内容包括：本发明涉及一种三元系铌钪酸铅-铌镁酸铅-钛酸铅陶瓷及其制备方法,该陶瓷材料的化学式为xPb(Sc<Sub>1/2</Sub>Nb<Sub>1/2</Sub>)O<Sub>3</Sub>-yPb(Mg<Sub>1/3</Sub>Nb<Sub>2/3</Sub>)O<Sub>3</Sub>-zPbTiO<Sub>3</Sub>,其中0.1≤x≤0.28mol,0.32≤y≤0.57mol,0.33≤z≤0.40mol,且x+y+z＝1。本发明制备方法采用传统的两步固相反应法合成,通过该方法制备的陶瓷材料,其压电陶瓷压电常数d<Sub>33</Sub>可达720pC/N,径向机电耦合系数k<Sub>p</Sub>为0.65左右,厚度机电耦合系数k<Sub>t</Sub>可达0.6,三方-四方相变温度T<Sub>rt</Sub>在90-150℃之间,居里温度T<Sub>c</Sub>大于170℃,矫顽场可达10kV/mm,可以满足超声换能器对宽带、高灵敏度、温度、电场稳定性以及性能一致性的要求。(The invention relates to ternary-system lead scandium niobate-lead magnesium niobate-lead titanate ceramic and a preparation method thereof, wherein the chemical formula of the ceramic material is xPb (Sc) 1/2 Nb 1/2 )O 3 ‑yPb(Mg 1/3 Nb 2/3 )O 3 ‑zPbTiO 3 Wherein x is more than or equal to 0.1 and less than or equal to 0.28mol, y is more than or equal to 0.32 and less than or equal to 0.57mol, z is more than or equal to 0.33 and less than or equal to 0.40mol, and x + y + z is equal to 1. The preparation method adopts the traditional two-step solid-phase reaction method to synthesize the ceramic material, and the piezoelectric constant d of the piezoelectric ceramic prepared by the method 33 Can reach 720pC/N, radial electromechanical coupling coefficient k p About 0.65, and a thickness electromechanical coupling coefficient k t Can reach 0.6, three-square phase transition temperature T rt At 90-150 deg.C and Curie temperature T c The coercive field can reach 10kV/mm at the temperature of more than 170 DEG CThe requirements of the ultrasonic transducer on broadband, high sensitivity, temperature, electric field stability and performance consistency are met.)

1. A ternary system lead scandium niobate-lead magnesium niobate-lead titanate ceramic is characterized in that the chemical formula of the ceramic material is xPb (Sc)_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃Wherein x is more than or equal to 0.1 and less than or equal to 0.28mol, y is more than or equal to 0.32 and less than or equal to 0.57mol, z is more than or equal to 0.33 and less than or equal to 0.40mol, and x + y + z is equal to 1.

2. The ternary system lead scandium niobate-lead magnesium niobate-lead titanate ceramic of claim 1, wherein the ceramic material has a chemical formula of: 0.15Pb (Sc)_1/2Nb_1/2)O₃-0.48Pb(Mg_1/3Nb_2/3)O₃-0.37PbTiO₃。

3. A method for preparing ternary-system lead scandium niobate-lead magnesium niobate-lead titanate ceramic is characterized in that the chemical formula of the ceramic material is xPb (Sc)_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃The preparation method comprises the following specific steps:

(1) to analytically pure Sc₂O₃And Nb₂O₅The powder is used as a raw material, and a precursor ScNbO is synthesized by adopting a solid-phase reaction method₄(ii) a To analytically pure MgO and Nb₂O₅The powder is used as raw material, and a precursor MgNb is synthesized by adopting a solid-phase reaction method₂O₆；

(2) To analytically pure PbO, TiO₂、ScNbO₄And MgNb₂O₆The powder is used as raw material and has the chemical formula of xPb (Sc)_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃Weighing raw materialsWherein x is more than or equal to 0.1 and less than or equal to 0.28mol, y is more than or equal to 0.32 and less than or equal to 0.57mol, z is more than or equal to 0.33 and less than or equal to 0.40mol, and x + y + z is equal to 1;

(3) putting the powder weighed in the step (2) into a ball milling tank, taking absolute ethyl alcohol as a medium, and ZrO₂The ball is a grinding ball, and a planetary ball mill is adopted for ball milling for 1-72h, so that the powder is uniformly mixed and the particle size is consistent;

(4) drying the slurry ball-milled in the step (3), pressing into a wafer of phi 40, putting the wafer into a corundum crucible, then putting the corundum crucible into a muffle furnace for presintering at the presintering temperature of 750-_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃；

(5) Grinding the pre-sintered tablets obtained in the step (4), filling the tablets into a ball milling tank, and taking absolute ethyl alcohol as a medium to obtain ZrO₂The ball is a grinding ball, and a planetary ball mill is adopted for ball milling for 1-72 h;

(6) drying the slurry ball-milled in the step (5), adding a 5% adhesive, wherein the raw material of the adhesive is polyvinyl alcohol and deionized water, adding 9g of the adhesive into 100g of powder, standing for 24h, and sieving with a sieve of 80 meshes to 200 meshes;

(7) taking powder with good fluidity between 80 and 200 meshes for tabletting and molding, wherein the molding pressure is 200 and 330MPa, and the diameter of the blank is 13 mm;

(8) placing the blank formed in the step (7) into a corundum crucible, and then placing the corundum crucible into a muffle furnace for plastic removal, wherein the plastic removal temperature is 500-750 ℃, and the plastic removal time is 1-5 h;

(9) placing the biscuit with the plastic discharged into a corundum crucible, burying the biscuit with powder with the same proportion, and placing the biscuit into a muffle furnace for sintering; the sintering temperature is 1100-_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃Piezoelectric ceramics;

(10) polishing the upper and lower surfaces of the ceramic obtained in the step (9), coating silver paste on the two surfaces, calcining at the temperature of 500-750 ℃ for 10-60min, and forming silver electrodes of about 30 micrometers on the two surfaces;

(11) and (3) placing the ceramic coated with the silver electrode obtained in the step (10) in silicone oil, polarizing for 5-60min at 130 ℃ by using an electric field of 1-5kV/mm, and testing after placing for 24 h.

Technical Field

The invention relates to the field of inorganic non-metallic functional materials, in particular to ternary-system lead scandium niobate-lead magnesium niobate-lead titanate ceramic and a preparation method thereof, which are suitable for manufacturing high-performance ultrasonic and underwater acoustic transducers.

Background

Ultrasonic detection is widely applied to a plurality of fields such as medical diagnosis, nondestructive testing, sonar and the like as a nondestructive testing technology. In the field of medical ultrasound, an ultrasound diagnostic system is a device for receiving and transmitting ultrasound signals and processing ultrasound information, and is now an indispensable device for doctors to diagnose illness. The core component of an ultrasonic diagnostic system is an ultrasonic transducer, and the performance and quality of the ultrasonic transducer directly influence the performance of the whole system. The medical ultrasonic transducer has the following characteristics that the medical ultrasonic transducer can converge wave beams, increase the detection depth and improve the sensitivity, the axial resolution and the transverse resolution of equipment. In order to obtain a clear and deep ultrasound image with a short pulse excitation, the transducer must have a wide frequency bandwidth and high sensitivity, and thus the transducer has strict design requirements. The medical ultrasonic transducer is mainly composed of a piezoelectric material, a matching layer, a back scale and the like. Wherein the piezoelectric material has the functions of transmitting and receiving ultrasonic signals, is equivalent to the heart of a transducer, and has excellent piezoelectric properties such as high piezoelectric constant d₃₃And an electromechanical coupling coefficient k_tAnd the like, the acoustoelectric conversion efficiency of the transducer is improved, and the bandwidth and the sensitivity of the transducer are further improved.

At present, lead magnesium niobate-lead titanate (PMN-PT) relaxation ferroelectric single crystals are generally adopted as the piezoelectric vibrator of the latest foreign high-end transducer. The PMN-PT monocrystal with near Morphotropic Phase Boundary (MPB) component has excellent piezoelectric and dielectric performancePiezoelectric constant d₃₃Can be more than 2000pC/N, which is 5 times of PZT piezoelectric ceramics; its electromechanical coupling coefficient k₃₃Can reach more than 90 percent, and is far more than 70 percent of PZT piezoelectric ceramics. The bandwidth of the medical ultrasonic transducer prepared by utilizing the PMN-PT single crystal is increased by more than 40%, and the resolution and the detection depth of ultrasonic imaging are effectively improved. However, due to its trigonal-tetragonal ferroelectric phase structure phase transition temperature (T)_rt) Only 60-85 ℃ and coercive field (E)_c) Also only 260V/mm, resulting in poor temperature stability and electric field stability of the transducer. On the other hand, the piezoelectric single crystal is affected by the temperature field during the generation process, and the segregation of components is serious, so that the electrical performance of the piezoelectric single crystal is inconsistent, and the consistency of the performance of the transducer is affected finally. For years, in order to solve the problems of low phase transition temperature and low coercive field of PMN-PT (positive magnetic potential transformer), a third component ion is doped in PMN-PT to adjust the tetragonal-cubic phase transition temperature T_cAnd T_rtAnd E_c. The large-size ternary piezoelectric crystals which can be grown at present mainly comprise lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT) and lead scandium niobate-lead magnesium niobate-lead titanate (PSN-PMN-PT), and T of the crystals_cAnd T_rtAnd E_cCompared with PMN-PT, the PMN-PT has great improvement, but the practical application is very limited, and the main reason is that the problem of component segregation cannot be avoided. Compared with piezoelectric single crystals, the piezoelectric ceramics basically have no composition segregation problem, have good consistency of electrical properties, and are easy to regulate and control the phase change temperature and the electrical properties by doping.

Disclosure of Invention

The invention aims to provide ternary-system lead scandium niobate-lead magnesium niobate-lead titanate ceramic and a preparation method thereof, and aims to solve the problems of low cubic phase change temperature, low coercive field, poor performance consistency and the like of piezoelectric materials used by the conventional medical ultrasonic transducer.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a ternary system lead scandium niobate-lead magnesium niobate-lead titanate ceramic has a chemical formula of xPb (Sc)_{1/ 2}Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃Wherein x is more than or equal to 0.1 and less than or equal to 0.28mol, y is more than or equal to 0.32 and less than or equal to 0.57mol, z is more than or equal to 0.33 and less than or equal to 0.40mol, and x + y + z is equal to 1.

Further, the chemical formula of the ceramic material is as follows: 0.15Pb (Sc)_1/2Nb_1/2)O₃-0.48Pb(Mg_1/3Nb_2/3)O₃-0.37PbTiO₃。

A preparation method of ternary-system lead scandium niobate-lead magnesium niobate-lead titanate ceramic is disclosed, wherein the chemical formula of the ceramic material is xPb (Sc)_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃The preparation method comprises the following specific steps:

(1) to analytically pure Sc₂O₃And Nb₂O₅The powder is used as a raw material, and a precursor ScNbO is synthesized by adopting a solid-phase reaction method₄(ii) a To analytically pure MgO and Nb₂O₅The powder is used as raw material, and a precursor MgNb is synthesized by adopting a solid-phase reaction method₂O₆；

(2) To analytically pure PbO, TiO₂、ScNbO₄And MgNb₂O₆The powder is used as raw material and has the chemical formula of xPb (Sc)_{1/ 2}Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃Weighing raw materials, wherein x is more than or equal to 0.1 and less than or equal to 0.28mol, y is more than or equal to 0.32 and less than or equal to 0.57mol, z is more than or equal to 0.33 and less than or equal to 0.40mol, and x + y + z is equal to 1;

(3) putting the powder weighed in the step (2) into a ball milling tank, taking absolute ethyl alcohol as a medium, and ZrO₂The ball is a grinding ball, and a planetary ball mill is adopted for ball milling for 1-72h, so that the powder is uniformly mixed and the particle size is consistent;

(4) drying the slurry ball-milled in the step (3), pressing into a wafer of phi 40, putting the wafer into a corundum crucible, then putting the corundum crucible into a muffle furnace for presintering at the presintering temperature of 750-_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃；

(5) Grinding the pre-sintered tablets obtained in the step (4), filling the tablets into a ball milling tank, and taking absolute ethyl alcohol as a medium to obtain ZrO₂The balls being grinding balls, miningBall milling for 1-72h by using a planetary ball mill;

(6) drying the slurry ball-milled in the step (5), adding a 5% adhesive, wherein the raw material of the adhesive is polyvinyl alcohol and deionized water, adding 9g of the adhesive into 100g of powder, standing for 24h, and sieving with a sieve of 80 meshes to 200 meshes;

(7) taking powder with good fluidity between 80 and 200 meshes for tabletting and molding, wherein the molding pressure is 200 and 330MPa, and the diameter of the blank is 13 mm;

(8) placing the blank formed in the step (7) into a corundum crucible, and then placing the corundum crucible into a muffle furnace for plastic removal, wherein the plastic removal temperature is 500-750 ℃, and the plastic removal time is 1-5 h;

(9) placing the biscuit with the plastic discharged into a corundum crucible, burying the biscuit with powder with the same proportion, and placing the biscuit into a muffle furnace for sintering; the sintering temperature is 1100-_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃Piezoelectric ceramics;

(10) polishing the upper and lower surfaces of the ceramic obtained in the step (9), coating silver paste on the two surfaces, calcining at the temperature of 500-750 ℃ for 10-60min, and forming silver electrodes of about 30 micrometers on the two surfaces;

(11) and (3) placing the ceramic coated with the silver electrode obtained in the step (10) in silicone oil, polarizing for 5-60min at 130 ℃ by using an electric field of 1-5kV/mm, and testing after placing for 24 h.

Compared with the prior art, the invention has the following beneficial effects:

the invention develops ternary-system lead scandium niobate-lead magnesium niobate-lead titanate (PSN-PMN-PT) ceramics, and the piezoelectric constant d of the ceramics₃₃Can reach 720pC/N, radial electromechanical coupling coefficient k_pAbout 0.65, and a thickness electromechanical coupling coefficient k_tCan reach 0.6, three-square phase transition temperature T_rtAt 90-150 deg.C and Curie temperature T_cThe coercive field can reach 10kV/mm when the temperature is higher than 170 ℃, and the requirements of the ultrasonic transducer on broadband, high sensitivity, temperature, electric field stability and performance consistency can be met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings of the embodiments can be obtained according to the drawings without creative efforts.

FIG. 1 shows Pb (Sc) in different compositions_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃X-ray diffraction (XRD) pattern of the ceramic.

FIG. 2 shows 0.15Pb (Sc)_1/2Nb_1/2)O₃-0.48Pb(Mg_1/3Nb_2/3)O₃-0.37PbTiO₃Dielectric thermogram of ceramic.

FIG. 3 shows 0.15Pb (Sc)_1/2Nb_1/2)O₃-0.48Pb(Mg_1/3Nb_2/3)O₃-0.37PbTiO₃Hysteresis curves of ceramics.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

The present invention will be described in further detail with reference to the accompanying drawings and examples.

The invention provides ternary-system lead scandium niobate-lead magnesium niobate-lead titanate ceramic, which has a chemical formula of xNb (Sc)_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃Wherein x is more than or equal to 0.1 and less than or equal to 0.28mol, y is more than or equal to 0.32 and less than or equal to 0.57mol, z is more than or equal to 0.33 and less than or equal to 0.40mol, and x + y + z is equal to 1.

As can be seen from fig. 1, at room temperature, the ternary ceramics of different compositions all have a pure perovskite phase, the ceramics with z 0.33 is a pure trigonal phase, the ceramics with z 0.35 and 0.36 are a trigonal and tetragonal mixed phase, and the ceramics with z 0.37 is a pure tetragonal phase.