CN103435345B - Piezoceramic material used for low and medium frequency narrow band ceramic filters - Google Patents

Abstract

The invention relates to the technical field of inorganic non-metallic materials, in particular to a piezoelectric ceramic material for a medium-low frequency narrow-band ceramic filter. The composition of the piezoelectric ceramic is: (xPbNb ₂ O ₆ -mBiCoO ₃ -y(Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ )+0.01~0.6wt.%LaMnO ₃ +0.03~0.8wt .%WO ₃ +0.01~0.6wt.%LiNbO ₃ ; where, 0.01≤x≤0.1mol, 0.01≤m≤0.1mol, 0.8≤y≤0.98mol, x+m+y=1. The dielectric constant of the prepared piezoelectric ceramics is about 1500, the mechanical quality factor is about 4200, the radial electromechanical coupling coefficient is about 0.20, the resonant frequency temperature coefficient is less than 0.01% (-55~+85°C), and the resonant frequency time The stability is less than 0.005% (aging for 200 hours), and the dielectric loss is less than 0.03%. The performance is stable and safe during use.

Description

A piezoelectric ceramic material for medium and low frequency narrowband ceramic filters

technical field

The invention relates to the technical field of inorganic non-metallic materials, in particular to a piezoelectric ceramic material for medium and low-frequency narrow-band ceramic filters, which adopts the conventional solid-phase ceramic preparation method and common chemical raw materials to prepare high-stable and high-performance piezoelectric materials. Ceramics, the piezoelectric ceramics are suitable for preparing medium and low frequency narrow-band ceramic filters. ``

technical background

Piezoelectric ceramics have excellent piezoelectric effects and are widely used in functional ceramics, such as sensors, transducers, filters, etc., and play an important role in the national economy and defense industry. Due to the lead-free piezoelectric The piezoelectric properties of ceramics are very different from those of lead zirconate titanate-based piezoelectric ceramics. At present, the application of piezoelectric ceramics is mainly lead zirconate titanate-based piezoelectric ceramics and their ternary and quaternary piezoelectric ceramics; at present, Lead zirconate titanate-based piezoelectric ceramics are mainly used to make low- and medium-frequency narrow-band ceramic filters, but their temperature stability and time stability are poor. Larger changes in bandwidth, the mechanical quality factor is not high enough, it is difficult to meet the requirements of low-frequency narrow-band ceramic filters; in order to improve the performance of piezoelectric ceramic materials, two ways are often used: one is by adding a third The second is to modify the material according to the different influences of different doping ions on the performance of the material; the present invention obtains a medium-low frequency narrow-band ceramic filter and other devices. High-temperature stable and high-performance lead niobate cobaltate bismuth zirconate titanate quaternary piezoelectric ceramics. Generally, the sintering temperature of lead zirconate titanate piezoelectric ceramics is 1260 ° C ~ 1280 ° C. The piezoelectric ceramics of the present invention The sintering temperature is 1050~1080℃, which greatly reduces energy consumption, saves costs, and can inhibit the volatilization of lead oxide. the

Contents of the invention

The purpose of the present invention is achieved like this:

A medium-low frequency narrow-band ceramic filter piezoelectric ceramic, the formula of which is: (xPbNb ₂ O ₆ -mBiCoO ₃ -y(Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ )+0.01~0.6 wt.% LaMnO ₃ +0.03~0.8 wt.% WO ₃ +0.01~0.6wt.%LiNbO ₃ ; where, 0.01≤x≤0.1 mol, 0.01≤m≤0.1 mol, 0.8≤y≤0.98 mol, x+m+y= 1. Among them, PbNb ₂ O ₆ , BiCoO ₃ , (Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ , LaMnO ₃ , and LiNbO ₃ were respectively synthesized by using conventional chemical raw materials in a solid phase method.

The amount _{of LaMnO 3 , WO 3 , LiNbO 3 added is 0.01-0.6} %, 0.03-0.8 % and 0.01~0.6%.

The dielectric constant of the piezoelectric ceramic is 1483-1512, the mechanical quality factor is 4189-4230, the radial electromechanical coupling coefficient is 0.18-0.22, and the temperature coefficient of resonance frequency is 0.004%- 0.008%, the resonant frequency time stability t _fr after aging for 200 hours is 0.0022%-0.0041%, and the dielectric loss is 0.018%-0.028%.

The preparation process of PbNb ₂ O ₆ used in the piezoelectric ceramics of the present invention comprises: the conventional chemical raw material Pb ₃ O ₄

Mix with Nb ₂ O ₅ at a molar ratio of 1/3:1, grind and mix evenly, put it in an alumina crucible and keep it warm at 900°C

After 120 minutes, PbNb ₂ O ₆ was synthesized by solid state reaction, cooled and ground through a 200-mesh sieve for later use.

The preparation process of _BiCoO3 used in piezoelectric ceramics of the present invention _comprises : conventional chemical raw materials _Bi2O3 and

Co ₂ O ₃ is prepared according to the molar ratio of 1/2:1/2, ground and mixed evenly, then put into an alumina crucible at 900°C~950°C

Keep it warm for 120 minutes, synthesize BiCoO ₃ by solid state reaction, grind it through a 200-mesh sieve after cooling, and set aside.

The preparation process _{of LaMnO3} used in piezoelectric ceramics of the present invention comprises: conventional chemical raw material _La2O3

Mix with MnO ₂ at a molar ratio of 1/2:1, grind and mix evenly, put it in an alumina crucible at 900°C~950°C

Keep it warm for 120 minutes, synthesize LaMnO ₃ by solid state reaction, grind it through a 200-mesh sieve after cooling, and set aside.

The present invention adopts the conventional solid-phase method ceramic preparation technology, that is, firstly, the batch material is ball milled and pulverized according to the formula ingredients.

After mixing and drying, add binder to granulate, then press into green sheet, and then debinding in air

and sintering, after heat preservation and natural cooling, lead niobate cobaltate bismuth zirconate titanate lead quaternary piezoelectric ceramics are obtained.

Ceramics are electroded, then polarized, aged, and tested for performance.

The formulation of piezoelectric ceramics for the above-mentioned medium and low-frequency narrow-band ceramic filters is best to adopt the following two schemes:

(xPbNb ₂ O ₆ -mBiCoO ₃ -y(Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ )+0.03~0.4wt.% LaMnO ₃ +0.04~0.6 wt.% WO ₃ +0.03~0.5wt .%LiNbO ₃ ; where, 0.02≤x≤0.08 mol, 0.02≤m≤0.08 mol, 0.84≤y≤0.96 mol, x+m+y=1;

(xPbNb ₂ O ₆ -mBiCoO ₃ -y(Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ ) +0.04~0.3 wt.% LaMnO ₃ +0.05~0.5 wt.% WO ₃ +0.04~0.4wt .%LiNbO ₃ ; where, 0.025≤x≤0.06 mol, 0.025≤m≤0.06 mol, 0.88≤y≤0.95 mol, x+m+y=1.

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

1. The dielectric constant of the prepared piezoelectric ceramics is about 1500, the mechanical quality factor (Q _m ) is about 4200, the radial electromechanical coupling coefficient (K _p ) is about 0.20, and the temperature coefficient of resonance frequency (τ _fr ) is less than 0.01% (-55~+85℃), good time stability of resonant frequency (t _fr ) less than 0.005% (aging for 200 hours), dielectric loss (tanδ) less than 0.03%; good performance stability and high safety during use .

2. The performance of the piezoelectric ceramics of this patent can be easily adjusted to meet the requirements of a series of low-frequency narrow-band ceramic filters and other devices. the

3. The ceramics can be prepared by the conventional solid-phase piezoelectric ceramics preparation process, and the raw materials used are conventional chemical raw materials, and the production cost is low. The sintering temperature of the piezoelectric ceramic of the present invention is 1050-1080° C., which greatly reduces energy consumption, saves cost, and can suppress the volatilization of lead oxide at the same time. the

Detailed ways

Now in conjunction with embodiment the present invention is described further, and table 1 provides the formula of totally 4 samples of the embodiment of the present invention. the

The main raw materials of the formulations of the 4 samples in the embodiment of the present invention are conventional chemical raw materials and pre-synthesized PbNb ₂ O ₆ , BiCoO ₃ , (Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ , LaMnO ₃ , LiNbO ₃ , according to the above formula, mix the prepared materials with distilled water or deionized water and use a planetary ball mill to mix them. Material: ball: water = 1:3: (0.6~1.0), after ball milling for 4~8 hours, bake Dried to obtain dry powder, add 5-8% of its weight to the dry powder and add a polyvinyl alcohol solution with a concentration of 10% (percentage by weight) to granulate, pass through a 40-mesh sieve after mixing, and then grind it under a pressure of 20-30Mpa. Dry pressing into a green sheet at a temperature of 750-850°C for 1-4 hours for debinding, the heating rate is 50-100°C/hour; then the sample is placed in an alumina crucible, sealed and sintered, The sintering temperature is 1050~1080°C, and the holding time is 1~2 hours, and the ceramic sheet is obtained; the ceramic sheet is ground and polished, covered with silver electrodes on both sides, and polarized in silicone oil at about 120°C, and the polarization electric field is 3000~5000 volts /mm, the polarization time is 15~20 minutes; after the polarization is completed, test the resonant frequency, test the resonant frequency after 200 hours of aging, and calculate the time stability of the resonant frequency; after the polarization is completed, after 48 hours of aging, test other properties.

The properties of the above formula samples are listed in Table 2. It can be seen from Table 2 that the dielectric constant (ε) of the prepared piezoelectric ceramics is about 1500, the mechanical quality factor (Q _m ) is about 4200, and the radial electromechanical coupling Coefficient (K _p ) is about 0.20, resonant frequency temperature coefficient (τ _fr ) is less than 0.01% (-55~+85°C), good time stability of resonant frequency (t _fr ) is less than 0.005% (aging for 200 hours), dielectric loss (tan δ) is less than 0.03%.

Table 1 The formula of totally 4 samples of the embodiment of the present invention

The performance of totally 4 formula samples of the embodiment of the present invention of table 2

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range. the

Claims (6)

1. A medium-low frequency narrow-band ceramic filter piezoelectric ceramic, the sintering temperature is 1050-1080°C, the dielectric constant of the piezoelectric ceramic is 1483-1512, the mechanical quality factor is 4189-4230, and the radial electromechanical coupling coefficient is 0.18-0.22, the temperature coefficient of resonant frequency is 0.004%-0.008% in the temperature range of -55~+85℃, the time stability t _fr of resonant frequency after aging for 200 hours is 0.0022%-0.0041%, and the dielectric loss is 0.018%- 0.028%, characterized in that: the composition of the piezoelectric ceramic is: (xPbNb ₂ O ₆ -mBiCoO ₃ -y(Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ )+0.01~0.6 wt.% LaMnO ₃ +0.03~0.8 wt.% WO ₃ +0.01~0.6wt.%LiNbO ₃ ; where, 0.01≤x≤0.1 mol, 0.01≤m≤0.1 mol, 0.8≤y≤0.98 mol, x+m+y= 1; Among them, PbNb ₂ O ₆ , BiCoO ₃ , (Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ , LaMnO ₃ , and LiNbO ₃ were synthesized by solid-phase method using conventional chemical raw materials; LaMnO ₃ , WO _{3. The} amount _of LiNbO ₃ added is 0.01 _{~ 0.6} % _{, 0.03 ~} 0.8 _{% and} 0.01~ 0.6%. 2. The piezoelectric ceramic of a medium-low frequency narrow-band ceramic filter as claimed in claim 1, characterized in that: the preparation process of the PbNb ₂ O ₆ comprises: conventional chemical raw materials Pb ₃ O ₄ and Nb ₂ O ₅ According to the molar ratio of 1/3:1, grind and mix evenly, put it into an alumina crucible and keep it warm at 900°C for 120 minutes, and synthesize PbNb ₂ O ₆ by solid state reaction, grind it through a 200-mesh sieve after cooling, and set aside. 3. The piezoelectric ceramic of a medium-low frequency narrow-band ceramic filter as claimed in claim 1, characterized in that: the preparation process of the BiCoO ₃ includes: mixing conventional chemical raw materials Bi ₂ O ₃ and Co ₂ O ₃ by 1 /2: 1/2 molar ratio ingredients, grind and mix evenly, put it into an alumina crucible and keep it warm at 900°C~950°C for 120 minutes, synthesize BiCoO ₃ by solid state reaction, grind through a 200-mesh sieve after cooling, and set aside. 4. A kind of medium and low frequency narrowband ceramic filter piezoelectric ceramics as claimed in claim 1, it is characterized in that: the preparation process of described LaMnO ₃ comprises: conventional chemical raw material La ₂ O ₃ and MnO ₂ press 1/2 : 1 molar ratio of ingredients, grind and mix evenly, put it into an alumina crucible and keep it warm at 900°C~950°C for 120 minutes, solid state reaction to synthesize LaMnO ₃ , grind through a 200-mesh sieve after cooling, and set aside. 5. The piezoelectric ceramic of a medium-low frequency narrow-band ceramic filter according to claim 1, wherein the piezoelectric ceramic is composed of: (xPbNb ₂ O ₆ -mBiCoO ₃ -y(Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ )+0.03~0.4wt.%LaMnO ₃ +0.04~0.6 wt.%WO ₃ +0.03~0.5wt.%LiNbO ₃ ; where, 0.02≤x≤0.08 mol, 0.02≤ m≤0.08 mol, 0.84≤y≤0.96 mol, x+m+y=1. 6. A kind of medium and low frequency narrow-band ceramic filter piezoelectric ceramic as claimed in claim 1, characterized in that: the composition of the piezoelectric ceramic is: (xPbNb ₂ O ₆ -mBiCoO ₃ -y (Pb _0.85 Sr _0.1 Ba _0.05 )(Zr _0.50 Ti _0.50 )O ₃ ) +0.04~0.3 wt.% LaMnO ₃ +0.05~0.5 wt.% WO ₃ +0.04~0.4wt.%LiNbO ₃ ; where, 0.025≤x≤0.06 mol, 0.025≤ m≤0.06 mol, 0.88≤y≤0.95 mol, x+m+y=1.