CN102649643B - Niobium lutetium lead plumbate-lead lanthanum zirconate titanate (PLZT) electrooptical ceramics material - Google Patents

Abstract

The invention relates to a lead niobate lutetate-lead zirconate titanate piezoelectric ceramic material. Its properties were characterized by powder diffraction, scanning electron microscopy, dielectric, piezoelectric and ferroelectric measurements, and the quasi-isomorphic phase boundary region of the ternary system was determined. And the composition 43Pb(Lu _1/2 Nb _1/2 )O ₃ -10PbZrO ₃ -47PbTiO ₃ with the best properties located in the quasi-isomorphic phase boundary region was obtained. Its piezoelectric coefficient is up to d ₃₃ =367pC/N, T _c =360°C, electromechanical coupling performance k _p =68%, coercive field E _c =17kv/cm, remanent polarization P _r =34.45μC/cm ² . It can not only meet the performance requirements of high-tech applications such as high-power sensors and high-strain drivers for piezoelectric materials, but also meet the temperature requirements of high-tech applications such as high-power sensors and high-strain drivers for piezoelectric materials.

Description

Lead niobate lutetate-lead zirconate titanate piezoelectric ceramic material

technical field

The invention relates to a novel piezoelectric ceramic composition and a preparation method of the piezoelectric ceramic composition. The chemical formula of the piezoelectric ceramic composition is (1-xy)Pb(Lu _1/2 Nb _1/2 )O ₃ -xPbZrO ₃ -yPbTiO ₃ , which is abbreviated as PLuN-PZ-PT. The material is a piezoelectric composite material with a quasi-isomorphic phase boundary structure and a Curie temperature comparable to that of PZT ceramics. It belongs to the field of functional ceramics. The piezoelectric ceramic composition is suitable for piezoelectric ceramic components such as piezoelectric ceramic filters, piezoelectric ceramic oscillators, piezoelectric ceramic oscillators and the like.

Background technique

Ferroelectric/piezoelectric materials are widely used in various functional devices, such as sensors, transducers, sonar, drivers, filters, micro-speakers, etc., due to their excellent electromechanical conversion performance and fast response speed. It plays an irreplaceable and important role in national defense and security. During World War II, scientists in the United States, Japan, and the former Soviet Union discovered BaTiO ₃ piezoelectric materials almost simultaneously. In the 1950s, B.Jaffe discovered Pb(Zr _1-x Ti _x )O ₃ , referred to as PZT. PZT ceramic material is a traditional piezoelectric material widely used in transducers and actuators, and has always occupied a dominant position in piezoelectric applications. The material exhibits a quasi-isomorphic phase boundary. PZT exhibits piezoelectric performance at the quasi-isomorphic phase boundary, and the piezoelectric coefficient of PZT piezoelectric ceramics is d ₃₃ ~ 700pC/N, and the electromechanical coupling coefficient k ₃₃ ~ 70%.

But PZT ceramics have a high sintering problem (T _s >1250°C), and PbO has a low melting point, which leads to high temperature sintering of PZT ceramics, which easily deviates from the ideal composition. In addition, the growth of PZT single crystal is particularly difficult. So far, the growth of PZT single crystal in the quasi-isotropic phase boundary region is still an insurmountable problem. In addition, the coercive field of PZT ceramics is relatively small, which is not suitable for the use of high-power sensors.

In view of the above considerations, in order to find a piezoelectric material that can be used for high power and has a high Curie temperature, we carried out a study on (1-xy)Pb(Lu _1/2 Nb _1/2 )O ₃ -xPbZrO ₃ - Study on yPbTiO ₃ (PLuN-PZ-PT) solid solution system. The preparation method, structure and electrical properties of the ternary system PLuN-PZ-PT in the quasi-isotropic phase boundary region and nearby components are studied, and a new type of high Curie temperature piezoelectric material that can be used for high-power devices is provided for the piezoelectric field. electrical material.

Contents of the invention

The purpose of the present invention is to find a new type of ferroelectric material and study its preparation process for the above-mentioned problems, so as to solve the problem that the existing high Curie temperature ferroelectric single crystal is difficult to grow and there is no piezoelectric material suitable for high-power devices. Materials, adds a new product for Piezoelectric Materials. The material can be widely used in the field of piezoelectric devices.

A novel piezoelectric ceramic composition material provided by the present invention is characterized in that the chemical composition is: (1-xy)Pb(Lu _1/2 Nb _1/2 )O ₃ -xPbZrO ₃ -yPbTiO ₃ , abbreviated as : PLuN-PZ-PT, which belongs to the typical perovskite structure. Wherein, x=0.1-0.6, y=0.4-0.5. The solid solution has a quasi-isomorphic phase boundary region. One of the contents of the present invention is to find out the position of the quasi-isotype phase boundary region of the piezoelectric ceramic composition and to study the relevant electrical properties of the piezoelectric ceramics in the quasi-isotype phase boundary region.

The preparation method of the piezoelectric composite material of the present invention, its preparation method comprises the following specific steps:

a) First prepare the precursor niobite LuNbO ₄ , preparation method: Lu ₂ O ₃ and Nb ₂ O ₅ are weighed according to the metering ratio, then add alcohol and ball mill for 24 hours, and then calcined at 1150°C for 1.5 hours to obtain niobite LuNbO ₄ .

b) Weighing LuNbO ₄ , TiO ₂ , ZrO ₂ , and PbO according to the stoichiometric ratio of the required components, wherein an excess of 3% of PbO compensates for its volatilization. It was then ball milled in alcohol and zirconia media for 24 hours.

c) The above slurry is dried (120° C.) and calcined at 800° C. for 6 hours to obtain a precursor powder.

d) The above-mentioned calcined powder was ground in a mortar for 1.5 hours, added 5% PVA to granulate, pressed into tablets, and then heated to 500°C at 1.5°C/min, kept for 2 hours, and debinding.

e) The sheet after debinding was placed in an Al ₂ O ₃ crucible, added into a PbTiO ₃ atmosphere material, heated up to 1170°C at a rate of 6-10°C/min, and held for 2.5 hours to obtain the desired sample material.

Description of drawings

Figure 1 is the X-ray powder diffraction pattern of the (1-x-y)PLuN-xPZ-yPT piezoelectric ceramic material prepared in Example 1 at room temperature. The powder diffractometer model: Rigaku MiniFlex∏.

FIG. 2 is a transmission electron micrograph of the piezoelectric ceramic solid solution prepared in Example 1. FIG. Transmission electron microscope model: JSM6700.

3 is a dielectric thermogram after polarization of the (1-x-y)PLuN-xPZ-yPT piezoelectric material prepared in Example 1. Dielectric analyzer model: Germany NovolcontrolAlpha-A.

FIG. 4 is the hysteresis loops of the (1-x-y)PLuN-xPZ-yPT piezoelectric material prepared in Example 1 under different electric fields. The model of the ferroelectric analyzer: aix-ACCTTF2000.

Fig. 5 (1-xy)Pb(Lu _1/2 Nb _1/2 )O ₃ -xPbZrO ₃ -yPbTiO ₃ ternary phase diagram and quasi-isomorphic phase boundary.

detailed description

Below in conjunction with embodiment the present invention is described in further detail and complete.

Example 1

1. Weigh Lu ₂ O ₃ and Nb ₂ O ₅ according to the stoichiometric ratio, add absolute ethanol as the medium, planetary ball mill for 12 hours, dry at 120°C, and calcinate at 1150°C for 1.5 hours to obtain the precursor LuNbO ₄ .

2. According to the general formula (1-xy)Pb(Lu _1/2 Nb _1/2 )O ₃ -xPbZrO ₃ -yPbTiO ₃ , where x=0.40 and y are respectively 0.40, 0.44, 0.45, 0.46, 0.47 , 0.48, 0.50. Weigh LuNbO ₄ , ZrO ₂ , and TiO ₂ according to the stoichiometric ratio, respectively. Let weigh more than 3% of the stoichiometric PbO to compensate for its volatilization during the sintering process; add absolute ethanol as a medium, and grind the planetary ball for 24 hours.

3. The material is dried, and the dried mixture is pressed into an Al ₂ O ₃ crucible, and synthesized at 800° C. for 6 hours.

4. Crush the synthetic material, use absolute ethanol as the medium, and planetary ball mill again for 12 hours to make it evenly mixed.

5. Discharge and dry, add binder PVA (5w%), granulate, press into a sheet with a diameter of 10mm under a pressure of 20MP, heat up to 500°C in 6 hours, keep warm for 2 hours, and discharge the plastic.

6. Perform final sintering. The sintering process is pressureless sintering at 1170°C for 2.5 hours in an oxygen atmosphere, and then cooled to room temperature with the furnace temperature.

7. The PLuN-PZ-PT ceramic material obtained after sintering was analyzed by Mini-FlexII diffractometer, and the obtained XRD pattern is shown in Figure 1. It can be seen from Figure 1 that the obtained ceramic materials are all pure perovskite structures.

8. Figure 2 is a scanning electron microscope photo of the prepared ceramic material. It can be seen from Figure 2 that the prepared ceramics all present a dense microstructure. And with the increase of PLuN content, the density and crystallinity are improved.

9. Figure 3 is the dielectric thermogram of the prepared ceramic material at a test frequency of 1 Hz to 1 MHz. It can be seen from the dielectric spectrum that with the increase of PLuN content, the Curie point decreases, and it presents a shoulder peak of the trigonal-tetragonal phase transition. In addition, the dielectric peak is broadened, and the dielectric curve appears frequency dispersion effect . This indicates that the relaxation properties of the system are enhanced with the increase of PLuN content. The dielectric characteristics indicate that the ceramic is a ferroelectric material between normal ferroelectrics and relaxor ferroelectrics.

10. Figure 4 is the ferroelectric hysteresis loop prepared in this embodiment. It can be seen from Figure 4 that compared with the PZT ceramic material, the prepared ceramic material has improved coercive field Ec and remanent polarization Pr. Suitable for high power piezoelectric devices.

Example 2

1. Weigh Lu ₂ O ₃ and Nb ₂ O ₅ according to the stoichiometric ratio, add absolute ethanol as the medium, planetary ball mill for 12 hours, dry at 120°C, and calcinate at 1150°C for 1.5 hours to obtain the precursor LuNbO ₄ .

2. According to the general formula (1-xy)Pb(Lu _1/2 Nb _1/2 )O ₃ -xPbZrO ₃ -yPbTiO ₃ , where x=0.25 and y are respectively 0.41, 0.42, 0.43, 0.45, 0.46 , 0.47, 0.48. Weigh LuNbO ₄ , ZrO ₂ , and TiO ₂ according to the stoichiometric ratio, respectively. Let weigh more than 3% of the stoichiometric PbO to compensate for its volatilization during the sintering process; add absolute ethanol as a medium, and grind the planetary ball for 24 hours.

3. The sintering temperature is set at 1100°C for 2.5 hours.

3. All the other are with embodiment 1.

Example 3

1. Weigh Lu ₂ O ₃ and Nb ₂ O ₅ according to the stoichiometric ratio, add absolute ethanol as the medium, planetary ball mill for 12 hours, dry at 120°C, and calcinate at 1150°C for 1.5 hours to obtain the precursor LuNbO ₄ .

2. According to the general formula (1-xy)Pb(Lu _1/2 Nb _1/2 )O ₃ -xPbZrO ₃ -yPbTiO ₃ , where x=0.10 and y are respectively 0.40, 0.43, 0.44, 0.45, 0.46 , 0.47, 0.48, 0.50. Weigh LuNbO ₄ , ZrO ₂ , and TiO ₂ according to the stoichiometric ratio, respectively. Let weigh PbO exceeding 3% of the stoichiometric ratio; add absolute ethanol as a medium, and planetary ball mill for 24 hours.

3. The sintering temperature is set at 1020° C. for 2.5 hours.

3. All the other are with embodiment 1.

It must be pointed out that the above examples are only used to further illustrate the present invention, and should not be interpreted as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above contents of the present invention are all Belong to the protection scope of the present invention.

Claims (3)

1. Lead niobate lutetate-lead zirconate titanate piezoelectric ceramic material, characterized in that: the main component compound of the composition is (1-xy)Pb(Lu _1/2 Nb _1/2 )O ₃ -xPbZrO ₃ - yPbTiO ₃ represents, where x=0.1-0.6, y=0.40-0.50. 2. A preparation method of the piezoelectric ceramic material according to claim 1, comprising the steps of: (1) First prepare the precursor niobite LuNbO4, weigh Lu2O3 and Nb2O5 according to the metering ratio, add alcohol to grind, and then calcinate for 1.5 hours to obtain niobite LuNbO4; (2) LuNbO is weighed according to the stoichiometric ratio of the components to be prepared , TiO 2 , ZrO 2 , PbO, wherein the excessive 3% of PbO compensates for its volatilization in the sintering process; (3) The above mixed powder is ground, the slurry is dried and calcined to obtain the precursor powder; (4) The calcined powder is ground again, granulated, tabletted, debinding, and sintered to obtain the desired piezoelectric ceramic material. 3. The piezoelectric ceramic material according to claim 1 is used in the fields of electromechanical transducers, exciters, capacitors, drivers, microwave communications, microwave dielectrics, filters, ultrasonic oscillators, energy harvesters and piezoelectric buzzers .