Doping Modification Of BiYbO₃-Pb（Zr,Ti）O₃ Ternary Piezoelectric Ceramics Study On Sintering Characteristics

As an important functional material that can convert mechanical energy and electrical energy,piezoelectric ceramics have been widely used in many fields such as social economy and national defense security.With the development of science and technology,piezoelectric ceramics are shifting from conventional applications to special applications in extreme environments such as high temperature.BiYbO₃-Pb(Zr_0.48Ti_0.52)O₃ is a typical ternary perovskite structure ferroelectric.It has a higher Curie temperature（Tc=391℃）than the traditional binary system PZT.It is expected to be used as a sensitive element in devices with operating temperatures above 200°C.However,the piezoelectric properties(d₃₃=238 p C/N)and temperature stability of the system materials also need to be improved to meet the application requirements of high sensitivity and high stability piezoelectric devices.In this paper,0.06BiYbO₃-0.94Pb(Zr_0.48Ti_0.52)O₃（BY-PZT）was selected as the basic formula,and BY-PZT-based piezoelectric ceramic samples（hereinafter referred to as BY-PZT ceramics or samples）were prepared by solid-state reaction method.The effects of dopant type,concentration and sintering temperature on the microstructure and electrical properties of the ceramics were studied.The high-temperature electrical properties of the ceramics were characterized by means of dielectric temperature spectrum analysis,high-temperature resonance-anti-resonance test and thermal depolarization experiment.The mechanism of improving the performance of ternary perovskite structure ceramics was revealed.The main research contents of this paper are as follows:1.The effects of different oxides（La₂O₃、Ce O₂、Cr₂O₃、Mn O₂）doping on the structure and properties of BY-PZT ceramics were studied.The samples are all single tetragonal phase,and the grains of Cr₂O₃ doped samples grow abnormally.Dielectric temperature spectrum confirmed that four kinds of oxide doping can improve the temperature stability of dielectric properties.It was found that the Cr₂O₃ doped sample had the largest high temperature impedance at the same temperature.The samples doped with La₂O₃ have both high T_C～397℃and high d₃₃～290 p C/N.Moreover,with the increase of temperature,the radial resonance frequency（f_r）and anti-resonance frequency（f_a）of the sample gradually approach.2.The effects of La₂O₃ doping（x=0～0.6 wt.%）on the structure and properties of BY-PZT-x La ceramics were studied.The results show that the dielectric loss factor（tanδ）and T_Cdecrease with the increase of x.The dielectric temperature behavior of BY-PZT-x La ceramics above T_C was studied by modified Curie-Weiss law,and it was found that there was a diffuse phase transition characteristic.The component x=0.1 has a high T_C～388℃,the highest d₃₃～320 p C/N,and a thermal depolarization temperature T_d～350℃close to its TC,showing excellent temperature stability.3.The effects of sintering temperature（1040℃～1120℃）on the structure and properties of BY-PZT-0.1La ceramics were studied.With the increase of sintering temperature,the average grain size（D_λ）of ceramics increased from 1.26μm to 1.65μm,and the relative density and dielectric constant increased first and then decreased.The sample sintered at 1100℃is the most dense(ρ_rel=97.75%),and has excellent electrical properties:ε_r=1300、k_p=53.23%、tanδ=2%.