Structural Characterization And Properties Of BS-PT Piezoelectric Ceramics

With the rapid development of modern science and technology,the demand for piezoelectric materials that can work in extreme high temperature environment is becoming more and more urgent in some special fields,and a new generation of piezoelectric devices with the core high temperature piezoelectric materials as is urgently needed.Bi Sc O₃-Pb Ti O₃（BS-PT）is one of the preferred materials for high-temperature work due to its high Curie temperature and excellent electrical properties.This thesis focuses on the current BS-PT ceramic preparation process window narrow,poor temperature stability,high voltage and high Curie temperature are both difficult and other shortcomings to carry out research.Basing on the ability of Pb O can stabilize the ceramic phase structure,this study selects 0.36BS-0.64PT with the quasi-homotype phase boundary（MPB）component to investigate the influence of Pb O doping and preparation process on the ceramic structure and properties,and explore the best process conditions;based on defects Engineering and lattice distortion control phase boundary theory,explore the influence of phase structure composition on the microstructure and properties of 0.39BS-0.61PT ceramics with low lead content,and build the relationship between composition-phase boundary–structure–performance.The main results are as follows:（1）The two-component piezoelectric ceramics 0.36BS-0.64PT and 1wt%Pb-0.36BS-0.64PT were successfully prepared by solid-phase method;the introduction of 1wt%Pb O was beneficial to stabilize the phase of 0.36BS-0.64PT ceramics.Structure and electrical properties,broaden the ceramic sintering process window;the Curie temperature of 0.36BS-0.64PT component ceramics was basically not affected by 1wt%Pb O and the preparation process,all ceramics exhibited a high Curie temperature T_c=450°C;1wt%Pb-0.36BS-0.64PT ceramic has excellent piezoelectric ferroelectric properties:room temperature piezoelectric constant d₃₃=365p C/N,electromechanical coupling coefficient k_p=51%,dielectric loss tanδ=0.022.（2）The 0.39BS-0.61PT and 1wt%Pb-0.39BS-0.61PT ceramics were successfully prepared by the solid phase method;the structure distortion of the 0.39BS-0.61PT ceramic was hindered by the introduction of 1wt%Pb O,which is not conducive to the control of the ceramic phase structure and the improvement of piezoelectric performance;lattice distortion induces the phase structure of 0.39BS-0.61PT ceramics from a single trigonal to a trigonal tetragonal coexistence,successfully constructing a quasi-homotype phase boundary（MPB）;Comparing with 1wt%Pb-0.39BS-0.61P,0.39BS-0.61PT ceramics have more excellent piezoelectric ferroelectric properties:room temperature piezoelectric constant d₃₃=417p C/N,electromechanical properties k_p=53%,dielectric loss tanδ=0.02,Curie temperature T_c=415°C.From room temperature to300°C,ceramics exhibited excellent piezoelectric stability.（3）0.36Bi(Sc_1-xZr_x)O₃-0.64PbTiO₃ and 0.39Bi(Sc_1-xZr_x)O₃-0.61Pb Ti O₃（x=0.005,0.01,0.015mol）ceramics were successfully prepared by solid phase method.With the increase of Zr O₂content,the phase structure ratio of 0.36BS-0.64PT ceramics changed.When x=0.01mol,the room temperature piezoelectric constant d₃₃=415p C/N and mechanical coupling coefficient k_p=54%were obtained.At the same time,with the addition of Zr O₂,the phase structure of 0.39BS-0.61PT ceramics changed from R to the MPB phase boundary with the increase of Zr content,and the electrical performance of ceramics was significantly improved.The Curie temperature was moved to high temperature with the increase of doping content,which solves the problem that high Curie high voltage cannot be combined with high voltage,and the samples showed excellent temperature stability.When the sintering temperature is 1150°C,x=0.01mol,it has excellent electrical properties with room temperature piezoelectric constant d₃₃=436p C/N,dielectric constantε_r=1632,electromechanical coupling coefficient k_p=53%,tanδ=0.025,and Curie temperature Tc=427°C.