Performance Optimization Of BiScO₃-PbTiO₃ Temperature Piezoelectric Ceramics

High temperature piezoelectric transducers are desperately needed in many areas,such as aerospace,automotive,oil and gas exploration.These sensors and transducers require operating temperatures up to 300°C or higher,such as sonic logging sensors for deep sea oil and gas exploration.PZT-based piezoelectric ceramics exhibit poor stability at temperature above one-half of the T_C,due to depolarization and increased conductivity.Therefore,the actual use temperature of the PZT-based ceramics is below 200°C.There is an urgent need to develop high temperature piezoelectric materials.BS-PT ceramics have received great attention owing to their excellent properties,such as high Curie temperature and piezoelectric coefficient near the morphotropic phase boundary（MPB）(T_C=450°C,d₃₃=460 pC/N).However,BS-PT also cannot be commercialized because of high dielectric loss and degradation of performance at 250°C.Hence,it is necessary to modify the properties of the BS-PT ceramics to improve performance.In this paper,the performance of BS-PT ceramics materials,especially the performance regulation and temperature stability of materials were investigated.In order to obtain ceramic materials with low dielectric loss and high temperature stability,the BS-PT ceramics doped with PMS or PLN were prepared by traditional solid-phase synthesis method,respectively.The dielectric,ferroelectric,piezoelectric properties,temperature stability and phase structure of PMS-BS-PT and PLN-BS-PT ternary ceramics were systematically studied.In addition,we also explored the fatigue mechanism of0.01PLN-BS-PT ceramic samples under sesquipolar loading.The results show that:（1）the incorporation of PMS and PLN can improve the temperature stability of BS-PT ceramics,but the modification effect of PMS doping is better.（2）Furthermore,we studied the fatigue mechanism of the 0.01PLN-BS-PT system by applying sesquipolar loading,and the results indicate that the strain（peak-peak）value of the 0.01PLN-0.37BS-0.62PT ceramic near the MPB increased to the unipolar strain value by 2.5 times,and exhibited excellent strain memory effect.Compared with 0.01PLN-0.35BS-0.64PT,it was improved by two orders of magnitude,which makes the ceramic an excellent strain memory actuator.（3）Further research showed that in the process of sesquipolar loading,the fatigue mechanism after 10⁶ cycles was mainly domain wall pinning,and the fatigue mechanism after 10⁷ cycles could be explained by passive layer model.Our results establish a foundation for the study of fatigue mechanism under sesquipolar loading.