Preparation And Performance Optimization Of BiScO₃-PbTiO₃ High-temperature Piezoelectric Ceramics

Nowadays,the rapid development of science and technology has posed severe challenges to the working environment of piezoelectric materials,and the research of high-temperature piezoelectric materials has received a great deal of attention.The?1-x?BiScO₃-x PbTiO₃?BS-PT?binary solid solutions with excellent piezoelectric property?d33=460 pC/N?and high Curie temperature?Tc=450??near the MPB region is promising high-temperature applications.However,there are also several drawbacks of BS-PT high-temperature piezoelectric ceramics such as great attanchment to components,high cost of Sc2O3,limited mass production and so on.In order to solve these problems,Pb(Cd_1/3Nb_2/3)O₃ and Pb(Yb_1/2Nb_1/2)O₃ were chosen as the third end members to generate novel ternary systems with BS-PT.The phases structure,microstructure,dielectric properties,ferroelectric properties,piezoelectric properties,and temperature stability of the ternary systems?0.975-x?BiScO₃-x PbTiO₃-0.025Pb(Cd_1/3Nb_2/3)O₃?BS-xPT-PCN?and?0.95-x?BiScO₃-x PbTiO₃-0.05Pb(Yb_1/2Nb_1/2)O₃?BS-xPT-PYN?were systematically studied in this work.?1-x?BiScO3-x PbTiO3?x=0.60?0.66?high temperature piezoelectric ceramics near the morphotropic phase boundary?MPB?have been prepared by conventional solid-state method.The microstructural morphology,phase structure,and electrical properties of BS-xPT ceramics were investigated in detail.The coexistence of monoclinic and tetragonal phases at MPB composition enhanced the polarizability by the coupling between two dynamically equivalent energy states,resulting in the improved piezoelectric and ferroelectric properties at MPB vicinity.The BS-PT?x=0.64?ceramics possess the optimal piezoelectric and ferroelectric properties with d₃₃=450 pC/N,k_p=62%,P_r=38?C/cm²,E_c=22.7 kV/cm,the Curie temperature?T_c?of430°C,and have good temperature stability.The depolarization temperature of the sample reaches 370°C,which makes it promising candidate for high temperature piezoelectric applications.A series of BS-xPT-0.025PCN?x=0.58?0.64?piezoelectric ceramics near the morphotropic phase boundary?MPB?for high-temperature actuation application have been devised and prepared by conventional solid-state reaction method.The phase structure,morphology,dielectric,piezoelectric,and ferroelectric properties have been systematically investigated as a function of PbTiO3 content.X-ray diffraction?XRD?results revealed that with the content of PbTiO₃ increasing,the phase structure of BS-xPT-PCN ceramics gradually varied from rhombohedral phase toward tetragonal phase.Combined with the dielectric,piezoelectric,and ferroelectric performances,it was clear that MPB of BS-xPT-PCN ceramics located at the region of x=0.62.Monoclinic phase and tetragonal phase coexist near MPB,The piezoelectric constant d33,electromechanical coupling factor kp,Curie temperature Tc,remnant polarization P_r of BS-xPT-PCN ceramics with MPB composition were 508 pC/N,56%,401?and40?C/cm2,respectively,which shows that BS-x PT-PCN ceramics exhibit enhanced piezoelectric performance,and also high T_c.Moreover,the modified BS-xPT-PCN ceramics reduced the consumption of expensive Sc2O3 component in pure BS-PT systems.The dielectric peak of the ferroelectric-paramectic phase transition of BS-xPT-PCN ceramics occurs frequency dispersion.and the temperature with frequency obeys the Vogel–Fulcher relation.BS-x PT-PCN piezoelectric ceramic has good temperature stability at high temperature.The variable temperature XRD test of the sample with x=0.62 shows that the good thermal stability of the monoclinic phase and tetragonal phase makes it obtain a high depolarization temperature.The phase structure,dielectric,ferroelectric,and piezoelectric properties of?0.95-x?BiScO3-x PbTiO3-0.05Pb?Yb1/2Nb1/2?O3 ceramics were studied.It was found that an increase in x leads to a monoclinic phase appeared between the rhombohedral and tetragonal phase,which greatly enhanced the piezoelectric performance.The MPB shift slightly to x=0.60.When x=0.60,the electrical performance parameters are optimal:d₃₃=392 pC/N,k_p=53%,P_r=38?C/cm²,E_c=20.8 kV/cm,?_rmax=30266,tan?=0.0375,and Curie temperature T_c of 392?.The dielectric spectra of BS-xPT-PCN ceramics shows that the high temperature paraelectric-ferroelectric transition exhibits the relaxor behavior,and the temperature with frequency follows the Vogel–Fulcher relation.With the increase of PT content,the relaxation of the system gradually weakens.The Curie temperature of ceramics shows a trend of linear increase.Although the piezoelectric property slump a little in comparison with the BS-PT,the BS-xPT-0.05PYN systems lessen the content of Sc2O3 and decrease the production cost,showing potential for the cosmically industrial production.BS-xPT-0.05PYN piezoelectric ceramics are one of the ideal piezoelectric materials for high temperature applications.