Interface Optimization And Dielectric Properties Of Lead-free Barium Calcium Zirconate Titanate Piezoelectric Films

(1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3(BZT-xBCT), lead-free piezoelectricceramics have attracted researchers great attentions in recent years. In2009,researchers reported that the high piezoelectric properties were achieved at themorphotropic phase boundry (MPB) and the piezoelectric coefficient d33was620pc/N at room temperature, which can be comparable with lead-based piezoelectricceramics of PZT. However, Pb is harmful to both human and environment, PZT isfacing a global restriction. Moreover, with the rapid development of MEMS andintegrated circuit (IC), the study and demand of BZT-0.5BCT piezoelectric thin filmsare becoming hot spots.BZT-0.5BCT thin films were prepared via sol-gel method,, increasing the seedlayer Pb0.8Ca0.1Ti0.975O3(PCT)at the interfaces, the final films were pure BZCT filmsand BZCT films with PCT seed layer. XRD patterns indicated that BZCT/PCT filmshad marked (100) texture and completed crystallization compared with BZCT,Further study showed BZCT/PCT films crystallized well and dielectric performanceenhanced markedly.Pb0.8La0.1Ca0.1Ti0.975O3(PLCT) thin films of were prepared in the same methodas the seed layer. The sol concentration could be adjusted to0.05M and0.2M. Onthis basis,BZT-0.5BCT、BZT-0.5BCT/0.05M PLCT and BZT-0.5BCT/0.2M PLCTfilms, XRD patterns indicated that BZT-0.5BCT film and BZT-0.5BCT/5nm PLCTfilm annealed at500C were amorphous and there was no diffraction peak in XRDpatterns, while the BZT-0.5BCT/18nm PLCT film was fully crystallized into pureperovskite structure and showed high (100) orientation under the same annealing temperature. Implement the film crystallization at low temperatures. All theBZT-0.5BCT films could be well crystallized into perovskite structure and anyimpurity phases were not observed when the annealing temperature increased to700C, the BZT-0.5BCT film and the BZT-0.5BCT/5nm PLCT film exhibitedrandom orientation. But the BZT-0.5MPLCT exhibited high (100) orientation,achieving the purpose that seed layer control the orientation of films.