Structure and ferroelectric properties of high TcBi(Me)O3-PbTiO3 single crystal thin films

Pb(Zr,Ti)O₃ (PZT) piezoelectric ceramics with higher Curie temperature T_c are necessary for a fabrication of better micro actuators, sensors, memories and/or piezoelectric micro electromechanical systems(MEMS). New piezoelectric materials with higher T_cbeyond PZT are extensively studied. Among the new piezoelectric materials, Bi(Me)O₃-xPbTiO₃ ceramics(Me: Yb, In, Sc) are fascinated for the higher T_c materials. In this paper thin films of single crystal (1-x)BiScO₃-xPbTiO₃ (BS-xPT) were deposited by an rf-magnetron sputtering for a better understanding of ferroelectric performance of the BS-xPT. We have made a laminated composite structure comprising relaxed hetero-epitaxial single crystal thin films of high T_cBS-xPT (0.5≤x≤0.8) and SrRuO₃(SRO)/Pt/MgO hetero-structural substrates. It was confirmed their ferroelectric performances of the BS-xPT thin films were comparable to the PZT based thin films: a thin film transverse piezoelectricity e_31,f was -6.7C/m² at x=0.8 with 2P_r=~60μC/cm², 2E_c=~250 kV/cm, and ε/ε_o=~150. The BS-0.8PT thin films exhibit extraordinary high T_c with T_c=750°C. The enhanced T_c is caused by the presence of the high temperature stable interface in the laminated composite structure. The present BS-xPT thin films have a high potential for a fabrication of high temperature stable piezoelectric MEMS beyond PZT.