Effects of thermal and electrical histories on hard piezoelectrics: A comparison of internal dipolar fields and external dc bias
Rare earth modified Pb(Zr,Ti)O-3-Pb(Sb,Mn)O-3 piezoelectric ceramics have been studied for various thermal and electrical histories. In both "freshly" poled and unpoled conditions, thermal quenching was found to increase the remnant polarization (P-r) and induced strain of hard piezoelectrics, relative to that of annealed condition. A "pinched" double-loop P-E response was found in the aged unpoled condition, whereas a single P-E loop was observed after the quenching near Curie temperature. Investigations of the effect of an applied dc bias on the P-E and epsilon-E responses of hard piezoelectrics were also performed. In the unpoled and quenched condition, dc bias resulted in asymmetric P-E responses and a shift of the response along the E axis. Systematic investigations revealed that internal dipolar fields and applied positive dc biases have the same effect on domain dynamics. Large internal dipolar field is essential for high power performance. A fabrication method of quenching hard piezoelectrics near the Curie temperature before poling is proposed to enhance the induced polarization and strain levels. (c) 2007 American Institute of Physics.