SOLID-SOLUTION (BI1-XPBX)(NI(1-X)/2TI(1+X)/2)O3 FOR NEW PIEZOELECTRIC CERAMICS

A new solid solution, (Bi1-xPbx)(Ni(1-x)/2Ti(1+x)/2)O3 (BPNT-100x)(0.3 less-than-or-equal-to x less-than-or-equal-to 0.5), is studied for their dielectric, ferroelectric, piezoelectric and mechanical properties as a new group of piezoelectric ceramics. The crystal phase of the solid solution is a perovskite structure with x greater-than-or-equal-to 0.3. The BPNT-100x system has a morphotropic phase boundary between a rhombohedral phase and a tetragonal phase at x=0.445. The Curie temperature, T(c), is over 400-degrees-C and the dielectric constant, epsilon(s), is larger than 600 at room temperature. D-E hysteresis loops are observed with large remanent polarization, P(r) greater-than-or-equal-to 30 muC/cm2, and a coercive field, E(c) less-than-or-equal-to 45 kV/cm. The electromechanical coupling factors, k33 and k31, in the longitudinal and the transverse modes are 50.3% and 23.8% at x=0.5(BPNT-50), respectively. The mechanical strength and hardness were higher than those of the conventional PZT system.