Investigation of the influence of thermal treatment on dielectric properties in PZT-PZN ceramics

Pyrochlore-free lead zirconate titanate -lead zinc niobate ceramics have been systematically investigated in the as-sintered condition as well as after annealing. The ceramics were characterized by dielectric spectroscopy and Sawyer-Tower polarization (P-E) measurements. The powders of Pb[(Zr_1/2Ti_1/2)_1-x-(Zn_1/3Nb_2/3)_x], where x = 0.1, 0.3 and 0.5 were prepared using the columbite -(wolframite) precursor method. The general trend seems to indicate that the annealed samples become more normal-ferroelectric-like behavior as opposed to the relaxor-ferroelectric-like behavior observed in the as-sintered state. The as-sintered 0.9PZT-0.1PZN ceramic exhibited weak relaxor-ferroelectric behavior, with a relatively low dielectric constant maximum of 14,000 measured at 1 kHz. Annealing resulted in a transition to normal-ferroelectric-like behavior, a shift in the dielectric maximum temperature from 360degC to 350degC, and a dramatic increase in the dielectric constant at 1 kHz to a maximum value of 35,000 for the longer anneal. After thermal annealing at 900degC for 1 week a strong enhancement of remanent polarization (P_r) was observed.