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
1/2
Ti
1/2
)
(1-x)
- (Zn
1/3
Nb
2/3
x
]O
3
, 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.lPZN 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 360°C to 350°C, and a dramatic increase in the dielectric constant at 1kHz to a maximum value of 35,000 for the longer anneal. After thermal annealing at 900°C for 1 week a strong enhancement of remanent polarization (P
r
) was observed.