Effect of Polyvinylpyrrolidone Molecular Weight on the Critical Thickness, Crystallization, Densification and Properties of PLZT Films

Abstract

ABSTRACTPLZT 9.5/65/35 ceramic films were prepared from the sol-gel solutions containing the stress-relaxing agent of polyvinylpyrrolidone(PVP) with the molecular weight of 40000, 360000 and 630000 (abbreviated as PVP40, PVP360 and PVP630) respectively. It is found that PVP40 can increase the critical thickness of the PLZT films to 0.22μm(compared with the critical thickness of 0.077μm in case of without PVP) and PVP360 and PVP630 can increase the critical thickness up to 0.49μm and 0.93μm individually. With the molecular weight of PVP increasing, the perovskite formation in the PLZT films was improved but the morphology of the films tended to be nano-porous. The films modified by PVP360 can be densified by optimizing the heat treatment conditions. When pyrolyzed at 600°C and then annealed at 700°C, the one-coating films with the thickness of 0.5μm were dense and exhibited a very slim hysteresis loop with the remnant polarization of 5.96×10−4μC/cm2 and coercive field of 21.51kV/cm, and a transmittance of around 90% and above in the wavelength of 450nm∼900nm.