The effect of PVP on the critical thickness and properties of PLZT ceramic films

Abstract

Increasing the critical thickness (the maximum film thickness of one coating before crack formation) is a key factor for efficiently preparing thick films by sol gel processing. In order to increase the critical thickness of lanthanum doped lead zircornate titanate (PLZT, 9/65/35) films, three types of PVP40000, PVP360000 and PVP630000 (polyvinylpyrrolidone, with the molecular weight of 40000, 360000 and 630000 individually) were used to modify the sol gel processing. Both PVP type and concentration have been found to have significant influence on the critical thickness and crystallization behavior of PLZT films. With increasing the concentration or molecular weight of PVP, the critical thickness increased. But the formation of perovskite was suppressed. PVP360000 was found to be an optimal modifier for preparing PLZT thick films. Crack-free and dense PLZT films with the thickness of 1.33 μm were prepared from PVP360000 modified sols by only three coating. The films have a transparency of about 70% in visible wavelength range and a hysteresis loop with Pr of 3.3 μC/cm2 and Ec of 40.4 kV/cm. These properties are comparable to that of the non-PVP modified films and the literature data of the films prepared by sol gel processing, MOD and sputtering.