Sol-gel preparation of thick PZN-PZT film using a diol-based solution containing polyvinylpyrrolidone for piezoelectric applications

Dense and crack-free lead zinc niobate-lead zirconate titanate (PZN-PZT) films were deposited on silicon and glass substrates by spin coating using a sol containing propanediol and polyvinylpyrrolidone. Single-layer PZN-PZT films as thick as 0.80 mu m were deposited by a single spin coating with successive heat treatments at 250 degrees and 700 degrees C. After heat treatment, the films were dense, crack free, and optically transparent. In addition, the crystallographic orientation of the thick film was controllable by adjusting the heat-treatment conditions. The ferroelectric properties of the (111)-oriented film were superior to those of the (100)-oriented film. On the other hand, the piezoelectric and dielectric properties of the (100)-oriented film were better than those of the (111)-oriented film. The piezoelectric coefficients (d(33)) of the PZN-PZT films of 4.0-mu m-thickness were 192 and 110 pC/N for the (100)-and (111)-oriented films, respectively.