Preparation and Characterization of Ceramic/Ceramic Composite Films

Abstract

A new sol–gel-based method has been developed for fabricating dense and crack-free ceramic/ceramic composite films. The new method simply combines the modified sol–gel method together with the infiltration technique. A slurry comprising lead zirconate titanate (PZT) ceramic powder dispersed in a PZT precursor solution was first prepared and deposited on a silicon substrate by the spin-coating technique to form a composite film. The large number of pores generated in the film was then infiltrated by the subsequent deposition of a diluted PZT precursor solution. This additional infiltration process has been shown to be successful and effective in reducing porosity and the resulting PZT/PZT composite films retain good dielectric, ferroelectric and pyroelectric properties. Our results also reveal that the relative permittivity and pyroelectric coefficient of composite films increase as the PZT powder volume fraction φ increases, in accordance with similar dependences predicted by the theoretical models. For a PZT/PZT composite film with φ=0.37 and a thickness of 2.5 µm, the observed relative premittivity, dielectric loss, remanent polarization and pyroelectric coefficient are 1150, 0.037, 21 µC/cm2 and 188 µC/m2K, respectively.