Phase transition studies of sol-gel deposited barium zirconate titanate thin films

The present work was focused to investigate the phase transition behavior of sol-gel derived Ba(ZrxTi1-x)O-3 (BZT) (0 less than or equal to x less than or equal to 0.40) thin films on platinum substrates for their possible applications in piezoelectric sensors and actuators. The phase transition behavior of these films was studied using micro-Raman spectroscopy in conjunction with the temperature dependent dielectric measurements. The spectra clearly indicate that the room temperature BZT films with Zr less than or equal to 0.05 were crystallized into tetragonal structure and above 15 at.% Zr substitution BZT thin films transformed into a disordered cubic structure. This disorder behavior became more pronounced for films with Zr > 20 at.% with a plateau-type feature developing approximately 700 cm(-1) and on cooling such films to the liquid nitrogen temperature no appreciable spectral changes were noticed. The dielectric properties of such films for Zr greater than or equal to 25 at.% clearly indicated relaxor behavior. These environmentally safe (non-lead based) BZT films may have significant impact for several micro-electromechanical systems (MEMs) devices. (C) 2003 Elsevier B.V. All rights reserved.