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)O3 (BZT) (0≤x≤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 ≤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 ≥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.