Role of Pb excess in the crystallization of lead zirconate titanate films derived via sol-gel processing

Abstract

Sol-gel spin coating of lead-titanate films differs from most processing routes, such as metalorganic chemical vapor deposition and pulsed laser deposition, in that crystallization cannot occur without a postdeposition annealing step. This work focuses on the annealing of sol-gel-derived PbZrTiO3 films on LaAlO3 substrates in attempts to identify the precise conditions necessary to grow films of quality similar to that obtained through other techniques. In particular, the effects of Pb excess (in precursor solutions), annealing times, and temperature were investigated through transmission electron microscopy and four-circle x-ray diffraction. The significance of this work is in the direct observation of the correlation between Pb excess and film crystallization. It is shown that the effects of Pb excess on the completeness of film crystallization become more dramatic at lower annealing temperatures, even while epitaxial quality is maintained.