Influence of strontium concentration on the structural, morphological, and electrical properties of lead zirconate titanate thin films

We report the strontium-doping effect on polycrystalline lead zirconate titanate thin films. The thin films were prepared by the polymeric precursor method and their structural, morphological, and electrical properties were studied. The Pb1-xSrxZr0.3Ti0.7 (PSZT) thin films with strontium concentration x between 0.10 and 0.30 were heated at 700 degreesC for 2 h for the crystallization. The structural phase evolution, as a function of the Sr content, was followed using micro-Raman spectroscopy, specular reflectance Fourier transform infrared spectroscopy, and X-ray diffraction (XRD). With the addition of strontium to PSZT, the broadening of the Raman peaks increases. This broadening indicates a structural change of PSZT from the tetragonal phase to a pseudocubic phase. A higher dielectric constant value, as a consequence of the higher strontium concentration, was observed. This increase may indicate the presence of a phase transition from tetragonal to pseudocubic at room temperature, which corroborates the XRD and Raman-spectra analyses, and can lead us to suppose a possible decrease of the Curie temperature. The results for the remanent polarization and the coercive field, as a function of the strontium content, showed a possible phase transformation from ferroelectric to paraelectric.