Microstructure and optical properties of La0.5Sr0.5Ti1−xFexO3 nanoparticles prepared by thermal decomposition

Abstract

La0.5Sr0.5Ti1–xFexO3 (x=0.005, 0.010, 0.015, and 0.020) nanoparticles were synthesized by thermal decomposition method at a calcination temperature of 900°C for 3h in air. The X-ray diffraction (XRD) results show the perovskite structure of all samples with the lattice type of cubic and the calculated crystallite size is in the range of 24–34nm. Transmission electron microscopy (TEM) bright field images show the agglomeration of nanoparticles with size of 100nm and larger. The corresponding selected-area electron diffraction (SAED) patterns show ring patterns of cubic structure which is in agreement with the XRD results. Optical absorption measurements using UV–visible spectroscopy show the absorption edge of La0.5Sr0.5TiO3 at ∼385nm and those of Fe-doped La0.5Sr0.5TiO3 nanoparticles at around 425nm. The energy gap is found to be decreased with increasing Fe concentration. The X-ray absorption spectroscopy (XAS) results of La0.5Sr0.5Ti1–xFexO3 nanoparticles indicate the oxidation states of 2+ and 3+ for Fe cations in all samples.