Microstructure and optical properties of La 0.5 Sr 0.5 Ti 1− x Fe x O 3 nanoparticles prepared by thermal decomposition

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 degrees C for 3 h 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 24-34 nm. Transmission electron microscopy (TEM) bright field images show the agglomeration of nanoparticles with size of 100 nm 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 similar to 385 nm and those of Fe-doped La0.5Sr0.5TiO3 nanoparticles at around 425 nm. 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. (C) 2014 Elsevier B.V. All rights reserved.