Magnetic properties dependence on Fe2+/Fe3+ and oxygen vacancies in SrTi0.95Fe0.05O3 nanocrystalline prepared by hydrothermal method

SrTi1-xFexO3 (x = 0, 0.05, 0.10, 0.15 and 0.20) nanoparticles were synthesized by hydrothermal method. SrTi0.95Fe0.05O3 samples were annealed at 500, 600 and 700 degrees C in Ar. X-ray diffraction (XRD) results indicate a perovskite structure of all as-prepared and annealed samples with the impurity phase of SrCO3 and Fe3O4 in as-prepared samples of x > 0.10. SEM micrograph of as-prepared SrTi0.95Fe0.05O3 reveals an agglomeration of nanoparticles. TEM image shows a cubic shape of as-prepared SrTi0.95Fe0.05O3 nanoparticles with an average size of 60.2 nm. X-ray absorption spectroscopy (XAS) and X-ray photoemission spectroscopy (XPS) results of all annealed SrTi0.95Fe0.05O3 samples reveal, respectively the increasing of Fe2+ cations and oxygen vacancies. Magnetic properties of as-prepared and all annealed samples were measured using the vibrating sample magnetometer (VSM). Pure SrTiO3 exhibits diamagnetic behavior, whereas as-prepared SrTi1-xFexO3 (x = 0.05 and 0.10) samples exhibit ferromagnetic behavior and those of x = 0.15 and 0.20 are paramagnetic. All annealed SrTi0.95Fe0.05O3 samples are ferromagnetic due to the F-center exchange (FCE) coupling interactions of Fe2+-V-O(2-)-Fe2+ and Fe3+-V-O(2-)-Fe3+, resulting in the maximum magnetization value of 0.02 emu/g for SrTi0.95Fe0.05O3 sample annealed at 700 degrees C. (C) 2015 Elsevier B.V. All rights reserved.