Magnetic studies of Sn0.2Cr1.8−xFexO3 compounds prepared via the hydrothermal route

Tin-iron chromium oxides (Sn0.2Cr1.8−xFexO3 with x varying from 0.3 to 1.3) have been produced by hydrothermal process in a stirred pressure reactor from pure metal chlorides. Single phase corundum structure and nanophase structure of the as-synthesized samples were confirmed by X-ray diffraction (XRD) and by transmission electron microscope (TEM). The results show that the produced powders have grain sizes in the range 25-34 nm. 57Fe Mössbauer spectra show the materials to be paramagnetic for Fe concentration x≤0.5 and in ordered magnetic state at higher concentration. The variations of grain sizes, lattice parameters, and Mössbauer parameters as a function of composition have also been investigated. The coercivity increases rapidly with size, attaining a maximum value, and then decreases with size of the particles.