Indexed on: 01 Apr '02Published on: 01 Apr '02Published in: Journal of Materials Science
The structural, IR and magnetic properties of the mixed spinel Cu1 + xMnxFe2-2xO4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) system have been investigated by means of X-ray diffraction, Infrared spectroscopy, magnetization and a.c. susceptibility measurements. X-ray results confirm single-phase spinel structure for all the concentrations. The structure of CuFe2O4 is tetragonal and changes to cubic for x = 0.1 to 0.4. For x = 0.5 and 0.6 the structure become tetragonal. The lattice parameter and X-ray density are deduced and their variation with Mn4+ concentration is studied. The cation distribution derived from the X-ray diffractometry data was found to agree very well with the cation distribution obtained from magnetization measurements. X-ray intensity calculations indicate that Mn4+ occupy only octahedral [B] sites and Cu2+ and Fe3+ ions occupy both octahedral [B] and tetrahedral (A) sites. The infrared spectra obtained at room temperature in the range 200–800 cm−1 showed two absorption bands. The force constants have been obtained from IR data. The variation of the saturation magnetization per formula unit as a function of Mn4+ content x has been satisfactorily explained on the basis of Neel's collinear spin ordering model for all values of x. The Curie temperature TC determined from a.c. susceptibility data decreases with increase of Mn4+ concentration x, suggesting decrease in ferrimagnetic behaviour.