Magnetic ordering in Ni-Cd ferrite

A series of Ni1-xCdxFe2O4 (0.0 <= x <= 0.8) were prepared by conventional double sintering ceramic method and sintered at 1200 degrees C for 6 h. X-ray diffraction results confirmed the single-phase spinel structures of all the samples. The Curie temperature decreases linearly with increasing Cd content, which is explained due to the weakening of the A-B exchange interaction. The sample with x=0.7 shows re-entrant type of spin glass phase transitions. The magnetic moment and saturation magnetization at 20 K are found to increase with Cd content up to x=0.5 and then tends to decrease for x > 0.5. The increase in magnetic moment with cadmium is attributed to Neel's two sublattice (A- and B-sublattice) collinear models according to which the magnetic moment is the vector sum of the lattice magnetic moment. The decrease in magnetization for x > 0.5 obeys the Yafet-Kittel (Y-K) model. The increase in Y-K angles for x > 0.3 indicates the increased tendency for triangular spin arrangements on B-sites. This suggests the existence of a canted spin structure in the ferrite system with higher content of Cd. (C) 2012 Elsevier B.V. All rights reserved.