Papers by Keyword: Spinel Oxide

Abstract: We investigated magnetic properties of spinel oxides Zn (Cr_1-xFe_x)₂O₄ to study element substitution effects on magnetism of spin-frustrated spinel oxides ZnCr₂O₄ and ZnFe₂O₄. The present study revealed that an antiferromagnetic order of ZnCr₂O₄ (T_N ~ 13 K) is suppressed by Fe doping. Zn (Cr_1-xFe_x)₂O₄ with x = 0.1, 0.5, and 0.7 exhibits spin-glass-like behavior below ~ 10 K. On the other hand, Zn (Cr_1-xFe_x)₂O₄ with x = 0.3 exhibits the absence of magnetic order or spin-glass-like behavior down to low temperature (3 K), which is probably due to the competition of geometrical and bond frustrations.

Abstract: Co₂FeO₄ spinel oxide nano powder was synthesized by co-precipitation process. Samples were annealed at different temperatures of 500, 800 and 900^o C and the phase purity were also analyzed. As-prepared sample has two spinel phases and on annealing at 900 ^οC single phase compound formed. The crystallite size of as-prepared is found to be 11.9 nm. The crystallite size increased with increase in annealing temperature to a maximum of 17.4 nm for 900 °C. Samples were subjected to necessary characterization for finding thermal, magnetic and optical band gap.

Abstract: We report on the effect of the oxygen partial pressure ratio in the sputtering gas mixture on the electrical and magnetic properties of cubic spinel ZnCo₂O₄ thin films grown by reactive magnetron sputtering. The conduction type and carrier concentration in ZnCo₂O₄ films were found to be dependent on the oxygen partial pressure ratio. The maximum electron and hole concentration at 300 K were estimated to be as high as 1.37 × 1020 cm^-3 and 2.81 × 10²⁰ cm^-3, respectively. While an antiferromagnetic coupling was found for n-type ZnCo₂O₄, a ferromagnetic interaction was observable in p-type ZnCo₂O₄, indicating hole-induced ferromagnetic transition in spinel ZnCo₂O₄.