RESUMEN
The magnetic nanomaterials of CuxCo(1-x)Fe2O4 (x = 0.0, 0.5, and 1.0) were synthesized via autocombustion. The crystallite sizes of these materials were calculated from their X-ray diffraction peaks and were found to be within the range of 23-43 nm. The band near 575 cm(-1) that was observed in the Fourier transform infrared spectrum of these samples confirmed the presence of the ferrite phase. The conductivity versus temperature graph shows thermal hysteresis and exhibits the knee points at 475, 525, and 500 degrees C for copper ferrite, cobalt ferrite, and copper-cobalt ferrite, respectively. The M-H loops for these materials were traced using a vibrating sample magnetometer, and they indicated a significant increase in intrinsic coercivity due to the addition of Co2+ ions in the copper ferrite, while the remanence and saturation magnetization decreased. The ferrite materials that were used in this study exhibited good humidity sensitivity, but copper ferrite showed higher sensitivity compared to the other two materials.
RESUMEN
Pure and mixed cobalt copper ferrites are of great interest due to their widespread application in electronics and medicine. We report on the electronic structure of a nanoferrite Cu(x)Co(1-x)Fe2O4 (0.0 < or = x < or = 1.0) system studied by X-ray absorption spectroscopy. These magnetic nanoferrites (average crystallite size approximately 31-43 nm) were synthesized by an auto combustion method and are characterized by high resolution X-ray diffraction and near edge X-ray absorption fine structure measurements at the O K and Co, Cu, and Fe L-edges. The O K-edge spectra suggest that there is a strong hybridization between O 2p and 3d electrons of Co, Cu and Fe cations and Fe L3,2-edge spectra indicate that Fe ions coexist in mixed valence states (Fe3+ and Fe2+) at tetrahedral and octahedral sites of the spinel structure. Copper and cobalt ions are distributed in the divalent state in octahedral sites of the spinel structure. The origin of high saturation magnetization and coercivity in cobalt-copper ferrites are explained in light of these results.