Fabrication and magnetic properties of Fe and Co co-doped ZrO2

We investigate the effects of Fe and Co co-doping on the magnetic and electronic properties of ZrO2 ceramics prepared by a sol-gel method, and study their dependence on the annealing temperature. Dilute Fe and Co co-doping into ZrO2 exhibits ferromagnetic behavior at room temperature for annealing temperatures above 900 °C, accompanying the phase transition from tetragonal to monoclinic structure in ZrO2. The electronic structures are studied by x-ray absorption spectroscopy and M ssbauer spectroscopy, which suggest that the Fe3+ and Co2+/Co3+ mixing states are dominant in Fe and Co co-doped ZrO2.