Synthesis and characterization of yttrium iron garnet nanoparticles doped with cobalt

In this work, we have synthesized and characterized yttrium iron garnet nanoparticles doped with cobalt. The X-ray diffraction data showed a single phase, belonging to the cubic structure of Y3Fe5O12. Rietveld refinement revealed variation of the angles and interionic distances (Fe3+(a)-O2-Y3+(c) and Fe3+(d)-O2--Y3+(c) when Fe3+ ions are replaced by Co3+ ions in the tetrahedral (d) and octahedral (a) sites of YIG. In addition, the lattice parameter a, decreases from 12.3846 Å to 12.3830 Å with the increasing of cobalt concentration. The analysis by Infrared and Raman spectroscopies has shown a slight stretching at lower wave numbers as the dopant concentration increased. The magnetic measurements confirm the substitution of Fe3+ by Co3+ in the a-sites and d-sites with the reduction of the saturation magnetization from 26.63 emu/g to 24.92 emu/g, for 0.000 ≤ y ≤ 0.030. Changes in the coercive field varying the dopant concentration were related to the particle size and pinning centers existence.