Structural and Magnetic Studies of Ga-doped Yttrium Iron Garnet

Abstract

Ga-doped Yttrium Iron Garnet (Y3GaxFe5−xO12, Ga:YIG) was prepared by solid state reaction method and sintering at 1 300 °C. Rietveld analysis of X-ray diffraction patterns indicated that all samples crystallized in a single cubic structure (space group Ia-3d) with decreasing lattice constant as Ga concentration increased. SEM surface micrograph images of YIG samples showed highly compacted grains with small reduction in the grain size with increasing Ga concentration. Raman spectroscopy measurements confirmed the replacement of Fe3+ ions by Ga3+ ions in the garnet structure was revealed by the observed blue shifts in Raman spectra. The saturation magnetization decreased from 28.2 to 4.98 emu g−1 with increasing x from 0.0 to 1.0 due to the preferential substitution of Ga3+ ions for Fe3+ ions at tetrahedral sites. Room temperature Mossbauer spectra for the samples revealed a reduction of the hyperfine field values for octahedral and tetrahedral sites, and the development of additional components with increasing Ga concentration. Analysis of the magnetic data and Mossbauer spectra confirmed that spin canting in the substituted garnets plays an important role in explaining the observed reduction of the saturation magnetization as x increased.