Microstructure and gyromagnet properties of In-substituted YIG ferrite prepared by sol–gel method

In-substituted YIG ferrite (Y 3 Fe 5 −  x In x O 12 ) materials were prepared by citrate nitrate sol–gel method. Phase formation, microstructure, and magnetic properties were investigated, and the effects of In-substitution were discussed detailed. X-ray diffraction results showed the In-substitution did not change the phase formation of YIG ferrite, but cause the lattice constants change slowly. Scanning electron microscopy showed the materials prepared by sol-gel method had small gain size, and In 3+ enhanced grain growth. The high-substituted content had pores among grain boundaries, which was an influence factor on magnetic property. With In-substituted increase, saturation magnetization ( σ ) increased from 21.77emu/g ( x  = 0.0) to 26.94 emu/g (4π M S =1639.2 Gs) when x  = 0.4, and then decreased to 20.27 emu/g (4π M S =1230.0 Gs, x  = 0.5). Meanwhile, the coercivity ( H C ) decreased from 12.3 Oe to 12.1 Oe ( x  = 0.3) and then increased to 13.6 Oe ( x  = 0.5). For ferromagnetic resonance (FMR) linewidth (Δ H ), the narrow FMR value was Δ H =  62.82 Oe at x  = 0.4. The anisotropy linewidth Δ H a and porosity linewidth Δ H p were mainly influence factors on linewidth of materials, and the magnetism was discussed detailed. The narrow FMR linewidth and high saturation magnetization suggested the possible use of these materials in high-frequency microwave applications.