Microstructure Development in Yttrium Iron Garnet

Sintering and grain-growth rates were determined for yttrium iron garnet as a function of the yttrium/iron ratio. Rates decreased with an increase in this ratio; this behavior is interpreted as a result of the oxygen content variation through the garnet field. For constant sintering time, density and grain size, as well as microstructure-dependent properties, varied through the garnet field. Remanent magnetization and coercive force in particular depended on composition and sintering temperature. The rf field for nonlinear spin-wave excitation, hcrit, measured for dense samples with grain sizes from ∼4 to 30 μm, varied by a factor of four.