HOT-SPRAYED YTTRIUM IRON-GARNET

Hot spraying (evaporative decomposition of solution) of sulfates of yttrium and iron at 1000°C and above produced powders which could be sintered to 99% X-ray density with homogeneous micro-structure and controlled grain size. The powder obtained from the hot-spray reactor was well gelated. However, no detectable YIG phase was obtained in the powder. The only constituents were YFeO3 and Fe2O3. This is attributed to the fast nucleation of YFeO3 phase in the reactor. The calcination studies of these powders showed that the conversion to YIG phase began above 900°C. The calcined powder with more than 90% conversion to YIG phase was still very fine and reactive. It could be sintered to high density product with average grain size ranging from 2 μ upwards. © 1979.