Direct Crystallization of Y₃Fe₅O₁₂ Garnet by Containerless Solidification Processing

Abstract

Yttrium-iron garnet, Y₃Fe₅O₁₂ (YIG), is formed via the peritectic reaction of YFeO₃ (YIP) and liquid phases. The direct growth of YIG from a highly undercooled melt with stoichiometric YIG composition was studied using an aero-acoustic levitator with a CO₂ laser heating system. Although a YIG droplet was successfully levitated and undercooled to 1327°C, about 250°C below its peritectic temperature (T_P), YIP was primarily solidified in the microstructure of dendritic YIP with interdendritic eutectics of YIP and FeO_X. However, when a droplet was quenched after it was undercooled below T_P, single phase of YIG without YIP and FeO_X was found. The X-ray diffraction pattern as well as microstructure indicated that YIG was solidified directly and congruently from the undercooled melt, bypassing the peritectic reaction.