METASTABLE CRYSTALLIZATION OF ND3GA5O12 MELTS - EFFECTS OF TIME AND TEMPERATURE

The crystallization and supercooling characteristics of melts of Nd3Ga 5O12 were investigated. We focus on the occurrence of a critical soak time necessary to induce metastable crystallization (i.e. NdGaO3 + bet a-Ga2O3 rather than Nd3Ga5O12) during cooling. The variables investiga ted were the effect of: soak time, soak temperature, crucible material , and starting material (crushed Nd3Ga5O12 single crystal; calcined Nd 3Ga5O12 powder; and an unfired, stoichiometric mix of oxides). The cri tical soak time was shown to be dependent on starting material, and in creasing the soak temperature shortened the critical soak time. We sug gest that the observed critical soak time is related to a change in th e Nd3GaO12 melt, such that the crystallization of NdGaO3 is favored ov er the garnet phase.