Crystallization behavior of β′-Gd2(MoO4)3 and Gd4Mo7O27 in composition designed Gd2O3-MoO3-B2O3 glasses

The crystallization behavior of ferroelastic β′-Gd2(MoO4)3 with the molar ratio of Gd2O3/MoO3 = 1/3 and Gd4Mo7O27 with Gd2O3/MoO3 = 1/3.5 in Gd2O3-MoO3-B2O3 glasses was studied to clarify the formation mechanism of β′-Gd2(MoO4)3 and the self-powdering phenomenon induced during the crystallization more deeply. In 20Gd2O3-60MoO3-20B2O3 glass, the Gd4Mo7O27 crystalline phase was formed initially in heat-treatments at near the glass transition temperature (Tg = 516 °C) prior to the formation of the β'-Gd2(MoO4)3 crystalline phase at near the crystallization peak temperature (Tp = 583 °C). In 18.89Gd2O3-66.11MoO3-15B2O3-1Al2O3 glass (Tg = 507 °C and Tp = 572 °C) with Gd2O3/MoO3 = 1/3.5, Gd4Mo7O27 crystals were formed through the crystallization and present stably in the wide temperature range and transformed into β'-Gd2(MoO4)3 crystals at a high temperature of 900 °C, proposing new glass-ceramics consisting of Gd4Mo7O27 crystals. The self-powdering phenomenon was not observed in the crystallized glasses with Gd4Mo7O27.