Effect of Phase Transformation on the Densification of Layo3 Pellets

Abstract

Fabrication process of LaYO3 pellets was studied to develop a reaction-preventing material for casting metallic nuclear fuel. LaYO3 pellets were fabricated by sintering La2O3 and Y2O3 powders. Phase transformation and densification behavior of the LaYO3 were investigated at various temperatures to find optimal conditions of LaYO3 sintering process. Two different LaYO3 structures were formed depending on sintering temperature; an orthorhombic perovskite LaYO3 structure was formed at the sintering temperatures of 1633, 1703, 1743, 1763, 1773, and 1793 K, while a monoclinic LaYO3 structure was formed at a sintering temperature of 1843 K. The Bulk density of sintered LaYO3 pellets increased up to 1763 K, and decreased at the temperatures ranging from 1763 to 1843 K. This study demonstrated that the formation of the LaYO3 phases and the density of the LaYO3 sintered pellets were regulated by varying the sintering temperature. Thus, the fabrication temperature of the high-density LaYO3 sintered pellets was optimized, and the mechanism of the change in density was elucidated.

Keywords: LaYO3, Cold isostatic pressing, Densification behavior, Reaction-preventing material, Ceramic crucible