Effect of the Melt Temperature on the Solidification Process of Liquid Garnets Ln3Al5O12 (Ln = Dy, Y, and Lu)

This paper reports on the solidification process of liquid garnets Ln[sub 3]Al[sub 5]O[sub 12] (Ln = Dy, Y, Lu) that was probed by differential thermal analysis. A critical temperature T[sub clg] was evidence in the liquid. Cooling from temperatures under T[sub clg] leads to the crystallization of the single garnet phase. Cooling from temperatures above T[sub clg] leads to the solidification of a mixture of perovskite LnAlO[sub 3] and aluminum oxide [alpha]-Al[sub 2]O[sub 3]. For Ln = Y, the results are in agreement with stable and metastable phase diagrams previously proposed. The YAlO[sub 3] melt was shown to display a critical temperature T[sub clp] also. Its metastable solidification from temperatures above T[sub clp] leads to the formation of the perovskite at around 1550[degrees]C.