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Metastable solidification process of Ln3Al5O12 (Ln ≡ Dy, Y, Lu) garnets

1993; Elsevier BV; Volume: 173; Issue: 1-2 Linguagem: Inglês

10.1016/0921-5093(93)90212-w

1873-4936

Sylvie Le Floch, J. C. Rifflet, J.P. Coutures, Monique Gervais, J.P. Coutures,

Luminescence Properties of Advanced Materials

The solidification process of liquid Ln3Al5O12 (Ln ≡ Dy, Y, Lu) garnets was investigated by differential thermal analysis (DTA) and a critical temperature Tcl was found. Cooling from temperatures below Tcl leads to the crystallization of the single garnet phase. Cooling from temperatures above Tcl leads to the solidification of a mixture of LnAlO3 perovskite and α-Al2O3. For Ln ≡ Y, the results are in agreement with previously proposed stable and metastable phase diagrams. The variation of Tcl with composition was investigated. Rapid cooling of liquid yttrium aluminium garnet in contactless conditions was performed, using an aerodynamic levitation device coupled with a CO2 laser. The results are consistent with those obtained by DTA. In addition, cooling from temperatures above around 2400 °C leads to the crystallization of a metastable form of garnet.