Synthesis and crystallization of yttrium-aluminium garnet and related compounds

• Published in: Journal of materials science 1994-01, Vol.29 (7), p.1873-1878
• Main Authors: HESS, N. J, MAUPIN, G. D, CHICK, L. A, SUNBERG, D. S, MCCREEDY, D. E, ARMSTRONG, T. R
• Format: Article
• Language: English
• Subjects: Chemistry; Elements and non-metal compounds (oxides, hydroxides, hydrides, sulfides, carbides, ...); Exact sciences and technology; Inorganic chemistry and origins of life; Preparations and properties
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/BF00351307

Amorphous oxide combustion products with compositions corresponding to Y4Al2O9, YAlO3 and Y3Al5O12 were synthesised by the glycine-nitrate process and heat treated to induce crystallisation. The crystalline structure of the resulting powders was determined by powder XRD. The phase stabilities of the crystalline phases were investigated as functions of the glycine-to-nitrate ratio, the yttrium-to-aluminium ratio and the heat treatment conditions. Heat treatment for short durations resulted in incompletely crystalline powders that consisted of a mixture of Y4Al2O9, YAlO3 and Y3Al5O12 phases, regardless of the chemical composition of the amorphous combustion product. However, heat treatment for longer durations or higher temperature generated both pure phase, monoclinic Y4Al2O9 and Y3Al5O12 with the garnet structure. Prolonged heat treatment at high temperature failed to generate pure phase orthorhombic YAlO3. Subsequent analysis revealed a sluggish, complex crystallisation process involving the formation and decomposition of several phases. 31 refs.