Dendritic growth of yttrium aluminum garnet from an oxide melt in the system SiO2/Al2O3/Y2O3/CaO

Abstract

Glasses with the compositions x CaO·1CeF₃ (11−0.2x) Y₂O₃·(49.2−0.8x) Al₂O₃·28.8 SiO₂ (with x = 10, 20, 30 and 40) were thermally annealed at 1200 °C for 6 h. This led to the crystallization of yttrium aluminium garnet (YAG) as the only occurring phase. The crystals formed dendrites instead of monolithic bodies with large quantities of glassy phase between the dendrite arms. Large, cube shaped crystals occurred in the samples with the highest and the lowest calcium concentration (10 and 40 mol%). Interpenetrating dendrites were detected in samples with calcium concentrations of 20 and 30 mol% using electron backscatter diffraction (EBSD). The glass-ceramics show intense fluorescence due to Ce³⁺ and might be suitable for lighting technology to convert the blue light of light emitting diodes to white light.