Single crystal growth in YAG ceramics of different stoichiometry

Yttrium aluminium garnet (YAG) ceramics with stoichiometric Y2O3:Al2O3 = 3:5 ratio and with excessive Y2O3 and Al2O3 content up to 5 mol.% were prepared by solid-state reaction of nanopowders. The ceramics samples in close contact with YAG single crystal seed and with SiOx intermediate layer between the contacting surfaces were held at 1800–1890 °C during 10–12 h. YAG single crystal layers grew by solid-state transformation in all ceramics investigated. The highest growth velocity 0.15 mm/h was observed in ceramics with 5 mol.% Al2O3 addition at 1890 °C and was 20 times higher than for stoichiometric ceramics at 1850 °C. The results obtained were compared with data available in the literature.

► Y3Al5O12 (YAG) ceramics were made by reactive sintering of oxides nanopowders.
► Y2O3:Al2O3 ratio changed from 3:5 (stoichiometry) up to 5 mol.% of Y2O3 or Al2O3 excess.
► Solid state crystal growth on YAG crystal seeds was observed for all ceramics compositions.
► The highest growth velocity 0,15 mm/h was observed for ceramics with 5 mol. % Al2O3 excess.
► It was obtained at 1890 °C and was 20 times higher than for 3:5 YAG ceramics at 1850 °C.