Crystal growth and optical properties of Ca3NbGa3Si2O14 single crystals grown under various atmosphere

We grew Ca
₃
NbGa
₃
Si
₂
O
₁₄
(CNGS) single crystals in Air, Ar+3%O
₂
and Ar atmosphere by the micro-pulling-down (μ-PD) method in order to clarify the origin of the crystal color. While the CNGS crystal grown in Air indicated orange color, the crystal grown in Ar was colorless. CNGS crystal grown in Air indicated several large absorption peaks around 360 and 500 nm in the transmittance spectrum. In contrast, the crystal grown in Ar didn't indicate these absorption peaks.