Photoluminescence in wide band gap corundum Mg4Ta2O9 single crystals
Li Liang, Zheng Yu-Lu, Hu Yu-Xin, Li Fang-Fei, Zhou Qiang †, Cui Tian
       

Polarized Raman spectrum in (a) Y(ZZ)-Y and (b) Z(XY)-Z geometry, with inserts showing view direction along b and c axes of Mg4Ta2O9 single crystal, respectively.