Variation of the conduction band edge of (Lu,Gd)3(Ga,Al)5O12:Ce garnets studied by thermally stimulated luminescence

The shift of the conduction band (CB) edge for thirty different (Lu,Gd)3(Ga,Al)5O12:Ce compositions, with simultaneous variation in Lu/Gd and Ga/Al content was studied using thermally stimulated luminescence (TSL). Specific TSL peaks were related to impurities of Ta, Cr, Yb, Ti and Eu in Lu1Gd2Ga3Al2O12:Ce ceramics. The shift of Yb-related peak positions (in temperature and trap depth) with composition modification was investigated as well. In Gd-containing (Lu,Gd)3(Ga,Al)5O12 compositions a non-monotonous shift of the CB edge with increasing Ga content has been affirmed. The difference between thermal trap depths evaluated from our TSL experiments and optical trap depths obtained from the literature was explained by the role of lattice relaxation.