Upconversion luminescence in CaYb2−xErxGe3O10 (x = 0–2)

Abstract A new series of CaYb2−xErxGe3O10 (x = 0–2) germanates has been prepared by conventional solid state reaction and an EDTA-assisted precursor route. Strong upconversion luminescence has been detected under 980 nm diode laser excitation. Concentration dependencies study shows that the highest intensity of the lines around 408 nm (2H9/2 → 4I15/2), 524 nm (2H11/2 → 4I15/2), 548 nm (4S3/2 → 4I15/2) and 659 nm (4F9/2 → 4I15/2) is observed for the sample x = 0.2 prepared by the precursor method. The measured quantum yield for this compound is more than 3%. Possible mechanisms of energy transfer between active centers have been also proposed.