Ce3+→Mn2+ energy transfer in the LaMgB5O10:Ce, Mn photoluminescent glasses

In glassy LaMgB5O10 : Ce, Mn the strong crystal field at the rare-earth site shifts the Ce3+ emission towards a relatively low energy range for an oxide glass, around 400 nm. It contributes to increase the Ce3+ --> Mn2+ energy transfer probability through a large overlapping between cerium emission and manganese excitation. Trivalent cerium acts both as an efficient blue emitter and as a good sensitizer for Mn2+. Hence the chromaticity and intensity of the global emission can be modulated by changing the relative concentrations of cerium and manganese activators. Taking into account the external character of the cationic orbitals involved in the excitation processes (respectively 5d and 3d), the predominant role played by exchange mechanism in the global transfer phenomenon can be predicted. Actually it is demonstrated by a detailed analysis of the spectroscopic properties using the INOKUTI-HIRAYAMA model.