Temperature dependence of Cu+ luminescence in barium-phosphate glasses: Effect of rare-earth ions (Sm3 +, Nd3 +) and correlation with glass structure
Glasses activated with Cu+ ions and rare-earth (RE) metals are attractive as luminescent materials for down shifting in solar cells and various photonic applications. Yet, the thermal stability of the Cu+ emission in such, in connection with the effects of RE co-dopants has remained unexplored. Hence, this work reports on the influence of temperature on Cu+ luminescence in melt-quenched barium-phosphate glasses, where the effect on such of RE co-dopants Sm3 + and Nd3 + is evaluated. Further, the basic structural features of the Cu+ and RE-containing glasses is assessed by 31P nuclear magnetic resonance (NMR) spectroscopy. The data shows that the PO4 tetrahedra belonging to terminal units (Q1) increase upon RE addition, with the most significant structural modification being produced by the large-radius Nd3 + ions. Moreover, the data shows that the activation energy for the thermal quenching of Cu+ emission decreases after RE inclusion, most dramatically for the Cu+/Nd3 + co-doped glass. An observed correlation suggests that the distinct sensitivity of the Cu+ luminescence to temperature arises from an indirect effect, namely, the changes in glass structure induced by the RE ions.