High-pressure fluorescence study of Sm3+ : lithium fluoroborate glass

Fluorescence spectra of Sm3+ in 49.5 H3BO3+49.5 LiF+1.0 Sm2O3 glass (L5FBS) have been measured under pressure up to 9 GPa at room temperature and also at 2 K at ambient pressure. In this pressure range, a red-shift of the order of −5 cm−1/GPa is noticed for 4G(4)5/2→6HJ (J=132, 112, 92, 72 and 52) multiplet transitions. These shifts are explained by the increased interaction of Sm3+ with its surrounding ligands under pressure. The luminescence decay curves of 4G(4)5/2 were studied up to 21 GPa and were found to be non-exponential for all pressures studied. This result can be explained either by the existence of two different Sm3+ sites with a slow and a fast fluorescence decay component or by energy transfer processes. The decay time exhibits a strong decrease with increasing pressure. At 21 GPa the decay time decreases by a factor of two with respect to the ambient pressure value. The radiative properties (lifetime, branching ratios, etc.) calculated by the Judd–Ofelt theory at ambient conditions are in close agreement with the experimental values.