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 (4)G(4)(5/2) --> H-6(J) (J = 13/2, 11/2, 9/2, 7/2 and 5/2) multiplet transitions. These shifts are explained by the increased interaction of Sm3+ with its surrounding ligands under pressure. The luminescence decay curves of (4)G(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. (C) 2000 Elsevier Science B.V. All rights reserved.