Spectral-kinetic studies of SrAlF 5 doped by trivalent rare-earth ions

Abstract

Photochemical properties of Ce 3:SrAlF 5 and Ce 3,Yb 3:SrAlF 5 single crystals together with spectroscopic and kinetic characteristics of several optically nonequivalent impurity centers and energy transfer between them are described. It is shown that co-activation by Yb 3 ions effectively suppresses color centers in Ce,Yb:SAF crystals. It was found out that in Ce,Yb:SAF crystals Yb ions exist simultaneously in 2 and 3 valent state. Three types of optically nonequivalent luminescent centers corresponding to the doublets in luminescence spectrum centered at 290, 305 and 370 nm (Ce I, Ce II, Ce III, respectively) have been observed. Analysis of luminescence spectra and decays leads to the conclusion that there is no energy transfer between either cerium centers or from Ce 3 to Yb 2 apart from the Ce III center which luminescence is slightly quenched by Yb 2. © 2012 Elsevier B.V. All rights reserved.