Optical spectra of yttrium phosphate and yttrium vanadate single crystals activated with Dy3+

The optical spectra of YPO4:Dy3+ and YVO4:Dy3+ single crystals have been measured at 10 and 298 K. The luminescence spectra are dominated by a strong emission in the 575 nm region. Other bands have been observed in the 480, 665, 750 and 840 nm regions. They have been assigned to transitions from F-4(9/2) to lower lying states on the basis of the energy level scheme deduced from the 10 K absorption spectra. The Stark structure of the manifolds observed in the low temperature spectra has been reliably reproduced by a standard crystal field (CF) calculation. The room temperature absorption spectra of YVO4:Dy3+ have been analyzed using the Judd-Ofelt parameterization scheme, and the intensity parameters have been determined. Using these data the radiative lifetime for the F-4(9/2) level has been calculated. The comparison with the effective decay times deduced from time-resolved measurements allows evaluation of the efficiency of the non-radiative processes. (C) 2002 Elsevier Science B V All rights reserved.