Evaluation of stoichiometric rare-earth molybdate and tungstate compounds as laser materials

Photoluminescence spectra, photoluminescence decay curves and Raman scattering spectra have been investigated for stoichiometric rare-earth molybdate and tungstate compounds. NaNd(MoO4)(2) and NaNd(WO4)(2) show emissions due to the transition F-4(3/2) -> I-4(9/2) in Nd3+. A possibility of laser oscillation in NaNd(MoO4)(2) is pointed from comparisons of the emission intensity and the decay time constant with NaNd(WO4)(2) where laser oscillations have been reported. In NaLa(MoO4)(2) and NaLa(WO4)(2), observed emissions which are not related to La3+ are probably due to the transitions in MoO42- and WO42- molecular ions, respectively, in scheelite crystal. Raman spectra of these compounds are similar, probably related to the same crystal structure. LiEr(MoO4)(2) Shows the emissions due to transitions H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2) and F-4(9/2) -> 4I(15/2) in Er3+ respectively. which are believed to be observed for the first time. (c) 2005 Elsevier Ltd. All rights reserved.