Growth, structure, Raman spectra and luminescence of orthorombic Li2Mg2(MoO4)3 crystals doped with Eu3+ and Ce3+ ions

We report on the growth and the structural, thermal, vibronic and spectroscopic properties of a complex molybdate single -crystal, Li2Mg2(MoO4)(3) (LiMgMo), doped with Eu3+ or Ce3+ ions. Few cm size crystals were grown from the flux using Li2MoO4 as a solvent. Eu:LiMgMo is orthorhombic (sp. gr. Pnma, a = 5.085 angstrom, b = 10.482 angstrom, c =17.614 angstrom). It exhibits strongly polarized Raman spectra with the most intense band at 905.2 cm -1. Eu:LiMgMo possesses positive thermal expansion. Using the Eu3+ ion as a structural probe, we argue its predominant accommodation in a single type of site A(3) with a trigonal prismatic coordination. The spectroscopy of Eu3+ is characterized by the lifetime measurement (tau(D-5(0))= 537 mu s), Judd-Ofelt modeling (Omega(2)=21.811, Omega(4) = 7.805 and Omega(6)=1.203 [10(-20) cm(2)]) and the calculation of stimulated -emission cross -sections for the D-5(0)-> F-7(J) (J'=0...6) transitions. The LiMgMo crystals are promising for rare -earth -ion doping with application as laser materials and Raman shifters.