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, а=5.085 Å, b=10.482 Å‚ с=17.614 Å). 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 (τ(5D0)=537 μs), Judd-Ofelt modeling (Ω2=21.811, Ω4=7.805 and Ω6=1.203 [10−20 сm2]) and the calculation of stimulated-emission cross-sections for the 5D0→7FJ′ (J′=0…6) transitions. The LiMgMo crystals are promising for rare-earth-ion doping with application as laser materials and Raman shifters.