Spectroscopic properties of Nd3+ doped NaLa0.5Gd0.5(WO4)2 crystals

The absorption spectra of Nd3+ ions in NaLa0.5Gd0.5(WO4)2:Nd single crystals were registered in the temperature range 4.5–300 K. The crystal-field energy level scheme for the IR and visible multiplets was derived. The intensity parameters Ωt (t=2,4,6) were determined by the Judd–Ofelt method. The Nd3+ ion in the titled compound as well as in other double tungstates possesses much higher values of the oscillator strength for the hypersensitive transition 4I9/2→4G5/2 and of the intensity parameter Ω2. This fact was tentatively assigned to the lowering of the S4 symmetry of regular Nd3+ site to the C2 one.