The Nd3+:LiGd(WO4)2 crystal with dimensions of 25mm × 28mm × 16mm was grown by the top-seeded solution growth method from the 60 mol% Li2W2O7 flux. LiGd(WO4)2 crystallizes in the tetragonal system with space group I41/a (C4h6) and cell parameters: a =5.1986 and c = 11.2652 Å. The hardness is about 5.0 Mohs’ scale. The specific heat is 0.40 J·g-1·K-1 at 50 oC. The thermal expansion coefficients for a- and c-axes are 1.314 × 10-5 and 2.052 × 10-5 K-1, respectively. The room-temperature polarized absorption and emission spectra and the fluorescence decay curve was measured. The parameters of oscillator strengths, the spontaneous transition probabilities, the fluorescence branching ratios, the radiative lifetimes, and the emission cross sections have been investigated based on Judd-Ofelt theory and Füchtbauer-Ladenburg method. The absorption cross-section is 5.19 × 10-20 cm2 at 805 nm for π-polarization and its line width is 15 nm; the emission cross section is 1.726 10-19 cm2 at 1060.5 nm for π-polarization. The fluorescence and radiative lifetimes are 86 and 158 μs, respectively. The fluorescence quantum efficiency is 54.43%.
Received: 28 May 2010
HUANG Xin-Yang , WANG Guo-Fu