Sodium gadolinium tungstate NaGd(WO4)2: Growth, crystallography, and some physical properties

Abstract Pure, and Nd 3+ -doped NaGd(WO 4 ) 2 (NGW) single crystals, up to ∼85 mm long and ∼30 mm in diameter, have been grown using the Czochralski method. The Nd 3+ segregation coefficient for growth along the [1 0 0] direction was 1.3±0.025. X-ray diffraction at room temperature established the lattice constants as: a =5.2483(2) A and c =11.392(2) A, for the tetragonal scheelite-like structure (space group I4 1 /a), with two formula units in the unit cell. Inter-atomic distances and bond angles are also given. The thermal expansion coefficients were α a =11.6×10 −6  /°C and α c =23.3×10 −6  /°C, in the a and c directions, respectively. The Nd 3+ absorption spectrum at around 800 nm for E ⊥ c polarization was measured with high resolution, providing a peak absorption cross-section of 2.6×10 −20  cm 2 at 800.8 nm.