Ln
3+-stabilized Na 2 SO 4 (phase I) single crystals were grown by the Czochralski method. Differential thermal analysis revealed the influence of the ionic radius of Ln 3+ on the stabilization of Na 2 SO 4 (I). Distribution coefficients (∼0.8-1.1) were measured by the inductively coupled plasma optical emission spectroscopy method and x-ray fluorescence spectroscopy. Spectroscopic investigations yielded absorption cross sections of 0.6 × 10 −20 cm 2 (-polarized, 928.5 nm) and 1.