Diffusion of lanthanum into single-phase sodium zirconium phosphate matrix for nuclear waste immobilization

Sodium zirconium phosphate (NZP) is a potential material for immobilization of nuclear effluents. Up to ∼2.17 mol % (10.71 wt %) lanthanum could be loaded into NZP formulations without significant changes in the three-dimensional framework structure. The crystal chemistry of Na1+x Zr2-x La x P3O12 (x = 0.1-0.5) phases was investigated using General Structure Analysis System programming. The LaNZP phases crystallize in space group R3c with Z = 6. Powder diffraction data were subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The PO4 stretching and bending vibrations in the IR region were assigned. SEM and EDAX analysis provide evidence of La in the matrix. © 2013 Pleiades Publishing, Ltd.