Preparation and characterization of sodium bearing perovskite phases

Ceramic waste-forms constitute a major alternative to glass for immobilization of radionuclides in solid phase, with advantage of greater stability in the presence of water at moderate temperature. CaZrO 3 and SrZrO 3 with ABO 3 perovskite structure are suitable host matrices for fixation of sodium and neodymium. Three new phases with compositions Na 0.5Nd 0.5ZrO 3, Ca 0.44Na 0.28Nd 0.28ZrO 3 and Sr 0.6Na 0.2Nd 0.2ZrO 3 have been synthesized and characterized as orthorhombic phases. The crystal structure of Ca 0.44Na 0.28Nd 0.28ZrO 3 was derived from the crystallographic parameters of CaZrO 3 using X-ray powder diffraction data in the orthorhombic system by Rietveld profile method. Preliminary leaching studies carried out in a digestion bomb showed low leachability of sodium and neodymium in water at 70 °C from Ca 0.44Na 0.28Nd 0.28ZrO 3 matrix as compared to that from Sr 0.6Na 0.2Nd 0.2ZrO 3 matrix.