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. CaZrO3 and SrZrO3 with ABO3 perovskite structure are suitable host matrices for fixation of sodium and neodymium. Three new phases with compositions Na0.5Nd0.5ZrO3, Ca0.44Na0.28Nd0.28ZrO3 and Sr0.6Na0.2Nd0.2ZrO3 have been synthesized and characterized as orthorhombic phases. The crystal structure of Ca0.44Na0.28Nd0.28ZrO3 was derived from the crystallographic parameters of CaZrO3 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 Ca0.44Na0.28Nd0.28ZrO3 matrix as compared to that from Sr0.6Na0.2Nd0.2ZrO3 matrix.