CaTiO3 perovskite has been proposed as a ceramic waste form for immobilization of 90Sr. Nonradioactive coprecipitated xerogel powders with nominal atomic ratios of Ca:Zr:Ti = 0.75:0.25:1.00 were synthesized to mimic the fate of (Ca0.7590Sr0.25)TiO 3 solid solution after complete decay of the Sr and its intermediate product Y to stable Zr when an excess B4+ (Ti and 90Zr) cations will present. Ca:Ti = 1.00:1.00 samples were used as a reference. The powders were heated to various conditions to explore the thermodynamic stability of its oxides. The heated Ca:Zr:Ti = 0.75:0.25:1.00 samples formed a major orthorhombic Ca(Zr1-xTix)O3 perovskite phase. The Ti/(Ti + Zr) ratio of the perovskite preserves its nominal ratio at 600°C. The Zr rejects from the Ca(Zr1-xTix)O 3 with further increasing the temperature, following the formation of Ca-Ti-Zr-O secondary phases. This study indicates a tendency of the Zr to segregate from an original (Ca,Sr)TiO3 waste form when the stoichiometry is controlled by the conversion of Sr to Zr (in normal oxidation states).
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of the American Ceramic Society|
|State||Published - Aug 2013|
ASJC Scopus subject areas
- Ceramics and Composites
- Materials Chemistry