Ceramic Composite Matrices Based on the LaPO4–ZrO2 System: Preparation and Properties

The original approach to the use of ceramic composites as matrices for the solidification and disposal of the actinide-rare earth fraction of high-level radioactive waste (HLW ) is considered. Ceramic composites are prepared by sintering nanosized powders of (1 – x)LaPO4–xZrO2 precalcined at 850°C using unstabilized zirconium oxide. The calcined powders are subjected to stepwise sintering in the temperature range 1000–1300°C and at 1600°C to obtain ceramic composite matrices (1 – x)LaPO4–xZrO2. Experiments on the leaching of ceramic samples sintered at a temperature of 1600°C are carried out. The rates of leaching of La3+ and Zr4+ ions from ceramic samples in distilled water are calculated; the results are compared with the previously obtained data for similar matrices in a concentrated solution of sodium chloride and sulfate. The results of the study of ceramic matrices before and after leaching by the XRD and electron microscopy methods are presented.