Chemical Stability of the CsZr2(PO4)3 Phosphate with the Kosnarite Structure in Various Environments

— The CsZr 2 (PO 4 ) 3 phosphate isostructural with the mineral kosnarite has been prepared via sol–gel synthesis at 900°C, and ceramics based on this phosphate have been produced by spark plasma sintering. The relative density of the ceramics has been determined to be 75.5%. The chemical stability of the ceramic materials has been assessed at 90°C in static mode in distilled and mineral water, weakly acidic solution, and weakly alkaline solution. The minimum rates of Cs leaching were ~10 –5 to 10 –4 g/(cm 2 day). We have assessed the effect of contact medium on the mechanism of cesium leaching from the CsZr 2 (PO 4 ) 3 ceramics.