(Na, Zr) and (Ca, Zr) Phosphate-Molybdates and Phosphate-Tungstates: II-Radiation Test and Hydrolytic Stability

This paper introduces the results of hydrolytic stability tests and radiation resistance tests of phosphate molybdates and phosphate tungstates Na_1-xZr₂(PO₄)_3-x(XO₄)_x, X = Mo, W (0 ≤ x ≤ 0.5). The ceramics characterized by relatively high density (more than 97.5%) were produced by spark plasma sintering (SPS) of submicron powders obtained by sol-gel synthesis. The study focused on hydrolytic resistance of the ceramics in static mode at room temperature. After 28 days of testing in distilled water, the normalized leaching rate was determined. It was found that the ceramics demonstrated high hydrolytic resistance in static mode: the normalized leaching rates for Mo- and W-containing ceramics were 31·10^-6 and 3.36·10^-6 g·cm^-2·day^-1, respectively. The ceramics demonstrated high resistance to irradiation with 167 MeV Xe⁺²⁶ multiple-charged ions at fluences ranging from 1·10¹² to 6·10¹³ cm^-2. The Mo-containing Na_0.5Zr₂(PO₄)_2.5(XO₄)_0.5 ceramics were shown to have higher radiation resistance than phosphate tungstates. Radiation was shown to trigger an increase in leaching rates for W and Mo in the crystal structure of NZP ceramics.