Hot-pressing of monazite Ce0.5Pr0.5PO4 ceramic and its chemical durability

Pr-doped monazite-(Ce) ceramic with the composition of Ce0.5Pr0.5PO4 was successfully fabricated utilizing uniaxial hot-press sintering process. The effects of sintering temperature and holding time on bulk density and microstructure of ceramic were investigated, and sintering parameters were optimized. The chemical durability of ceramic was examined through MCC-1 test. The relatively optimal sintering temperature and holding time at 30 MPa were 1150 °C and 2 h, respectively. The hot-pressed ceramic has a smaller fine-grained, closer packed structure than the pressureless sintered ceramic. The element mapping images of Ce, Pr, P and O show that all the elements are almost distributed homogeneously in the monazite ceramics. Furthermore, the normalized dissolution rates of Ce and Pr decrease with increasing time and remain almost unchanged after 28 days. The 42 days normalized dissolution rates of RL(Ce) and RL(Pr) were equal to 5.7 × 10−6 and 5.3 × 10−5 g m−2 d−1, respectively.