Chemical durability and leaching mechanism of Ce0.5Eu0.5PO4 ceramics: Effects of temperature and pH values

Ce0.5Eu0.5PO4 ceramics with high relative density were prepared by hot-press (HPS) and pressureless (PLS) sintering. The effects of temperature and pH values on the chemical durability of the ceramics were investigated. The results show that an increase of acidity significantly accelerated the corrosion of the samples. In alkaline leachates, further release elements were prevented by the newborn surface precipitation. The leach rate (Rn) of HPS sample was similar to that of PLS specimen in deionized water, but higher Rn for PLS sample was found in pH = 11 solution. Moreover, apparent activation energy of the dissolution of Eu (40 ± 4 kJ mol−1) is much higher than that of Ce (20 ± 1 kJ mol−1), leading to the higher normalized elemental leach rate of Eu. Both the Eu and Ce elements have low leach rates (10−12-10−9 m d−1) after 42 days in all the leachates studied in this work.