Chemical durability and leaching mechanism of Ce_0.5Eu_0.5PO₄ ceramics: Effects of temperature and pH values

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• 作者：Xiaofeng Zhao ; Yuancheng Teng ; ^{tyc239@163.com" class="auth_mail" title="E-mail the corresponding author} ; Lang Wu ; Yi Huang ; Jiyan Ma ; Guolong Wang
• 关键词：Monazite-(Ce) ceramics ; Hot-press sintering ; Pressureless sintering ; Temperature ; pH ; Chemical durability
• 刊名：Journal of Nuclear Materials
• 出版年：2015
• 出版时间：November 2015
• 年：2015
• 卷：466
• 期：Complete
• 页码：187-193
• 全文大小：1870 K

文摘

Ce_0.5Eu_0.5PO₄ 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 (R_n) of HPS sample was similar to that of PLS specimen in deionized water, but higher R_n 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.