含Ce的水热体系中结构稳定性及变价现象

Investigations on Various Structural Types and Valence States in Cerium Containing Hydrothermal Systems

利用XRD、IR及XPS谱研究了含Ce的水热体系中产物及其经过各种后处理的样品结构稳定性及Ce离子的价态变化．结果表明，不同的原料导致Ce离子稳定于不同的价态，如直接形成包括纳米晶在内的CeO2及一新相CeOHCO3.样品CeOHCO3经2GPa的冷压处理未发生结构转变，经高温焙烧处理得到具有高结晶度的棕红色的CeO2.当初始原料为Ce2（SO4）3和Ce（NO3）3时，产物为CeO2；而当初始原料为硫酸亚铈时，产物为Ce（OH）3.讨论了Ce水热体系的晶化机制，并与同种Ce盐的热分解反应进行了对比．

By means of XRD,1R and XPS measurements, the structural types and valencestates of the products in cerium containing hydrothermal systems were investigated. Theresults show that, different starting species give different products with different stabilizedvalence states, such as direct formation of nanocrystalline CeO2 and a novel phase CeOHCO3.No structural transformation was found for sample CeOHCO3 after a cool pressure treatmentat 2 GPa. However, when CeOHCO3 was calcinated at high temperatures in air, highcrystalline CeO2 with brown color, different from that of commercial one, was obtained.