Thermal decomposition of carbonated lanthanum hydroxide

The aim of this study was to research the influence of carbonate species on the thermal decomposition of lanthanum oxide compounds. To obtain adequate carbonate fractions, pure lanthanum hydroxide and oxide, respectively, were stored in a humid carbon dioxide atmosphere. In the process, lanthanum oxide converts within 24 h to lanthanum hydroxide because of its high affinity to water. Furthermore lanthanum hydroxide has the tendency to form carbonates, due to their basic character. By means of the results of TG-FTIR and TEM, a simplified model could be derived; the thermal decomposition of carbonated lanthanum hydroxide consists of two interfering reactions: The first reaction is the thermal decomposition of lanthanum hydroxide, and the second reaction is the thermal decomposition of lanthanum hydroxide carbonate.