研究期間:10308~10407;Uranyl silicates are the most abundant group of uranium(VI) minerals and their structural chemistry has been extensively studied because an understanding of their structures may be a key to understanding the long-term performance of a geological repository for nuclear waste. We propose to synthesize new silicates and germanates of uranium, particularly those with unusual oxidation states and mixed-valence compounds. The synthesis of uranium silicophosphates and germanophosphates will also be performed to increase the diversity of the framework structures. The synthetic method is mainly high-temperature, high-pressure hydrothermal reactions in gold ampoules contained in a high-pressure reaction vessel at 500-600 ºC and 1000-2000 bar. Their crystal structures, photoluminescence properties, XPS and XANES spectroscopy will be studied.