HYDROTHERMAL SYNTHESIS AND CRYSTAL STRUCTURES OF GALLIUM AND INDIUM PHOSPHATES. Kwang-Hwa Lii, Institute of Chemistry, Academia Sinica, Taipei, Taiwan, ROC

Aluminophosphates have been extensively studied because they are known to be useful materials for catalysis and adsorption. Gallophosphates have also been synthesized to discover new open-framework materials. The replacement of aluminum by gallium yields both novel structure types and phases that are analogous to known aluminophosphates and aluminosilicates. Compared to the large number of aluminophosphates and gallophosphates synthesized and structurally characterized there is very scant information on indium phosphates in the literature. As part of a continuing study on the structural chemistry of phosphates containing mixed octahedral-tetrahedral frameworks, the phosphates and arsenates of Group 13 elements have also been examined. The synthetic methods are two-fold, viz. the high-temperature, high-pressure hydrothermal and the flux-growth methods. Hydrothermal synthesis involves the use of aqueous solvents or mineralizers under high temperature and high pressure to dissolve and recrystallize materials that are relatively insoluble under ordinary conditions. Small gold tubes, welded at both ends containing the reactants, are used in the pressure vessels. This presentation reports the results of hydrothermal synthesis and crystal structures of several new ternary gallium and indium phosphates.