Synthesis of novel inorganic structures under unusual high pressure gas and hydrothermal conditions

The application of high pressures to synthesis in inorganic materials chemi stry significantly widens the range and type of compound that can be prepar ed. Three different high pressure systems that allow, respectively, synthes is under flowing oxygen, nitrogen and hydrothermal conditions are described together with a new result obtained on each. Under hydrothermal conditions a framework material of the composition Ca-8[AlGaSiO6](4)(OH)(8) has been prepared and structural analysis shows that this material contains uniquely linkages of the type Al-O-Ga. Under high pressure nitrogen, copper has bee n doped into the Li3N structure to levels higher than previously achieved a nd with high pressure oxygen a series of new phases of the type Ln(2)Ba(4)C u(7-x)Ni(x)O(14+delta) (247) (Ln = lanthanide, yttrium) have been synthesis ed. The valuable role of high pressures in synthetic solid state chemistry is discussed.