Hydrothermal synthesis and field of existence of silicon-free hydrogarnets

Abstract Some new silicon-free hydrogarnets, with general form u la A 3 B 2 (OH) 12 , A and B divalent and trivalent cations, re s pectively, have been prepared by means of hydrothermal synthesis. Efforts to prepare Mg- and new Ba-hydrogarnets failed. The conditions of synthesis are described and the existence of the structure is somewhat discussed on the basis of ionic size considerations. An approximate domain of existence is proposed for these compounds.