Hydrothermal Synthesis and Characterization of Transition Metal Oxides

Abstract

Hydrothermal method has proven to be an excellent method for the synthesis of novel metal oxides and vanadates. This research pertains to the synthesis of novel lead chlorovanadate compound and of a known alkali metal trivanadate compound, KV3O8 by hydrothermal method This method has been used to synthesize many inorganic oxide compounds Hydrothermal synthesis is the use of aqueous solvents under high temperature and high pressure to dissolve and recrystallize materials. Compounds with interesting structure and physical properties are often obtained from this technique that is known as one of the low-temperature synthesis techniques for solid state compounds. There are many studies that have been done on oxides in the Pb-V-O systems There are also many vanadium oxides containing Pb, V, O elements in Pb-V-O system such as Pb1.32V8.35O16.7, PbV6O11, PbV2O6, Pb2V3O8.5, and .-PbxV2O5 bronzes (x . 0.3). In an attempt to synthesize vanadium oxides at low temperature, we were able to obtain needle shaped yellow crystals of PbVO3Cl. In the nature, there is a kombatite mineral, Pb14(VO4)2O9Cl4, with the same composition of elements. A new lead chlorovanadate, PbVO3Cl, was obtained from the reaction of NaVO3 and PbCl2 in aqueous solution of B(OH)3. The compound was prepared in an autoclave that was filled with aqueous solution of B(OH)3 and heated at 170oC for 3 days. The compound crystallizes in the space group Pnma of the orthorhombic system with formula units in a cell of dimensions a . 10.022(2)