Chemical and structural aspects of a layered acid niobium (V) phosphate

Some experimental parameters that influence in the preparation of the layered niobium phosphate were investigated, among them the molar ratio P/Nb in the reaction system and the time of reaction. Starting from that research, it was obtained, through simple stages, the acid layered niobium phosphate with the representative chemical formula NbOPO4·0.4H3PO4·1.0H2O. It was verified that the phosphoric acid in the interlayer space causes distortions to the angles of the lattice parameters. The thermal treatment of the compound up to 1000◦C promoted several chemical and physical alterations, such as phase transitions, that occurred with the preservation of the crystallographic ab plane. At the temperature of 1000◦C, was formed only a structurally well defined tetragonal system α-NbOPO4. C 2005 Springer Science + Business Media, Inc.