The isotopic effect and spectroscopic studies of boron orthophosphate (BPO4)

Boron orthophosphate (BPO4) belongs to the group of SiO2-derivative structures. Its network is built up of boron and phosphorous tetrahedra, with boron and phosphorous atoms at almost the same positions as the silicon atoms in high-temperature cristobalite structure. In the present work, the interpretation of LR and Raman spectra of BPO4 was carried out based on the model of PO4 tetrahedron isolated by boron atoms. The factor group analysis enabled the separation of 12 bands due to the vibrations of PO4 tetrahedron and three bands due to pseudo-lattice baron-oxygen bond vibrations. Substitution of baron atoms with B-10 isotope caused shifts of the bands in the IR spectra, which made it possible to distinguish the bands due to boron-oxygen and phosphorus-oxygen bond vibrations. Based on the factor group analysis and isotopic effect, all bands in the IR and Raman spectra were assigned to the appropriate bond vibrations. (C) 2000 Elsevier Science B.V. All rights reserved.