FE-57, SN-119, AND SB-121 MOSSBAUER SPECTROSCOPIC INVESTIGATIONS OF METAL ATOM INCORPORATION INTO THE OXIDE NBTIP3O12

Tin-119 and iron-57 Mössbauer spectroscopy show that the incorporation of tin and iron into the white oxide NbTiP3O12 to form black compounds of composition Sn0.5NTiP3O12 and Fe0.33NbTiP3O12 involves the accomodation of Sn2+ and Fe2+ in two types of sites in the NbTiP3O12 host lattice. The change in colour is associated which charge transfer arising from the transfer of electrons from the incorporated metal to the host lattice and the partial reduction of Nb5+ to a lower oxidation state. The compound SbTiP3O12 has been synthesised and shown by antimony-121 Mössbauer spectroscopy to contain Sb5+. The resistance of the SbTiP3O12 structure to the incorporation of tin and iron is associated with the reluctance of Sb3+ to adopt octahedral coordination. © 1990 J.C. Baltzer AG, Scientific Publishing Company.