Synthesis and characterization of new borate-vanadate mixed glasses

It has been found that a series of MxOy - V2O5 - B2O3 glasses (MxOy = Li2O, Na2O, K2O and MgO) containing 10 mol% α-Fe2O3 exhibited glass-forming regions that shifted with the content of network modifier (NWM) compared to B2O3 and V2O5 glasses. The Moessbauer spectra of a series of MxOy - V2O5 - B2O3 glasses showed increased quadrupole splitting (Δ) with increasing NWM content. This suggests that the coordination numbers of the V4+ and V5+ are fixed and that the formation number of non-bridging oxygens (NBO) is considered to increase with increasing NWM content, and with increasing formation number of NBO, the Fe3+ ion site changes from VO4 to BO4 tetrahedra. Consequently, the quadrupole splitting increases with increasing NWM content. (author)