Mössbauer Spectroscopic Study on xFe2O3 · (40-x)Na2O · 60P2O5 (x=5,20,30) Glasses at low temperature

Abstract

It is well known that Fe3+ ions in alkali iron phosphate glasses are in the octahedral site and play a role as the NWM(network modifier) from the isomer shift (I.S.) and the quadrupole splitting (Q.S.) at room temperature. Recently, Day et al. reported that the addition of A12O3 or Fe2O3 to a sodium phosphate glass yields the glass with considerably good chemical durability and suggested that Al3+ and Fe3+ ions constitute octahedra to be combined with PO4-chain or tetrahedra to be substituted for P5+ ions in phosphate glasses. On the other hand, using the criterion for the Debye temperature of Fe3+ ions in glasses proposed by Nishida, we can examine whether they are present in the NWM or in the NWF (network former). In this paper, Mossbauer spectroscopic study of [xFe2O3 · (40-x)Na2O· 60P2O5 (x=5,20,30)] was performed in the range of 6K to 300K. It was confirmed that both ions are in the octahedral site from I.S. and Q.S. values of Fe3+ ions. Their Debye temperature were determined to be about 350K at x=5,20,30. It was concluded that although Fe3+ ions in the sodium iron phosphate glass are present in the NWM, they are strongly combined with oxygen and act as NWF.