Naotaka Sakamoto1 and Kenji Morinaga2
1Graduate Student, Kyushu University, Kasuga, Fukuoka
The glass-forming region in the binary system SnF2-P2O5 has been determined as the composition range 45-90 mol%SnF2, and all of the glasses were clear, colourless, and durable. This wide region indicated that SnF2 contributed to glass-forming as a network former (NWF). Glass transition temperature (Tg), dilatometric softening temperature (Tg), melting point (Tm) of the glasses, and viscosity of the melts were measured. The variations in these properties as a function of SnF2 content showed the maximum at 60SnF2-40P2O5 as mixed composition, and Sn4+/Sn2+ in the glasses had the maximum value at this composition judging from the chemical shifts of SnLβ 2 in the glasses. IR spectroscopic study of the glasses revealed that relative amount of P=O bond decreased and ν3 vibration of PO4 units became symmetric with increasing SnF2 content. From these results, Sn in this system was assumed to be able to bridge between PO4 units when SnF2 changed to SnOF2(Sn4+) and interacted with P=O bonds in the glass. On the basis of these results, a structure model of Sn-P-O-F glass is proposed.
SnF2-P_2O5 glass, oxyfluoride, P=O bond, network former, structure model
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