AN INVESTIGATION OF THE EFFECT OF HEAT TREATMENT ON THE INCORPORATION OF IRON AS A NETWORK FORMER IN LITHIUM LEAD BORATE GLASSES

الملخص

Mossbauer spectroscopy was used to study the iron- containing borate glasses, polyalkaline borate glasses and also the effect of iron oxidation on the structure and electric properties lithium lead borate glasses. Investigation of the time effect of heat treatment on 25Li₂O-10PbO-65B₂0₃ based glass with addition of Fe₂O₃ up to 10mol%was performed. For 1mol% iron oxide up to 3mol% at different heat treatment (10, 20, 40, 70and 150 minutes) show quadruple doublet belongs to Fe²⁺and Fe³⁺as well as it become well resolved as the time of heat treatment increasing. In this case the iron enters the glass network as a modifier to form FeO₆ groups and Pb ions as a network former. At higher amount up to 10 mole % Mossbauer Spectra exhibit a superposition of quadruple doublet and sextet which referable to F₂O₃, and there are a transition from supper paramagnetic to ferromagnetic behavior. The iron ion exists in glass sample mainly in octahedral coordination rather than in tetrahedral coordination.