Structure and Coordination Investigation of Iron-ion Tinting Principle in Ferreous Glass

The tinting phenomena of iron oxide contained glasses were studied from aspects of the electronic configuration, the iron ions coordination fields and the ions structure in glass. Several iron ion tinting forms at different redox or COD ( chemical oxygen detand ) conditions and their influential factors were given necessary explanations. The resalts reveal that the Fe^3+ -O-Fe^2+ structure is the real tinting reason of iron involved glasses,whereas the Si^4+ -O-Fe^3+ and Si^4+ -O-Fe^2+ formalxaions modify the glass colours. Under oxidizing melting condition, the amount of 4/6-coordinated Fe^3+ inereases and makes the glass colour yellowish. Conversely, reducing melting condition makes the 6-coordinated Fe^2+ increased and gives much blue tint to the glass. The conventional tank furnace tuelting the very strong reducing condition, which is of high COD glass batch, is not suitable. The high ratio of ferroas/ ferric in glass can be obtained with a new refining technology which contains no or little amount of refining agent.