Advanced considerations for the redox interactions of multivalent elements in glasses and melts

Although the presence of two different multivalent elements in glasses and melts has been of interest in the glass science community and the technology sector for some time, different opinions about their redox interactions have existed. Here, we examine the in situ Fe-redox potential and thermodynamics of the redox interactions of various multivalent elements that form pairs with Fe in the melt state by the potentiometry and voltammetry. For the secondary multivalent element in the Fe redox reaction, the same tendencies for the glass and melt states were observed. These findings confirm that the effect is derived from the melt state. The suggested interaction reactions at the equilibrium state based on the Fe-redox ratio are clearly demonstrated by the standard free energy. Additionally the difference of the Fe redox potential for the specific redox pairs is explained by the oxyegen equilibrium pressure. These results might be generalised to other redox pairs in other glass systems.