Redox glass-forming melts

Intrinsic Redox System of Oxidic Glass-Forming Melts. 1156... 

It was essential for the application of the cell for scientific and technical purposes to confirm its correct and reversible response with respect to the intrinsic redox system, Oj/O ", of glass-forming melts. Since, however, melts are open systems with respect to dissolved gases and standard melts with defined oxygen contents are not available, the correct functioning was verified on a thermodynamic basis [S]. 

The quantity (d Th,m/dr) in the integral of Equation (26-36) is defined standard Seebeck coefficient and is a characteristic property of a glass-forming melt. It is determined by means of zirconia microelectrodes (Figure 26-14), which eliminate temperature-dependent redox potentials inherently included in the emf if platinum electrodes were applied to these measurements [12]. The cell scheme for measuring standard Seebeck coefficients according to Figure 26-14 is... 

Temperature-dependent thermodynamic standard data of an-timony(III)/antimony(V) redox equilibrium (Equation (26-28)), in an oxidic glass-forming silicate melt see also Figure 26-18. 

But today it is possible to measure this property at several institutes like TNO, Glass Service, and the Universities in Prague or St Petersburg [19]. Of course, all data should be supplied as function of temperature. The thermal conductivity is usually presented in a polynomial form to the third order as function of temperature. The error for Ais can easily be 10%. Next to it, the thermal conductivity in fact varies as function of the local redox state in the glass melt due to the shift of Iron from the 2 state to the 3 state. Fe absorbs heat and Fe almost does not. 

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