Ceramics-Silikáty 47 (2) 51-55 (2003)

VOLTAMMETRIC MEASUREMENT OF THE Pt ELECTRODE CAPACITY AND THE DETERMINATION OF THE POLYVALENT IONS DIFFUSION COEFFICIENTS IN THE GLASS MELT

J. VONDRÁK, D. ROHANOVÁ, B. KLÁPŠTĚ, J. VELICKÁ

The cyclic voltammetry has been used to investigate the kinetic behaviour of polyvalent ions in a silicate glass melt within a temperature range from 900 to 1300°C. Standard potentials of oxidation-reduction reactions of the polyvalent elements present in glass melt as refining or colouring agents (Fe and Cr) were measured. Diffusion coefficients of Fe³⁺ and Cr³⁺ ions in the melt were calculated from the shape of cyclic voltammograms. Their values were found from 10^-9 to 10^-7 cm² s^-1 respectively. Double layer capacity (480 µ F/cm²) measured in the basic glass without of polyvalent elements corresponds to the high concentration of ions in the melt.

Keywords: Electric capacity of Pt electrode, Polyvalent ions, Fe3+ and Cr3+ ions, Ion diffusion coefficients, Glass melt.