Thermodynamics of some transition metal ions in a borosilicate glass melt

With the aid of square wave voltammetry the thermodynamics of redox equilibria were studied in a borosilicate glass melt at temperatures in the range 700-1100 degrees C. The glass melts were doped with oxides of the following transition metals: V, Cr Mn, Fe, Ni, Co, Cu, Zn, Cd and Ce. While manganese, nickel, cobalt, zinc and cadmium are reduced in a two electron step to the metallic state, iron and cerium each exhibit one reduction step in which both oxidised and reduce form are ionic. Vanadium, chromium and copper show two reduction steps. In copper doped glasses the metallic state is formed during the second step. All standard potentials measured decrease with decreasing temperature. The results are compared with those previously obtained in soda-lime-silica glass melts.