Voltammetric studies on the redox behaviour of Cr, Mn, Cu, Sb and As ions in Na 2 O–B 2 O 3 melts

The redox behaviour of Cr, Mn, Cu, Sb and As ions in Na2O–B2O3 melts has been studied using cyclic voltammetry, in which Cr6+/Cr3+, Mn3+/Mn2+, Cu2+/Cu+/Cu0, Sb5+/Sb3+/Sb0, and As5+/As3+/As0 redox reactions were observed. The relations between redox equilibria and the basicity of the solvent melts, i.e. an analogue of the Pourbaix diagram, are presented. The diffusion coefficients of Cr6+, Mn3+, Cu2+ and Sb5+ and the temperature dependences were evaluated.