Redox freezing temperature and Bartenev equation in a 25Na2O-15B2O3-60SiO2 glass doped with chromium and manganese

► At high temperatures, redox reactions in glass melts are in equilibrium. ► Around the glass transition temperature the reaction between chromium and manganese species is controlled by the kinetics. ► At lower temperatures, the reaction is frozen. ► These freezing temperatures depend on the cooling rate similar to Bartenev equation. ► The rate determining step in this case is the electron transfer, because a notable structural rearrangement is necessary.