Electrical resistivity of iron phosphate melts

AC electrical resistivity of iron phosphate melts, some of which contained simulated high level waste (HLW), was measured at temperatures from 950 to 1450°C. The redox ratio of iron ions in the glass was measured by Mössbauer spectroscopy. Electrical resistivity decreased slightly with time. In melts of low Na₂O content the temperature dependent electrical resistivity was irreversible during the heating and cooling cycle. This irreversibility decreased with increasing Na₂O content and was correlated to the iron redox ratio.