Glassy samples were prepared by quenching melts in air. Two conductivity anomalies were observed near to the glass transition temperature. One of these appeared in the isothermal conductivity as a function of annealing time. This anomaly was attributed to the oxidation of Mn2+ by O ions which penetrated into the glass matrix; thus leading to an increase in charge carrier density. The other anomaly was observed in the conductivity as a function of temperature, for various annealing times. The abnormal increase and decrease in the conductivity as a function of annealing time was suggested to result from complicated structural variations in the glass. The conductivity obeyed an Arrhenius relationship below 200C. The formation of crystalline MnBO3 caused an order-of-magnitude decrease in conductivity above 350C. The conductivity was enhanced by the redistribution of free volume between these 2 temperatures.

Investigations of Conductivity Anomalies in Li2O-4MnO-4B2O3 Glasses. S.Wang, X.Huang, C.Xu, J.Liang, L.Chen: Solid State Ionics, 2001, 140[3-4], 307-11