Investigation of thermal and electrical conductivity of phosphate glasses containing two transition metal oxides, lithium oxide and calcium oxide

摘要

The purpose of this investigation is to study dc conductivity in glass systems with a combination of 40P_2O_5_xV_2O_5_(35-x)MoO_3_5CaO_20Li_2O. The specimens were prepared by the conventional melt-quenching technique. The dependence of the dc conductivity on temperature and the initial concentration of samples was evaluated, and it was observed that it increases with an increase in temperature for all samples. As the vanadium oxide percentage increased, the dc conductivity also increased, and the activation energy decreased almost uniformly. Variations of activation energy and conductivity are compatible with theoretical concepts. The conductivity of these samples is mixed electronic-ionic conduction, but because of variation in the transition metal oxide concentration, electronic conductivity is more effective as a result of small polaron hopping. Also, the differential scanning calorimetry measurements of these glasses (a heating rate of 10 °C Min~(?1)) were investigated, and glass transition temperatures (T_g) were determined for each chemical composition. It was shown that the enhancement of MoO_3 concentration leads to a decrease in T_g values.