Mixed alkali effect in xK2O-(30 − x) Na2O-30P2O5-40ZnO glasses

The mixed alkali effect in xK2O-(30 − x) Na2O-30P2O5-40ZnO was firstly observed. Density, DSC, DC electrical conductivity, chemical durability and IR have been carried out for xK2O-(30 − x) Na2O-30P2O5-40ZnO glasses. The DC electrical conductivity was measured in the temperature range between 100 °C and < Tg. The strength of the MAE in Tg, DC electrical conductivity, and activation energy has been determined. It is observed that the strength of MAE in DC electrical conductivity is less pronounced with the increase of temperature. The extremum of the glass transition temperature, the DC electrical conductivity, the activation energy, and the DR were observed along with the variation of K alkali ratio [K]/[K + Na] (alkali dosage is constant). The results showed that extremum was caused by the large energy mismatch for ions jumping between dissimilar alkalisʹ sites as Swensonʹs structural model suggested, generally shown as the K+ vibration pathway blocking by the Na+ due to the difference of ionsʹ diameter. IR convinced the good correlation between MAE of xK2O-(30 − x) Na2O-30P2O5-40ZnO system glasses and the origination of metaphosphate structure, secondarily pyrophosphate, and [ZnO6] octahedral.