Composition and structure dependence of the properties of lithium borophosphate glasses showing boron anomaly

This work presents a study on the structure, microstructure and properties of 50Li2O·xB2O3·(50 − x)P2O5 glasses. The structure has been studied through NMR spectroscopy and the microstructure by TEM. The properties of the glasses are discussed according to their structure and microstructural features. The introduction of boron produces new linkages between phosphate chains through P–O–B bonds, whose amount increases with boron incorporation; at the same time, a depolymerisation of the phosphate chains into Q1-type phosphate units takes place. The introduction of boron produces an increase in Tg together with a decrease in the molar volume. The room temperature electrical conductivity increases with boron content as well. However, B2O3 contents higher than 20 mol% lead to crystallisation of lithium orthophosphate which contributed to hinder ionic conduction of the glasses.