Mechanical and Electrochemical Properties of Lithium Aluminoborate Glasses

Overview & Synopsis

The elastic moduli and the indentation behavior of glasses from the xLi2O-5Al2O3-(95−x)B2O3 system, with x = 35, 40, and 50 were characterized. Glasses become softer and less resistant to indentation cracking as the lithium content is increased, as a result of increasing the numbers of 3-fold coordinated boron and non-bridging oxygen atoms in this composition range. In parallel, the ionic conductivity at 25 °C is increased from 3.7 10–10 to 5.5 10–8 S∙cm–1, and the activation energy, as measured in the 10 to 90 °C ranges is between 55 (50 % Li2O) and 65 (35 % Li2O) kJ∙mol–1, which shows that the ionic diffusion of lithium is easier in Li-rich compositions. Measurements of the conductivity under a compressive load aligned with the electric field revealed a mechanical-electrical coupling. The change of the activation energy with the stress is associated with an activation volume, and thus a stress sensitivity, that is increased with the lithium content.