Effect of the crystalline layer on the electrical behaviour of 17.7Li2O·5.2ZrO2·68.1SiO2·9.0Al2O3 glass ceramic monoliths

Abstract

Li2O–ZrO2–SiO2–Al2O3 (LZSA) glass ceramic systems are usually obtained from powder technology to obtain materials with a low thermal expansion coefficient (CTE). However, in these cases, there is a high residual porosity. An alternative to reduce the porosity involves the production of monoliths. Nevertheless, there is still a lack of crystallisation kinetics and the final properties of glass ceramic monoliths are affected such as electrical properties. This study aims to evaluate the electrical behaviour as function of the crystalline layer thickness formed on the monolith surface of a 17.7Li2O·5.2ZrO2·68.1SiO2·9.0Al2O3 (molar basis) glass ceramic LZSA composition. Monoliths thermally treated at 750, 800, and 850 °C were chosen to evaluate based on the range of the crystalline layer growth. Electrochemical impedance spectroscopy was used for the electrical characterisation of LZSA glass and the glass ceramics. The resistivity increased with increasing thermal treatment temperature due to the formation of lithium-based crystalline phases. The electrical conductivity at 25 °C of the glass ceramic thermally treated at 850 °C decreased to 1.4 × 10−13 S cm−1 from 8.7 × 10−11 S cm−1 for LZSA glass. Based on the electrical behaviour, monoliths thermally treated at 850 °C can be considered potential for dielectric industrial applications.