Ionic conductivity of Li5AlO4 and Li5GaO4 in moist air environments: Potential humidity sensors

In moist air environments, the ionic conductivity of polycrystalline Li5AlO4 and Li5GaO4 at 500°C is found to increase 2–3 orders of magnitude in nearly an exponential manner with increasing moisture content (measured for vapor pressures up to ∼ 24 torr). The conductivity rate of response with changing humidity increases with decreasing sample thickness and appears to depend upon the surface-to-volume ratio. Results suggest that these materials may be uniquely suited as humidity sensors for high temperature environments.