Preparation and ionic conductivity of β-LiAlSiO4 thin film

One-dimensional Li ionic conductor β-LiAlSiO4 (β-eucryptite) thin film was prepared on SiO2 glass (quartz glass) substrates by pulsed laser deposition (PLD) method. It was revealed that a crystal structure of the as-prepared thin film is an amorphous structure, and by annealing above 1000 °C, the thin film shows a β-eucryptite structure. The temperature dependence of ionic conductivity of the β-LiAlSiO4 thin films has been measured for various film thicknesses. A change of activation energy is observed at around 700 K, which is due to the structural phase transition of β-LiAlSiO4. The ionic conductivity of β-LiAlSiO4 thin film increases with a decrease in the film thickness. The conductivity enhancement was considered to have originated from a construction of a high-ionic conduction region at the SiO2-β-LiAlSiO4 boundary.