Low temperature synthesis and ionic conductivity of the epitaxial Li0.17La0.61TiO3 film electrolyte

Abstract

Epitaxial thin films of the lithium ionic conductor Li_0.17La_0.61TiO₃ have been successfully synthesized on Al₂O₃(0001) and Nb:SrTiO₃(001) substrates at working temperatures below 750 °C using pulsed laser deposition. The application of high laser fluence in conjunction with low oxygen pressure was identified as the key to obtaining highly crystalline Li_0.17La_0.61TiO₃ films. The use of low temperatures prevents the loss of lithium during the deposition process and generates films with no compositional deviation from the target, as confirmed by chemical analyses. The Li_0.17La_0.61TiO₃ film deposited on Al₂O₃(0001) exhibits a high total ionic conductivity of 3.76 × 10⁻⁴ S cm⁻¹ at room temperature, which is comparable to the bulk ionic conductivity of polycrystalline Li_0.18La_0.61TiO₃. The low temperature synthetic process described herein should allow the use of new configurations to fabricate electrode–electrolyte interfaces for use in high power all solid-state batteries incorporating Li_0.17La_0.61TiO₃ as the solid electrolyte.