Effects of Crystallinity and Impurities on the Electrical Conductivity of Li-La-Zr-O Thin Films

We present a study of the fabrication of thin films from a Li₇La₃Zr₂O₁₂ (LLZO) target using pulsed laser deposition. The effects of substrate temperatures and impurities on electrochemical properties of the films were investigated. The thin films of Li–La–Zr–O were deposited at room temperature and higher temperatures on a variety of substrates. Deposition above 600 °C resulted in a mixture of cubic and tetragonal phases of LLZO, as well as a La₂Zr₂O₇ impurity, and resulted in aluminum enrichment at the surface when Al-containing substrates were used. Films deposited at 600 °C exhibited the highest room temperature conductivity, 1.61 × 10^{− 6} S/cm. The chemical stability toward metallic lithium was also studied using X-ray photoelectron spectroscopy, which showed that the oxidation state of zirconium remained at + 4 following physical contact with heated lithium metal.