Ionic conductivity of amorphous lithium lanthanum titanate thin film

Amorphous lithium lanthanum titanate (LLT) thin films were prepared by the pulsed laser deposition (PLD) method. By X-ray diffraction measurement of the films, it was confirmed that the crystal structure of the as-prepared thin films was amorphous. The temperature dependence of the ionic conductivity of the amorphous LLT thin film was measured from 300 to 475 K over the frequency region 100 Hz to 10 MHz. The value 0.35 eV was estimated as the activation energy of Li+ ionic conduction in the film in the temperature region 300–475 K. It was revealed that the transfer ratio of Li+ ion for the ionic conduction of the amorphous LLT thin film is over 94%, and the amorphous LLT thin film shows super-ionic conduction at and above room temperature. The conductivity of the LLT thin film was an order of magnitude higher than that of its polycrystalline precursor, mainly due to absence of grain boundary elements and its structural disorder.