Lithium Diffusion in Ion-Beam Sputtered Amorphous LiAlO2

Abstract

We investigated lithium self-diffusion in amorphous lithium aluminate (LiAlO2) layers between room temperature and 473 K. For the experiments, amorphous 6LiAlO2 (30 nm)/7LiAlO2 (1200 nm) isotope hetero-structures were deposited by ion-beam sputtering on sapphire substrates. Diffusion profiles were analysed by secondary ion mass spectrometry (SIMS). The results show that the diffusivities obey the Arrhenius law with an activation enthalpy of (0.94 ± 0.02) eV. This is not much different to the activation enthalpy of 1.14 eV found for LiAlO2 single crystals by impedance spectroscopy. It rationalizes the only modest enhancement of diffusivities in amorphous lithium aluminate compared to single crystals of three to five orders of magnitude in the temperature range studied, when compared with, e.g., lithium niobate. © 2015 Walter de Gruyter.