Lithium Diffusion in Ion-Beam Sputtered Amorphous LiAlO₂

Abstract

Abstract:We investigated lithium self-diffusion in amorphous lithium aluminate (LiAlO 2 ) layers between room temperature and 473 K. For the experiments, amorphous 6 LiAlO 2 (30 nm)/ 7 LiAlO 2 (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 LiAlO 2 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.

NMR and Impedance Spectroscopy Studies on Lithium Ion Diffusion in Microcrystallineγ-LiAlO2

“…The Li diffusivities of the nanocrystalline -LiAlO 2 samples reported in the literature [20] are also higher than those presented here for the microcrystalline form, and the activation energy varies from 0.78 to 1.14 eV depending on the milling time. So the overall diffusion behavior in different structural forms (single crystalline, microcrystalline, nanocrystalline and amorphous) seems to be qualitatively similar to that in the extensively studied model system LiNbO 3 [32,35,36], although the diffusivity enhancements in the amorphous forms in the two systems differ quantitatively [31]. To sum up, the diffusion results obtained here on microcrystalline -LiAlO 2 are shown in Figure 8.…”

“…Secondary ion mass spectrometry (SIMS) showed a similar activation energy of 0.9 eV for amorphous LiAlO 2 [31]. As expected, the values of diffusion coefficients occurred to be higher in the amorphous material than in the microcrystalline form despite the similar activation energies.…”

Slow Lithium Transport in Metal Oxides on the Nanoscale

“…The samples were characterized between room temperature and 473 K [83]. Diffusion profiles were analysed by SIMS.…”

Phonons and lithium diffusion in LiAlO2

“…The authors explained the difference in barrier energy between these two forms of sample with the presence in larger concentrations of defects and vacancies in the powder sample than in the single crystal. The study in amorphous LiAlO2 from room temperature and 473 K showed 37 that the lithium diffusivity obeys the Arrhenius law with an activation energy of 0.94 eV and significantly higher Li diffusion coefficient 3.6 ×10 -15 m 2 /sec at 473K , which is three order of magnitude higher than in crystalline phase (~10 -18 m 2 /sec) at same temperature 28 . A study on disordered γ-LiAlO2 showed that the introduction of structural disorder significantly enhances the Li ion conductivity in γ-LiAlO2 26 . Several new solid superionic electrolytes have been discovered in which the diffusion mechanism is found to be strongly correlated with the rotational dynamics of constituent polyhedra 38 .…”