A.C. Impedance Studies of Glassy and Crystalline Lithium Aluminosilicate Compounds

Abstract

A.C. impedance spectroscopy was used to characterise the electrical conductivity behaviour of polycrystalline β‐LiAlSi2O6, β‐LiAlSiO4 and the corresponding glasses with identical stoichiometric compositions. Two bulk conduction processes with different activation energies were detected for β‐LiAlSiO4. The dispersion in the conductivity of the samples, the non‐Debye conductivity relaxation and the frequency dependence of the a.c. activation energies are discussed. The problem of how best to compare data from impedance measurements with results obtained from NMR relaxation experiments is addressed. It was found that diagrams of log resistivity against reciprocal temperature, plotted for individual frequencies, are suitable for comparing directly with NMR data.

Ion hopping in crystalline and glassy spodumeneLiAlSi2O6:Qi1, Rier2, Böhmer3 et al. 2005Phys. Rev. BSelf Cite

“…These values can be compared to the ones determined from conductivity measurements which yielded 0.80 eV for the crystal and 0.66 eV for the glass. 4 These numbers essentially agree with the activation energies from the high-temperature sides of the asymmetric peaks in the log T 1 −1 vs 1 / T plot ͑cf. Fig.…”

“…The properties of polycrystalline and of amorphous material with the same chemical composition were, e.g., explored in comparative studies on LiAlSi 2 O 6 glass and ␤-spodumene ͑␤-LiAlSi 2 O 6 ͒ polycrystals using NMR and conductivity spectroscopy. 3,4 In the present article we focus on 7 Li NMR, which is a valuable tool for the study of dynamics in various ion conducting materials; for reviews see, e.g., Refs. 5 and 6.…”

“…One-third of the silicon atoms is replaced by aluminum atoms at random. The charge of an AlO 4 − group is in each case compensated by a lithium ion. The structure shows zeolite like channels.…”

Test of universal scaling of ac conductivity in ionic conductors

“…In view of this failure and in order to salvage the situation, one might have to resort to the argument that the proposed equation ͑6͒ is applicable to glassy or molten ionic conductors and not to crystalline ionic conductors. Nonetheless, the conductivity relaxation data of crystalline ionic conductors 13,15,16,30,31 exhibit the same characteristics of glassy and molten ionic conductors. Thus, at least from a phenomenological point of view the conductivity relaxation mechanism is the same and whatever theory or model proposed for one should apply to the other.…”

Studying Li Dynamics in a Gas-Phase Synthesized Amorphous Oxide by NMR and Impedance Spectroscopy

“…5b the relatively low Li ion diffusivity and ion conductivity, respectively, found here is compared with results on crystalline and glassy eucryptite LiAlSiO 4 [71] as well as glassy spodumene LiAlSi 2 O 6 [72] (see also Refs. [73,74]). Interestingly, although the sample studied turns out to be X-ray amorphous, ion conductivities probed resemble that of crystalline LiAlSiO 4 rather than that of the glassy counterpart.…”