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Structural control of ionic conductivity in LiAlSi2O6 and LiAlSi4O10 glasses and single crystals

  • Anna-Maria Welsch , Harald Behrens , Sebastian Ross and Dawid Murawski
Published/Copyright: June 18, 2012

Abstract

In order to better understand the mechanisms of lithium dynamics and to elucidate the influence of defects in lithium mobility, we have studied the Li-ion propagation through natural single crystals of α-spodumene, LiAlSi2O6 and petalite, LiAlSi4O10 using impedance spectroscopy. Electrical conductivity in petalite and α-spodumene is 4–5 orders of magnitude lower than in glasses of the same composition, and three orders of magnitude lower than in synthetic β-spodumene. Conductivity in α-spodumene is anisotropic with conductivity along the c-axis being 0.3–0.4 log units higher than perpendicular to the c-axis. Contrary to α-spodumene, isotropic conductivity was observed for petalite single crystals. Despite the large difference in conductivity values, the activation energies for ionic conduction of α-spodumene along the c-axis (74 to 86 kJ/mol) are only slightly higher than for LiAlSi2O6 and LiAlSi4O10 glasses (∼67 kJ/mol). On the other hand, much higher activation energies of 112–134 kJ/mol were determined for petalite. Based on our investigation, a vacancy-controlled transport mechanism is indicated for the densely packed α-spodumene structure, while in the open framework structure of petalite formation and movement of Li interstitials is proposed to be dominant mechanism for charge transfer.


* Correspondence address: Leibniz Universität Hannover, Institut für Mineralogie, Callinstr. 3, 30167 Hannover, Deutschland,

Published Online: 2012-6-18
Published in Print: 2012-6-1

© by Oldenbourg Wissenschaftsverlag, Hannover, Germany

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