Subproject 3: Isotopic effects, jump correlation and diffusion paths in Li-containing oxide glasses
|Supervisor:||Welsch, Behrens, Horn, Bredow|
Diffusion couple experiments will be used to study lithium diffusion in chemically homogenous materials and in systems with a chemical potential gradient. The elemental and isotopic diffusion profiles will be measured using mass spectroscopy coupled with laser ablation (both MC-ICP-MS and Sektorfeld-MS) and then mathematically processed using diffusion equations. The results obtained by impedance spectroscopy combined with the diffusion experiments allow precisely characterizing the correlation factors affecting Li-mobility. The correlation coefficient in solid state materials is determined by defects and by the potential landscape. The interpretation of experimentally obtained correlation coefficients in amorphous systems is challenging. In this respect theoretical modelling will help in identifying the dominant mechanisms of Li-diffusion. Solid state quantum chemical and classical calculations will be performed on simple model systems with a periodical supercell representing structural features of glasses.
Fig.: Arrhenius plots of Li self-diffusion coefficients determined by diffusion couple experiments or calculated from specific conductivity data using the Nernst Einstein relation. A strongly correlated Li-diffusion process in LiAlSi2O6 glass is indicated. (Reprinted with permission from . Copyright 2012 American Chemical Society.)
 B. Ruprecht, J. Heine, M. Wilkening, S. Indris, J. Wontcheu, W. Bensch, T. Bredow, and P. Heitjans, Diff. Fundamentals 12 (2010) 106.
 A.-M. Welsch, H. Behrens, S. Roß, and D. Murawski, Z. Phys. Chem. 226 (2012) 491.
 A.-M. Welsch, H. Behrens, I. Horn, S. Roß, and P. Heitjans, J. Phys. Chem. A 116 (2012) 309.