Investigation of the structure of lithium borate ionic glasses

Author(s)

Christoph Tietz

Abstract

Alkali borate glasses are well known fast ion conductors with various applications. Lithium
borate glasses show the highest mobility between alkali borates and are eligible candidate
for studying fast ionic motion mechanisms in glasses. The preferred new experimental
technique for such studies is called atomic scale X-ray photon correlation spectroscopy
(aXPCS).
As outlined in the brief introduction into aXPCS given by Ross[9], knowledge of the ionion
partial structure factor is essential for the data analysis of the aXPCS measurement.
The investigation of the short-range order of lithium borate glasses is therefore seen in the
prospect of future aXPCS measurements previously performed for rubidium[10], potassium
and sodium borate glasses.
The goal of this Master’s thesis was to perform preliminary experimental studies and
computer simulations of short-range order (SRO) of lithium borate glasses as an introductory
stage for future synchrotron experiments. SRO of lithium borate glasses was
investigated by X-ray scattering. Three lithium glass samples with different alkali content
were prepared in our laboratory and investigated by small-angle X-ray scattering
(SAXS) as well as wide-angle X-ray scattering (WAXS) techniques. Measuring with the
WAXS set-up allowed the measurement of the first two diffraction peaks. Not too much
quantitative results could be extracted from the SAXS measurement yet some qualitative
information about large scale inhomogeneities have been gained.
The Monte Carlo simulations allow detailed investigation of structural properties like
spatial correlations, angle distributions, coordination number, the abundance of tetrahedrally
coordinated boron atoms, partial structure factors and the Faber-Ziman structure
factor. A well established Born-Mayer-Huggins type pair potential in conjunction with a
three-body potential was used to run Monte Carlo simulations in the canonical ensemble.
Different quantities obtained from my simulations were compared with literature results,
both experimental and simulated using Molecular Dynamics (MD) method. Similarities
and discrepancies between these methods, i.e. between MC and MD technique, allowed to
draw interesting conclusions about strengths and weaknesses of both types of computer
simulations.

Organisation(s)

Dynamics of Condensed Systems

No. of pages

77

Publication date

11-2015

Austrian Fields of Science 2012

103018 Materials physics, 103009 Solid state physics, 103015 Condensed matter

Keywords

Portal url

https://ucris.univie.ac.at/portal/en/publications/investigation-of-the-structure-of-lithium-borate-ionic-glasses(ff09d8bf-904c-46e3-b3f2-8f6426916e73).html