Investigating Alkali Borate Glasses via Total X-ray scattering

Katharina Holzweber, Bogdan Sepiol

Within the scope of this thesis the structure of alkali borate glasses is investigated by total scattering experiments. Different approaches in sample preparation, experimental setups and evaluation procedures are tested and the results are compared. In the first chapter an introduction into the current state of research is given where results both from experiments and computer simulations are considered. In contrast to previous works which focused on selected alkali oxides or concentrations this work analyzes and compares the whole range of alkali oxides with different concentrations, starting from lithium oxide to caesium oxide.

A comprehensive theoretical background about polyatomic systems regarding the structure factor and the partial distribution function is provided in the second chapter together with a short introduction into X-ray diffraction theory. The former is required for an optimal application of the evaluation program PDFgetX and a correct analysis of the experimental results.

Additionally, it is pointed out that without the support of numerical simulations, a complete deciphering of polyatomic systems consisting of several partial structure factors and pair distribution functions is impossible or at least very elaborate, by experimental means. Nonetheless, one can still determine the alteration of the alkali borate structure with respect to interatomic distances and coordination numbers for different alkali concentrations or alkali types.

Some deficits of the highly automatable successor program PDFgetX3 for the evaluation of alkali borate glasses were shown and documented in detail.
The manufacturing process of alkali borate glasses and the preparation of thin platelets and powder samples are precisely explained in the chapter about the experimental approach. Due to the hygroscopic nature of alkali borate glasses which leads to crystallization on the surface, the usage of platelets is advantageous due to their small surface-area-to-volume ratio.

In the last chapter the results of the measurements at Petra III at the Deutsches
Elektronensynchrotron (DESY) in Hamburg and at the Empyrean PANalytical Xray
diffractometer at the TU Wien were analyzed. The profound structural analysis of alkali borate glasses, which is provided by this Master’s thesis, is a good basis for further investigations concerning diffusion processes within these materials via X-ray photon correlation spectroscopy measurements.

Dynamics of Condensed Systems
Publication date
Austrian Fields of Science 2012
103008 Experimental physics, 103009 Solid state physics, 103015 Condensed matter, 103018 Materials physics
ASJC Scopus subject areas
Condensed Matter Physics
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