Natalia M. Vedishcheva
<ionatali386@gmail.com>

 

 

 

 


If you would like to present a paper or poster, please email us at:
<abstracts@sgt.org>
You’ll find there’s a convenient template
<here>

 

A comparison of lithium borate glasses and crystals: A thermodynamic approach
Natalia M. Vedishcheva
Institute of Silicate Chemistry of the Russian Academy of Sciences, Nab. Makarova 2,
St. Petersburg, 199034, Russia

It is known that, in lithium borate glasses, the short-range order is determined by the presence of basic structural units, viz. boron-oxygen tetrahedra and triangles with (NBOs) and without non-bridging oxygen atoms, and the intermediate-range order is characterised by a set of various superstructural units (rings). A thermodynamic approach, based on the model of associated solutions, together with information about the structure of thermodynamically stable crystals in the system (Li2O.3B2O3, Li2O.2B2O3, Li2O.B2O3, 3Li2O.2B2O3 and 2Li2O.B2O3), is used for calculating the distribution of the basic structural units and superstructural rings in glasses containing up to 70 mol. % Li2O. The calculated concentration dependence of the content of boron-oxygen tetrahedra is in good agreement with the experimental data available in the literature. An analysis of this dependence, in terms of the concept of chemical structure, enables some of the structural features experimentally found in glasses as compared to crystals [1], to be quantitatively explained. Among them are an excess number of NBOs in glasses containing more than 20 mol. % Li2O, and a deficit of NBOs in glasses in the region above 50 mol. % Li2O. This approach also allows the polymerization degree of the borate network to be analysed as a function of the glass composition.

Reference:
G. Lelong et al. Journal of Non-Crystalline Solids 472 (2017) 1–8