Glass - Back to the Future!



Presenting Author:
Jana Holubova
<jana.holubova@upce.cz>

article posted 28 March 2016


Jana Holubová is an associate professor at Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Czech Republic.

She graduated with a degree in physical chemistry from Faculty of Science, Charles University in Prague, Czech Republic and received PhD degree in inorganic chemistry at University of Pardubice in 1996.

Her research is focused on the structure, thermal behavior and some other physical and chemical properties of chalcogenide and phosphate based glasses.






Structural Investigation and Properties of
Gallium Zinc Phosphate Glasses

Jana Holubova1*, Zdenek Cernosek1, Eva Cernosková2

Phosphate glasses, especially glasses based on zinc-phosphate, are being intensively studied during recent years because they provide some unique physical properties compared to silicate glasses, such as low melting temperature, high coefficient of thermal expansion and low optical dispersion. The introduction of various metal oxides results in variability of their physical and chemical properties, gallium trioxide has received attention because of improving chemical durability and of antibacterial properties. The aim of our work was to study the effect of substitution of zinc by gallium on some physico- chemical properties of phosphate glasses, as well as on their structure.

The glasses of ternary gallium zinc phosphate system have been prepared by a conventional melt-quenching method in two compositional series:
A: xGa2O3-(50-x)ZnO- 50P2O5
(x = 0, 3, 5, 10, 13, 15, 20, 25, 30)
and B: yGa2O3-(50-2y)ZnO-(50+y)P2O5
(y = 0, 5, 10, 15, 20, 25),
the last one is a metaphosphate profile. The homogeneous glasses were prepared in the whole concentration regions.



Thermal properties of glasses were studied by differential thermal analysis (DTA) and thermomechanical analysis (TMA). Addition of Ga2O3 results in increase of density, glass transition temperature and microhardness of studied glasses, while the coefficient of thermal expansion decreases.



The effect of successive replacement of zinc by gallium on basic phosphate structure has been evaluated using Raman spectroscopy, 31P MAS and static NMR and 71Ga MAS NMR was used for monitoring of of changes of gallium Oh vs Td coordination.

In glasses of series A the coordination of Ga3+ change from six-coordination to four-coordination with increasing content of Ga, in series B only octahedral coordination was found. Chemometrical analysis, namely multivariate curve resolution (MCR) and correlation spectroscopy was also used to obtain detailed information on structure from Raman scattering and both type of 31P NMR spectra.

Institutions:

1 Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic,

2 Joint Laboratory of Solid State Chemistry of Institute of Macromolecular Chemistry of Czech Academy of Sciences, v.v.i., and University of Pardubice, Pardubice, Czech Republic