Glass - Back to the Future!

Presenting Author:
Ladislav Koudelka

article posted 6 April 2016

Ladislav Koudelka is the professor of Materials Science of the Faculty of Chemical Technology at the University of Pardubice, Czech Republic. From the 1970s to 90s he was involved in the studies of chalcogenide glasses, especially their structure, using the methods of vibrational spectroscopy. From the 1990s he studies phosphate and borophosphate glassy and crystalline materials and their structure by Raman and NMR spectroscopy. He organized International Conference on Borate and Phosphate Glasses in Pardubice 2014. From 2011 he is a vice-chairman of Czech Glass Society.

Structural studies of barium borophosphate glasses by Raman and NMR spectroscopies

Ladislav Koudelka1*, Petr Kalenda1, Petr Mošner1, Lionel Montagne2 & Bertrand Revel2
1 University of Pardubice, Faculty of Chemical Technology, 53210 Pardubice, Czech Republic
2 University of Lille, CNRS, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille, France

Fourteen glasses of the BaO–B2O3–P2O5 system from the glass-forming region of ternary system BaO–B2O3–P2O5 were prepared at 1000–1400°C in platinum crucibles by slow cooling in air. Their glass structure was investigated by 31P and 11B MAS NMR and by Raman spectroscopies. The obtained results were evaluated in five compositional series: A – (100-x)Ba(PO3)2xB2O3, B – 40BaO–yB2O3–(60-y)P2O5, C – (50-z)BaO–zB2O3–50P2O5, D – (60-w)BaO–wB2O3–40P2O5 and E: uBaO–40B2O3–(60-u)P2O5 with 0–40 mol% B2O3 (see enclosed figure). Their thermal behavior was studied by DTA, hot-stage microscopy and dilatometry. The glass transition temperature increases with increasing B2O3 content in all four compositional series within the range of 296–615°C. Barium borophosphate glasses are transparent in the wavelength range of 300–2000 nm and their index of refraction varies within 1·63–1·65. 31P MAS NMR spectroscopy showed on the shortening of phosphate chains due to the incorporation of borate structural units most steeply in the series 40BaO–yB2O3–(60-y)P2O5. Raman spectra in this series also showed on the transformation of phosphate units in the direction Q3->Q2->Q1->Q0 with an increasing B2O3 content. 11B MAS NMR spectra showed that in glasses containing 0-20 mol% B2O3 boron atoms predominantly form tetrahedral BO4 units, while the fraction of BO3 units does not exceed 4%. In the glasses with 10–40 mol% B2O3 the formation of B–O–B linkages was revealed from 11B NMR spectra and their number increases with increasing B2O3 content and decreasing P2O5 content. By the decomposition of the 11B MAS NMR spectra it is possible to estimate the fractions of basic structural units formed by boron - B(OP)3O, B(OP)2O2 and BO3 in all glasses of the glass forming region.