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TC03: Glass Structure

The activity of the TC03 committee is focused on the discussion of the basics aspects of glass structure as well as on the experimental collaboration throughout Round Robin tests of model glasses, for which atomistic simulation and thermodynamic modelling techniques are also used. The subject under study of TC03 is also extended to glass microstructure and the relationship between atomic structure and phase separation behaviour. Data on the structure of the Na2O-B2O3-SiO2 glasses under study have already been shared by four different laboratories. In order to investigate the mixing between the silicate and the borate species, advanced techniques such as the through space correlation scheme has been successfully applied. Furthermore, the results of thermodynamic calculations by using the model by N. Vedishcheva and coworkers agree quite well with the experimental data obtained by NMR characterisation. Structural characterisation of the four sodium borosilicate glasses will be completed not only through more advanced NMR methodologies but also with complementary techniques such as FTIR, Raman or XAFS spectroscopy. It has also been thought that Round Robin tests will be extended in a near future to other glass systems of common interest for the members of the committee.

Committee Contact Details: back to top

TC03: Glass Structure

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Committee Members: back to top

Chromcikova, Maria (Dr)
Dalba, Giuseppe (Prof.Dr)
Gedeon, Ondrej (Prof Dr)
Hannon, Alex (Dr)
Kamitsos, Efstratios (Prof)
Karpukhina, Natalia (Dr)
Liska, Marek
Moncke, Doris (Dr)
Montagne, Lionel (Prof Dr)
Munoz, Francisco (Dr)
Committee Chair: Neuville, D.
Saito, Akira (Dr)
Takada, Akira (Prof Dr)
Takebe, Hiromichi (Prof Dr)
Tricot, Gregory (Dr)
Vedishcheva, Natalia (Dr)
Wright, Adrian (Prof Dr)
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Next TC03 technical meeting:  17 May 2015: 2pm in the Room Concerto D Hotel Hilton Miami Downtown.

Activities during 2012

Round-robin test

Structural characterisation of the four sodium borosilicate glasses will be completed not only through more advanced NMR methodologies but also with complementary techniques such as FTIR, Raman or XAFS spectroscopy. It has been thought that Round Robin tests will be extended in a near future to other glass systems of common interest for the members of the committee. Samples of the Na2O-B2O3-SiO2 Round Robin glasses have already been distributed to other laboratories to follow their characterisation. In order to complete the qualitative information about the B-Si connectivity scheme deduced from the 11B{29Si} D-HMQC experiments already performed, the following NMR techniques could be applied:

(i) 11B MQ-MAS : this technique allows reaching the high resolution for the quadrupolar 11B nucleus and could be used to unambiguously determined the number of tri- and tetra-coordinated boron sites. It is worthy to note that these experiments could be performed on the very high static field spectrometer (21.1 T) of the university of Lille.

(ii) B{29Sii} HMQC-ST: at the light of the previous results, a re-investigation of the B-Si correlation could be performed with a correlation techniques providing high resolution for 11B, such as the 11B{29Si} HMQC-ST sequence.

(iii) 11B{29Si} REDOR: a more quantitative investigation will be necessary in order to determine the number of silica connected to each boron species (B(OSi)n). This information could be retrieved from 11B{29Sii} REDOR experiments but will require the preparation of 29Sii-enriched NBS samples. This possibility would also be investigated. It is worth noting that the preparation of the 29Sii-enriched samples will also allow investigating the chemical environment of the different silicate species present in the glass structure. The 29Sii{11B} REAPDOR or RESPDOR techniques could be used to characterise the silica network with the Si(OB4)4-n(OB3)n notation, giving thus access to the medium rage order structure of the glasses. This information could be then used to correlate the structure to the macroscopic properties and to the phase separation process.

Therefore, it has been proposed to continue the investigation of the glass microstructure due to its important influence into the structural speciation. High Resolution TEM characterisation coupled with microanalysis of properly prepared samples will also be scheduled.

Computer modelling of glass structure

Atomistic simulation will be performed to obtain new structural information complementary to the round robin tests and the thermodynamic calculation.

Meeting and symposium

At least one business meeting will be organised during 2012 where most of the members are able to join. In principle, this meeting will be held at the 11 European Society of Glass conference from 3to 6 june 2012 in Maastricht (NL), where the ICG will also celebrate its annual meeting.


Preparation for a course on glass structure to be held during the next ICG Conference in 2013.

TC03 documents

To download annual reports and minutes of meetings please go to

Results on Round Robin tests of NBS glasses

Table I. Samples of four sodium borosilicate glasses, which composition and properties can be found in reference [“Electrical conductivity and viscosity of borosilicate glasses and melts”, D. Ehrt and R. Keding, Physics and Chemistry of Glasses, 50(3), (2009), 165-171] and were prepared by Doris Ehrt in the Otto-Schott Institute (Jena, Germany).

Figure 1. Phase separation in NBS-B (3.0-48.5-48.5) glass. Connected borate-rich droplets with small secondary SiO2 droplets in a SiO2-rich matrix with small secondary borate droplets. By Doris Erht, Otto-Schott Institut für Glaschemie, Friedrich-Schiller Universität Jena (Germany).

Figure 2. Four-fold-coordinate boron fraction N4 values in NBS glasses as determined by Nuclear Magnetic Resonance by Josef Zwanziger (Dalhousie University, Canada) and Scott Kroeker (University of Manitoba, Canada).

Figure 3. 11B{29Si} D-HMQC spectra recorded on the NBS-A (a) and NBS-B (b) samples. In the direct dimension (11B) are reported the 2D spectrum projection (lower part) and the 11B 1D MAS-NMR acquisition (upper part). In the indirect dimension (29Si) is reported the 2D spectrum projection. The 2D spectra have been recorded after 30 and 10 hours of acquisition, respectively, by using the pulse sequence described in references [Trebosc et al., J. Magn. Reson. 186, 2007, 220] and [Tricot et al., Phys. Chem. Chem. Phys 13 (37), 2011, 16786]. Work performed by Gregory Tricot and Lionel Montagne at the NMR facilities of the University of Lille 1 (France).

Table II. Results of N4 fractions in NBS glasses A to D, which compositions are given in Table I, as calculated by the model in [N.M. Vedishcheva et al., J. Non-Cryst. Solids 345&346 (2004) 39-44] by Natalia Vedishcheva. The thermodynamic calculations can reproduce N4 fractions reasonably.

Figure 4. The glasses have also been investigated through molecular dynamics simulation by Akira Takada from Asahi Glass (Japan). The ratio of N4 groups (BO4) was calculated for the four round-robin compositions. The calculated values could reproduced well those estimated from the NMR measurements and from the thermodynamic calculations. The standard MD simulation provided the glass structure close to the ideal mixing of SiO4 and BOn (n=3 or 4) units, probably due to the extremely fast quenching rate. The Figure presents the equilibrium phase diagram with the compositions of the NBS glasses studied by MD simulation as well as the % of boron in BO4 groups with respect to the total of boron atoms as compared with the results obtained by NMR and thermodynamic modeling.

Figure 5. FTIR study on the NBS glasses performed by Hiromichi Takebe at the University of Ehime (Japan).

TC01. Information TC02. Durability & Analysis TC03: Glass Structure Members Contact TC04: Bioglasses TC05: Waste Vitrification TC06: Mechanical & Nanomechanical Properties TC07: Crystallisation & GCs TC09: Energy Efficiency TC10: Optical Properties TC11: Materials for Furnaces TC12: Pharma Packaging TC13: Environment TC14: Gases in Glass TC16: Nanostructures TC17: Achaeometry TC18: Glass Melting TC20 : Optoelectronics TC21: Modelling Melting TC23: Education TC24: Coatings on Glass TC25: Modelling Forming TC26: Structure & Vibrations TC27: Atomistic Simulation

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