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Telluride glasses as materials for far-infrared applications : a theoretical and spectroscopic investigation – IRTeGlass

Telluride glasses as materials for far-infrared applications : a theoretical and spectroscopic investigation

Structure of telluride special glasses, transparent in the far infrared domain

Rationalization of the atomic scale structure of tellurium-based glasses exhibiting large infrared transparency windows.

Like most of vitreous materials, the intimate structure of tellurium-based glasses is largely unknown. Therefore, the understanding and optimization of mechanical, optical, and electrical properties of these materials are essentially relying on an empirical set of experimental data and approaches.<br />The aim of the project was to obtain a detailed knowledge of the atomic-scale structure of three families of ternary tellurium glasses: Ge-Te-Se, Ge-Ga-Te and Ge-Te-I, prior to the rationalization of their physical properties. These materials are characterized by very wide infrared transparency windows and exhibit improved stability towards devitrification processes, with respect to the GeTe4 parent composition. Stability improvement of these glasses was achieved by substitution of low levels (typically < 10%) of tellurium with selenium /iodine or germanium with gallium. The rationalization of the specific role of these substituents on the structure of the vitreous matrix was one of the motivations of this project focused on the study of special glasses tuned for infrared applications.

The project relies on two complementary pillars, one experimental and the other theoretical, to achieve its objectives. For the various ternary systems considered, glass samples were produced experimentally and in silico using molecular dynamics calculations. Each bulk sample was acquired using local probe spectroscopic methods (NMR, IR/Raman). These data were then compared to NMR parameter calculations and simulations of IR/Raman spectra performed on our models, in order to rationalize the structure of the materials. Molecular dynamics were finally done within the framework of the Car-Parrinello formalism, which has proven to be more robust than the initially anticipated Second Generation Car-Parrinello method. In the context of heavy element glasses, a validation and calibration phase of the computational formalism has been performed on representative crystalline systems and carried out in order to determine theoretical NMR parameters. A number of crystal test systems have been specifically synthesized for this purpose.

For the study of crystalline systems, a new methodology has been devised that allows to reproduce much more accurately the solid state nuclear magnetic resonance spectra. For amorphous materials, a fine understanding of the structure of ternary Ge-Te-Se glasses, has been achieved combining local probes (NMR, RI/Raman) and ab initio molecular dynamics. Similar progresses have been achieved for Ga-Ge-Te ternary glasses by combining IR/Raman spectroscopy, structure factors and calculations. Another milestone concerns the availability of a new version of the molecular dynamics code incorporating corrections such as an accurate determination of Raman spectra with small gap systems are made possible.

The investigations may be performed on compositions having different Ga / Se or I rates in order to analyze the impact of those ratio on the material structure and properties..

- Impact of Te on the structure and 77Se NMR spectra of Se-rich Ge–Te–Se glasses: a combined experimental and computational investigation
L. Bouëssel du Bourg, C. Roiland, L. le Pollès, M. Deschamps, C. Boussard-Plédel, B. Bureau, C. J. Pickard, E. Furet, Phys. Chem. Chem. Phys. 2015, 17, 29020-29026. DOI: 10.1039/C5CP04416B
- Role of the van der Waals interactions and impact of the exchange-correlation functional in determining the structure of glassy GeTe4
A. Bouzid, C. Massobrio, M. Boero, G. Ori, K. Sykina, E. Furet, Phys. Rev. B 2015, 92, 134208-134228. DOI: 10.1103/PhysRevB.92.134208
- First-principles study of the atomic structure of glassy Ga10Ge15Te75
Z. Chaker, G. Ori, M. Boero, C. Massobrio, E. Furet, A. Bouzid, J. Non-Cryst. Solids, 2018, 498, 338-344 DOI: 10.1016/j.jnoncrysol.2018.03.039
- Study of the Ge20Te80-xSex glassy structures by combining solid state NMR, vibrational spectroscopies and DFT modelling
C. Gonçalves, R. Mereau, Virginie Nazabal, Catherine Boussard-Plédel, Claire Roiland, E. Furet, M. Deschamps, B. Bureau, M. Dussauze
J. Solid State Chem., 2021, 297,.122062. ?10.1016/j.jssc.2021.122062?
- Quantitative assessment of the structure of Ge20Te73I7 chalcohalide glass by first-principles molecular dynamics A. Bouzid, T.-L. Pham, Z. Chaker, M. Boero, C. Massobrio, Y.-H. Shin, and G. Ori Phys. Rev. B 103, 094204

Recently a new generation of ternary telluride glasses in the Ge-Te-Se, Ge-Ga-Te and Ge-Te-I systems have been developed by the “Glass and Ceramics” team of the UMR 6226 laboratory in Rennes. These materials exhibit some of the largest infrared transparency windows reported so far, as well as interesting mechanical properties, for passive optical applications such as remote sensing or thermal imaging.

Incorporation of small amounts, i.e. less than 10%, of gallium, selenium or iodine in the parent composition GeTe4 dramatically increases the glass forming ability and stability towards crystallization of the corresponding materials. The precise role of these elements in the glass matrix is unclear and their impact on the glass structure and physical properties has to be elucidated.

Our project aims at developing a synergetic approach using first-principles molecular dynamics simulations, solid-state NMR parameters calculations, Infrared/Raman simulations, Infrared/Raman and NMR spectroscopies to rationalize the structure and the optical properties of this new generation of tellurium-based far-infrared transmitting glasses.

Project coordination

Eric Furet (Institut des Sciences Chimiques de Rennes)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ISCR Institut des Sciences Chimiques de Rennes
CNRS-IPCMS Institut de Physique et Chimie des Matériaux de Strasbourg
ISM Institut des Sciences Moléculaires
CEMHTI Conditions Extrêmes et Matériaux : Haute Température et Irradiation

Help of the ANR 448,727 euros
Beginning and duration of the scientific project: September 2014 - 36 Months

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