MASTER DE PHYSIQUE ET APPLICATIONS Spécialité Sciences des Matériaux et Nano-objets

International Nanomat Master Program

Master thesis proposal (M2) 2016-2017

Laboratory: Institut de Minéralogie, Physique des Matériaux et Cosmochimie (IMPMC) Institution: UPMC, Campus Jussieu.Address: 4, Place Jussieu, 75005 ParisLaboratory director: Guillaume Fiquet

Internship supervisor: Guillaume FerlatPhone: 01 44 27 98 22e-mail: ferlat@impmc.upmc.fr website: http://www-ext.impmc.upmc.fr/~ferlat/

Techniques in use: molecular dynamics simulations (possibly: neutron diffusion experiments)Applicant skills: strong background in solid-state physics, propensity for simulations Key words: structure, oxide, glasses, atomistic simulations

Granted internship: Y Matisse labex team: YPossibility for a thesis: Y

Microscopic structure and anomalies in borate glasses

Borates (such as (M2O)x-(B2O3)1-x where M is an alkali metal) enter in the composition of many technologically-important materials: electrolytes, waste glasses, bioactive materials, etc. From a fundamental point of view, the originality of borates, as compared to other glasses such as silicates, lies in the fact that boron can adopt several coordination states ([3]B or [4]B at ambient pressure) depending on the temperature and/or alkali concentration: this gives rise to original topological networks, which are made by both 2D (figure (a)) and 3D (figure (b)) super-structural units. These structural aspects, although still poorly known, are essential to understand the many anomalies (density maxima, Tg minima) and several spectacular variations of the properties with the alkali concentration (figure (c)).

The aim of this project is to determine the microscopic structure of lithum borate glasses (for various compositions) in order to establish correlations with their macroscopic properties (in particular, their rigidity) by using both experiments (neutron diffusion) and atomistic simulations (molecular dynamics). The candidate will analyse previously acquired data and complement them with new ones. The project can be extended to a PhD with a particular focus on either experiments or simulations depending on the candidate’s interests.

[1] G. Ferlat et al., Phys. Rev. Lett. 101, 065504 (2008) ; [2] G. Ferlat et al., Nature Materials, 11, 925 (2012)

[3] A. Zeidler et al., Phys. Rev. B, 90, 024206 (2014) [4] O. Alderman et al., J. Phys. : Condens. Matter, 27 455104 (2015)