Mercury Sulfide Dimorphism in Thioarsenate Glasses

Mohammad Kassem (1) , Anton Sokolov (1) , Arnaud Cuisset (1) , Takeshi Usuki (2) , Sohayb Khaoulani (1) , Pascal Masselin (1) , David Le Coq (3) , M. Feygenson (4) , C. J. Benmore (5) , Alex C Hannon (6) , J. C. Neuefeind (4) , Eugene Bychkov (1)

1 LPCA - Laboratoire de Physico-Chimie de l'Atmosphère
2 YAMAGATA UNIVERSITY
3 ISCR - Institut des Sciences Chimiques de Rennes
4 Neutron Sciences Directorate [Oak Ridge]
5 XSD - X-ray Science Division
6 MIT, Dept Mat Sci & Engn, Cambridge

Crystalline mercury sulfide exists in two drastically different polymorphic forms in different domains of the P,T-diagram: red chain-like insulator α-HgS, stable below 344 °C, and black tetrahedral narrow-band semiconductor β-HgS, stable at higher temperatures. Using pulsed neutron and high-energy X-ray diffraction, we show that these two mercury bonding pattern are present simultaneously in mercury thioarsenate glasses HgS-As2S3. The population and interconnectivity of chain-like and tetrahedral dimorphous forms determine both the structural features and fundamental glass properties (thermal, electronic, etc.). DFT simulations of mercury species and RMC modelling of high-resolution diffraction data provide additional details on local Hg environment and connectivity implying the (HgS2/2)m oligomeric chains (1 ≤ m ≤ 6) are acting as a network former while the HgS4/4-related mixed agglomerated units behave as a modifier

Domaines: Matériaux; Matériaux

Mohammad Kassem, Anton Sokolov, Arnaud Cuisset, Takeshi Usuki, Sohayb Khaoulani, et al.. Mercury Sulfide Dimorphism in Thioarsenate Glasses. Journal of Physical Chemistry B, 2016, 120 (23), pp.5278 - 5290. ⟨10.1021/acs.jpcb.6b03382⟩. ⟨hal-01426924⟩