Investigation of the high pressure phase BiS2: Temperature-resolved structure and compression behavior to 60 GPa

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  • Simone M. Kevy
  • Morten B. Nielsen
  • ,
  • Lars F. Lundegaard, Haldor Topsøe A/S
  • ,
  • Davide Ceresoli, Consiglio Nazionale delle Ricerche
  • ,
  • Yu Sheng Chen, Argonne National Laboratory, Argonne, USA
  • ,
  • Hazel Reardon
  • Paraskevas Parisiades, ID27 Beamline, European Synchrotron Radiation Facility, Institut de Minéralogie de Physique des Matériaux et de Cosmichimie
  • ,
  • Martin Bremholm

BiS 2 was synthesized using a multi-anvil large volume press at a pressure and temperatures of 5.5 GPa and 1250 °C, respectively, and was then recovered at ambient conditions. Using data collection from single crystal synchrotron X-ray diffraction experiments, the crystal structure was found to consist of two distinct distorted square-based pyramidal BiS 5 -units. Synchrotron powder X-ray diffraction in the 85–300 K range shows smooth thermal expansion with a modest anisotropy. Physical property measurements reveals an optical band gap of 1.10 eV and a heat capacity with no anomalies in the 2–300 K range. Debye temperatures, determined by both heat capacity and thermal motion analysis, agree well with values of around 114 and 107 K for Bi1 and Bi2 atoms, respectively. Furthermore, theoretical calculations of the electronic band structure, by density functional theory, confirm the gapped state and reveal a small degree of band inversion at the Γ-point, but calculation of parity eigenvalues show BiS 2 to possess a trivial topology. The high pressure behavior up to 60 GPa was investigated by powder diffraction in a diamond anvil cell; the structure is retained to at least 35 GPa while indications of a structure transition are observed afterwards. Fitting a 3rd order Birch-Murnaghan equation of state for pressures up to 30 GPa gives a bulk modulus of K 0 = 35.5(8) GPa and K 0 ′ = 7.37(18). Finally, a short structural comparison between the high pressure phase of BiS 2 and BiS 2 -based superconductors is presented.

TidsskriftJournal of Alloys and Compounds
Sider (fra-til)588-594
Antal sider7
StatusUdgivet - 15 jun. 2019

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