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@ARTICLE{Zimmer:407129,
      author       = {Zimmer, Dominik and Ruiz-Fuertes, J. and Morgenroth, W. and
                      Friedrich, Alexandra and Bayarjargal, L. and Haussühl, E.
                      and Santamaría-Pérez, D. and Frischkorn, S. and Milman, V.
                      and Winkler, B.},
      title        = {{P}ressure-induced changes of the structure and properties
                      of monoclinic $\alpha$-chalcocite $\mathrm{{C}u_{2}}{S}$},
      journal      = {Physical review / B},
      volume       = {97},
      number       = {13},
      issn         = {2469-9950},
      address      = {Woodbury, NY},
      publisher    = {APS},
      reportid     = {PUBDB-2018-02407},
      pages        = {134111},
      year         = {2018},
      abstract     = {The high-pressure behavior of monoclinic
                      $(P2_{1}/c)\alpha$-chalcocite, $\mathrm{Cu_{2}}S$, was
                      investigated at ambient temperature by single-crystal x-ray
                      diffraction, electrical resistance measurements, and optical
                      absorption spectroscopy up to 16 GPa. The experiments were
                      complemented by density-functional-theory-based
                      calculations. Single-crystal x-ray diffraction data show
                      that monoclinic $\alpha$-chalcocite undergoes two
                      pressure-induced first-order phase transitions at ∼3.1 and
                      ∼7.1 GPa. The crystal structure of the first high-pressure
                      polymorph, HP1, was solved and refined in space group
                      $P2_{1}/c$ with $a=10.312(4)Å, b=6.737(3)Å, c=7.305(1)Å$,
                      and β=$100.17(2)∘$ at 6.2(3) GPa. The crystal structure
                      of the second high-pressure polymorph, HP2, was solved and
                      refined in space group $P2_{1}/c$ with $a=6.731(4)Å,
                      b=6.689(2)Å, c=6.967(8)Å$, and β=$93.18(3)∘$ at 7.9(4)
                      GPa. Electrical resistance measurements upon compression and
                      optical absorption experiments upon decompression show that
                      the structural changes in α-chalcocite are accompanied by
                      changes of the electrical and optical properties. Upon
                      pressure release, the band gap $Eg$ of $\alpha$-chalcocite
                      (1.24 eV at ambient conditions) widens across the first
                      structural phase transition, going from 1.24 eV at 2.2 GPa
                      (α-chalcocite) to 1.35 eV at 2.6 GPa (HP1), and closes
                      significantly across the second phase transition, going from
                      1.32 eV at 4.4 GPa (HP1) to 0.87 eV at 4.9 GPa (HP2). The
                      electrical resistance shows similar behavior: its highest
                      value is for the first high-pressure polymorph (HP1), and
                      its lowest value is for the second high-pressure polymorph
                      (HP2) of $\alpha$-chalcocite. These results are interpreted
                      on the basis of calculated electronic band structures.},
      cin          = {DOOR / UFrankf.},
      ddc          = {530},
      cid          = {I:(DE-H253)HAS-User-20120731 /
                      $I:(DE-H253)UFrankf_-20120814$},
      pnm          = {6G3 - PETRA III (POF3-622)},
      pid          = {G:(DE-HGF)POF3-6G3},
      experiment   = {EXP:(DE-H253)P-P02.2-20150101},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000429929800002},
      doi          = {10.1103/PhysRevB.97.134111},
      url          = {https://bib-pubdb1.desy.de/record/407129},
}