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@ARTICLE{Friedrich:291398,
      author       = {Friedrich, Alexandra and Winkler, Björn and Morgenroth,
                      Wolfgang and Perlov, Alexander and Milman, Victor},
      title        = {{P}ressure-induced spin collapse of octahedrally
                      coordinated $\mathrm{{M}n^{3+}}$ in the tetragonal
                      hydrogarnet henritermierite
                      $\mathrm{{C}a_{3}{M}n_{2}[{S}i{O}_{4}]_{2}[{O}_{4}{H}_{4}]}$},
      journal      = {Physical review / B},
      volume       = {92},
      number       = {1},
      issn         = {1098-0121},
      address      = {College Park, Md.},
      publisher    = {APS},
      reportid     = {PUBDB-2015-05370},
      pages        = {014117},
      year         = {2015},
      abstract     = {The high-pressure behavior of natural henritermierite
                      garnet with close to end-member composition
                      Ca$_{3}$Mn$_{2}$[SiO$_{4}$]$_{2}$[O$_{4}$H$_{4}$] was
                      studied at pressures up to 80 GPa using single-crystal
                      synchrotron x-ray diffraction, Raman spectroscopy, and
                      quantum-mechanical calculations based on density functional
                      theory. An isosymmetric phase transition was observed in the
                      pressure range between 55 and 70 GPa, which is associated
                      with a gradual high-spin to low-spin electronic transition
                      in Mn$^{3+}$ and a pronounced reduction of the Jahn-Teller
                      distortion of the Mn$^{3+}$O$_{4}$(OH)$_{2}$ octahedra. In
                      the high-pressure phase the Jahn-Teller distortion is
                      totally suppressed and the Mn$^{3+}$ is in a low-spin
                      configuration. Experimental structural data before and after
                      the phase transition are in excellent agreement with the
                      theoretically predicted structural compression of the
                      high-spin and low-spin phases, respectively. While the
                      overall unit-cell volume is reduced by about 1.5\% across
                      the phase transition, a collapse of about 4–5\% of the
                      MnO6 octahedral volume is observed. The high-spin phase
                      shows a bulk modulus B = 101(1) GPa and its pressure
                      derivative B'= 4.5(1). The bulk moduli of the coordination
                      polyhedra are B$_{MnO6}$ = 178(2) GPa, B$_{Ca1O8}$ =
                      101.2(5) GPa, B$_{Ca2O8}$ = 88.4(8) GPa, B$_{SiO4}$= 337(5)
                      GPa, and B$_{O4H4}$ = 29(1) GPa for the high-spin phase.
                      Mode Gr¨uneisen parameters range between 0.34 and 0.94. The
                      computed spin-pairing energy is ≈3.6 eV at 0 GPa.},
      cin          = {DOOR},
      ddc          = {530},
      cid          = {I:(DE-H253)HAS-User-20120731},
      pnm          = {6G3 - PETRA III (POF3-622) / FS-Proposal: I-20130285
                      (I-20130285) / FS-Proposal: I-20140699 (I-20140699)},
      pid          = {G:(DE-HGF)POF3-6G3 / G:(DE-H253)I-20130285 /
                      G:(DE-H253)I-20140699},
      experiment   = {EXP:(DE-H253)P-P02.2-20150101},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000358841400001},
      doi          = {10.1103/PhysRevB.92.014117},
      url          = {https://bib-pubdb1.desy.de/record/291398},
}