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TT: Fachverband Tiefe Temperaturen
TT 33: CE: Metal-Insulator Transition 1
TT 33.9: Vortrag
Mittwoch, 16. März 2011, 12:45–13:00, HSZ 105
Two Pressure-induced structural phase transitions in TiOCl — •Jihaan Ebad-Allah1, Andreas Schoenleber2, Sander van Smaalen2, Michael Hafland3, Mattias Klemm1, Siegfried Horn1, Sebastian Glawion4, Michael Sing4, Ralph Claessen4, and Christine Kuntscher1 — 1Experimentalphysik II, Universität Augsburg, 86159 Augsburg, Germany — 2Laboratory of Crystallography, Universität Bayreuth, 95440 Bayreuth, Germany — 3European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble, France — 4Experimentelle Physik 4, Universität Würzburg, D-97074 Würzburg, Germany
The titanium oxyhalides TiOX (with X=Cl or Br) are
low-dimensional materials which undergo an unconventional transition
to a spin-Peierls state via a structural incommensurate state. With
the electronic configuration 3d1 these compounds are
Mott-Hubbard insulators with a charge gap of ≈2 eV. As a
follow-up to our recent investigations on TiOX [1], we studied the
crystal structure of TiOCl by powder X-ray diffraction measurements
at room temperature up to high pressures of p≈25 GPa.
Besides a phase transition at pc1≈15 GPa from the
orthorhombic Pmmn to the monoclinic P21/m crystal structure
with a 2a×2b×c superstructure, we find a
pressure-induced isostructural phase transition
pc2≈22 GPa for the monoclinic phase with anomalies in
the lattice parameters [2].
C. A. Kuntscher et al., Eur. Phys. J. Special Topics 180,29 (2010).
J. Ebad-Allah et al., Phys. Rev. B 82, 134117
(2010).