Abstract
A pressure-induced phase transition of FeOCl is discovered to occur at GPa. It is preceded by extremely anisotropic lattice compression, which is explained by a gradual collapse of the van der Waals gap between the chlorine atoms on the borders of the slabs of this layered compound. Single-crystal x-ray diffraction in a diamond anvil cell is used to show that the high-pressure phase can be described as a fourfold superstructure with monoclinic lattice distortion, described by a supercell with space group ( unique). The high-pressure crystal structures have been used to uncover the mechanism of the phase transition, as the formation of alternating regions of increased packing density of chlorine atoms within a single layer and regions of interpenetrating layers. Raman and Mössbauer spectroscopies indicate that the phase transition is not related to electronic effects or magnetic order.
- Received 28 November 2012
DOI:https://doi.org/10.1103/PhysRevB.88.014110
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