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Synthesis and Microdiffraction at Extreme Pressures and Temperatures
Published on: October 7, 2013
The structural behaviour of LaF(3) at high pressures
Wilson A Crichton1, Pierre Bouvier, Bjoern Winkler
1European Synchrotron Radiation Facility, 6 rue Jules Horowitz, B. P. 220, F-38043, Grenoble cedex, France. crichton@esrf.fr
Dalton Transactions (Cambridge, England : 2003)
|April 28, 2010
Summary
High pressure studies reveal lanthanum trifluoride (LaF3) adopts an anti-Cu(3)Ti-type structure. This structure is stable to at least 60 GPa, supporting transition mechanisms for rare earth trifluorides.
Area of Science:
- Materials Science
- Solid-State Chemistry
- High-Pressure Physics
Background:
- Lanthanum trifluoride (LaF3) exhibits complex structural behavior under high pressure.
- Previous studies proposed I4/mmm and Cmma symmetries for LaF3 phases.
- Understanding these transitions is crucial for rare earth trifluoride (REF3) materials.
Purpose of the Study:
- To investigate the high-pressure structure and behavior of LaF3.
- To clarify the phase transition mechanisms and structural symmetries.
- To determine the stability range of the high-pressure phases.
Main Methods:
- In situ X-ray diffraction and Raman scattering experiments.
- Pseudosymmetry analysis of crystallographic structures.
- Quantum mechanical atomistic simulations.
Main Results:
- The high-pressure phase of LaF3 (LaF3-II) is best described by the anti-Cu(3)Ti-type structure (oP8, Pmmn, SG59).
- This structure is closely related to simulated I4/mmm and previously reported Cmma symmetries.
- LaF3-II remains stable up to at least 60 GPa, with no further transitions expected before 1 Mbar.
Conclusions:
- The anti-Cu(3)Ti-type structure provides a consistent model for LaF3-II.
- The findings support atomistic simulation-derived transition mechanisms for REF3 to the post-tysonite phase.
- This research clarifies the high-pressure structural evolution of LaF3 and related materials.
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