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Li 2 O at high pressures: structural properties, phase‐transition, and phonons
Author(s) -
Kunc K.,
Loa I.,
Grzechnik A.,
Syassen K.
Publication year - 2005
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200461786
Subject(s) - fluorite , raman spectroscopy , phonon , diffraction , phase transition , crystallography , ab initio , synchrotron radiation , ab initio quantum chemistry methods , phase (matter) , materials science , synchrotron , equation of state , chemistry , thermodynamics , condensed matter physics , molecule , physics , optics , organic chemistry , metallurgy
A structural phase transition in Li 2 O, from the anti‐fluorite to the anti‐cotunnite structure, is evidenced by angle‐dispersive synchrotron X‐ray powder diffraction and supported by ab initio calculations. The equations of state E ( V ), P ( V ) and the enthalpies H ( P ) are determined, for both phases, using total‐energy calculations based on the Projector Augmented Waves method. The calculations supply the value of the transition pressure at T = 0 and in the ‘ideal conditions’ and provide detailed information on all 9 structural parameters describing the anti‐cotunnite structure of Li 2 O at various pressures. We also report Raman frequencies, calculated for both phases and measured in the anti‐fluorite phase, so as to provide a tool for monitoring the approach and the progress of the transformation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)