Pressure induced dimer to ionic insulator and metallic structural changes in Al2Br6

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Journal titleJournal of Chemical Physics
Article number94501
SubjectElectron phonon couplings; Experimental datum; Fermi surface nesting; First-principles density-functional method; High-pressure phase transitions; Mechanically stable; Structural transformation; Superconducting critical temperatures; Dimers; Electronic structure; Phonons; Aluminum
AbstractHigh-pressure phase transitions in Al2Br6 were theoretically investigated using first principles density functional methods. A structural transformation from the initial molecular solid phase to a planar polymeric phase is predicted near 0.4 GPa that is accompanied with a substantial volume drop. A unique feature of this phase transition is that the hcp lattice of Br atoms remains unchanged during the transition, whereas the Al atoms are displaced from the original tetrahedral sites to the octahedral sites. The calculated phonon spectra indicate that the predicted phase is mechanically stable at 1 atm, and therefore it may be quench-recovered to ambient conditions and exist as a metastable form. A second structural transformation is predicted to occur at around 80 GPa, and also at this point, the AlBr3 reaches a metallic state. The electronic structure of the metallic phase features soft phonon modes and Fermi surface nesting in the Brillouin zone, which leads to localized electron-phonon coupling. By comparing with the experimental data available for high-pressure BI3, the superconducting critical temperature Tc for the metallic phase of AlBr3 is estimated to be at 0.5 K or above.
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AffiliationSecurity and Disruptive Technologies; National Research Council Canada
Peer reviewedYes
NPARC number21270472
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Record identifiere79870db-6a87-4d20-b251-58d685dbedb0
Record created2014-02-12
Record modified2017-03-23
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