Pressure-driven evolution of the covalent network in CaB 6

A. N. Kolmogorov, S. Shah, E. R. Margine, A. K. Kleppe, A. P. Jephcoat

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)


We synthesized and solved an unexpectedly complex crystal structure of CaB 6 under high pressures (up to 44 GPa) and temperatures. The only known crystal structure in the large family of metal hexaborides, a simple cubic cP7 type discovered over 80 years ago, is shown here to transform into a tetragonal tI56 configuration comprised of unfamiliar 24-atom boron units. The interpretation of the convoluted x-ray diffraction pattern was accomplished with an ab initio evolutionary search which identified the tI56 structure (28 atoms per primitive unit cell) without any parameter input. The exotic CaB 6 phase was successfully quenched down to ambient pressure.

Original languageEnglish
Article number075501
JournalPhysical Review Letters
Issue number7
Publication statusPublished - Aug 16 2012

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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