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The
formation of sp3 bonding in compressed BN |
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| Letters |
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Nature Materials
3,
111–114 (2004) |
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Full Text |
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| YUE MENG1,
2, HO-KWANG MAO2,
PETER J. ENG3,
THOMAS P. TRAINOR3, 5,
MATTHEW NEWVILLE3,
MICHAEL Y. HU1, 2,
CHICHANG KAO4, JINFU SHU2,
DANIEL HAUSERMANN1, 2
and RUSSELL J. HEMLEY2
1 HPCAT, Advanced
Photon Source, Argonne National Laboratory, Argonne,
Illinois 60439, USA
2 Geophysical Laboratory, Carnegie
Institution of Washington, Washington DC 20015, USA
3 GSECARS, University of Chicago, Chicago,
Illinois 60439, USA
4 National Synchrotron Light Source,
Brookhaven National Laboratory, Upton, New York 11973,
USA
5 Present address: Department of Chemistry
and Biochemistry, University of Alaska Fairbanks,
Fairbanks, Alaska 99775, USA
Correspondence to:
YUE MENG ymeng@hpcat.aps.anl.gov
Nature Materials
AOP Published online: 25
January 2004 | doi:10.1038/nmat1060 |
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Attributed to their specific atomic bonding, the soft,
graphite-like, hexagonal boron nitride (h-BN) and its
superhard, diamond-like, cubic polymorph (c-BN) are
important technological materials with a wide range of
applications. At high
pressure and temperature, h-BN can directly transform to
a hexagonal close-packed polymorph (w-BN)
that can be partially quenched after releasing pressure.
Previous theoretical calculations
and experimental measurements (primarily on quenched
samples) provided
substantial information on the transition, but left
unsettled questions due to the lack of in situ
characterization at high pressures. Using inelastic
X-ray scattering to probe the boron and nitrogen near
K-edge spectroscopy, here we report the first
observation of the conversion process of boron and
nitrogen sp2- and p-bonding to
sp3 and the directional nature of the
sp3 bonding. In combination with in
situ X-ray diffraction probe, we have further clarified
the structure transformation mechanism. The present
archetypal example opens two enormous, element-specific,
research areas on high-pressure bonding evolutions of
boron and nitrogen; each of the two elements and their
respective compounds have displayed a wealth of
intriguing pressure-induced phenomena
that result from bonding changes, including
metallization, superconductivity, semiconductivity,
polymerization and
superhardness
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