High-pressure structural studies of group-15 elements

Degtyareva, Olga; McMahon, M. I.; Nelmes, R. J.

doi:10.1080/08957950412331281057

Cited by 104 publications

(127 citation statements)

References 60 publications

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“…The corresponding mode Grüneisen parameters γ given in Table I were estimated using a bulk modulus value of B 0 = 100 GPa as extracted from pressure-volume data given in Ref. 7.…”

Section: A7mentioning

confidence: 99%

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Effect of pressure on the Raman modes of antimony

et al. 2006

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The effect of pressure on the zone-center optical phonon modes of antimony in the A7 structure has been investigated by Raman spectroscopy. The Ag and Eg frequencies exhibit a pronounced softening with increasing pressure, the effect being related to a gradual suppression of the Peierls-like distortion of the A7 phase relative to a cubic primitive lattice. Also, both Raman modes broaden significantly under pressure. Spectra taken at low temperature indicate that the broadening is at least partly caused by phonon-phonon interactions. We also report results of ab initio frozenphonon calculations of the Ag and Eg mode frequencies. Presence of strong anharmonicity is clearly apparent in calculated total energy versus atom displacement relations. Pronounced nonlinearities in the force versus displacement relations are observed. Structural instabilities of the Sb-A7 phase are briefly addressed in the Appendix.

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“…The corresponding mode Grüneisen parameters γ given in Table I were estimated using a bulk modulus value of B 0 = 100 GPa as extracted from pressure-volume data given in Ref. 7.…”

Section: A7mentioning

confidence: 99%

“…intermediate between Sb-I and Sb-II. 7,8 Here we are interested mainly in the effect of pressure on optical phonon modes of the A7 phase of Sb. The A7 structure (Fig.…”

Section: Introductionmentioning

confidence: 99%

Effect of pressure on the Raman modes of antimony

et al. 2006

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“…1,2 As a result, the A7 structure has rhombohedral crystal symmetry and is a small distortion removed from simple cubic symmetry, which can be experimentally accessed under applied pressure. [3][4][5][6] These structures are shared and expanded by nine compounds with average Group V: the equiatomic compounds between Group IV (Ge, Sn, Pb) and Group VI (S, Se, Te). 7,8 The band structure that drives formation of the A7 phase also causes these elements to be the prototypical semimetals, with a small offset band overlap, small number of carriers compared to typical metals (10 −5 as many), high mobility, and nearly equal concentrations of electron and hole carriers.…”

Section: Introductionmentioning

confidence: 99%

Chemical ordering rather than random alloying in SbAs

Shoemaker

Chasapis

et al. 2013

Phys. Rev. B

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The semimetallic Group V elements display a wealth of correlated electron phenomena due to a small indirect band overlap that leads to relatively small, but equal, numbers of holes and electrons at the Fermi energy with high mobility. Their electronic bonding characteristics produce a unique crystal structure, the rhombohedral A7 structure, which accommodates lone pairs on each site. Here we show via single-crystal and synchrotron x-ray diffraction that SbAs is a compound and the A7 structure can display chemical ordering of Sb and As, which were previously thought to mix randomly. Formation of this compound arises due to differences in electronegativity that are common to IV-VI compounds of average group V such as GeTe, SnS, PbS, and PbTe, and also ordered intra-period compounds such as CuAu and NiPt. High-temperature diffraction studies reveal an order-disorder transition around 550 K in SbAs, which is in stark contrast to IV-VI compounds GeTe and SnTe that become cubic at elevated temperatures but do not disorder. Transport and infrared reflectivity measurements, along with first-principles calculations, confirm that SbAs is a semimetal, albeit with a direct band separation larger than that of Sb or As. Because even subtle substitutions in the semimetals, notably Bi1−xSbx, can open semiconducting energy gaps, a further investigation of the interplay between chemical ordering and electronic structure on the A7 lattice is warranted.

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“…These high pressure regions with the strained lattice probably cannot be detected by X-ray diffractometry because the strain regions are only a few atomic layers thick and do not contribute much to the signal from the sample. Bi under high pressure is known to turn superconducting due to the formation of highpressure metallic polymorphs, namely, monoclinic Bi-II at 2.55 GPa (Brugger et al, 1967;Degtyareva et al, 2004;Nédellec et al, 1974), a complex tetragonal Bi-III at 2.7 GPa (Degtyareva et al, 2004;Haussermann et al, 2002), and a body centered cubic (bcc) Bi-V at 7.7 GPa. (Chen et al, 1969;Degtyareva et al, 2004).…”

Section: New Superconducting Materials -Bismuthmentioning

confidence: 99%