Revisit: High resolution charge density study of α-rhombohedral boron using third-generation SR data at SPring-8

Nishibori, Eiji; Hyodo, Hiroshi; Kimura, Kaoru; Takata, Masaki

doi:10.1016/j.solidstatesciences.2015.02.007

Cited by 12 publications

(13 citation statements)

References 17 publications

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“…The asymmetric unit features polar atoms B p , which form short and strong (2c,2e) exo-bonds with neighboring icosahedra, as well as equatorial atoms B e forming somewhat weaker (3c,2e) exo-bonds connecting three icosahedra, see Figure 2 . The lengths of the B p -B p and B e -B e exo-bonds (1.66879(14) & 2.00945(19) Å, as obtained from the HCM refinement of experimental structure factors F exp ) are in very good agreement with the single crystal studies of Mondal et al (1.6733(5) & 2.0144(3) Å) as well as the synchrotron powder MEM-studies of Nishibori et al (1.6676(4) & 2.0105(4) Å) [ 45 , 49 ].…”

Section: Resultssupporting

confidence: 88%

“…The new findings were at first in contrast to two earlier independent charge density studies based on synchrotron powder data (sin( θ )/ λ ≤ 0.75 Å −1 ) evaluated by the maximum entropy method (MEM), which suggested a strongly bent nature of the intericosahedral (2c,2e) bond [ 46 , 47 , 48 ]. However, it was shown by Nishibori et al in a synchrotron powder experiment conducted at the beamline BL44B2 (SPring-8, Japan) with resolutions up to sin( θ )/ λ ≤ 1.529 Å −1 at T = 100 K that the earlier powder diffraction results were biased by systematic errors which disappear at resolutions above sin( θ )/ λ ≤ 1.25 Å −1 when the MEM technique is used [ 49 ].…”

Section: Introductionmentioning

confidence: 99%

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The Effects of Chemical Bonding at Subatomic Resolution: A Case Study on α-Boron

2021

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Similar to classical asphericity shifts, aspherical deformations of the electron density in the atomic core region can result in core asphericity shifts in refinements using a Hansen-Coppens multipolar model (HCM), especially when highly precise experimental datasets with resolutions far beyond sin(θ)/λ ≤ 1.0 Å−1 are employed. These shifts are about two orders of magnitude smaller than their counterparts caused by valence shell deformations, and their underlying deformations are mainly of dipolar character for 1st row atoms. Here, we analyze the resolution dependence of core asphericity shifts in α-boron. Based on theoretical structure factors, an appropriate Extended HCM (EHCM) is developed, which is tested against experimental high-resolution (sin(θ)/λ ≤ 1.6 Å−1) single-crystal diffraction data. Bond length deviations due to core asphericity shifts of α-boron in the order of 4–6·10−4 Å are small but significant at this resolution and can be effectively compensated by an EHCM, although the correlation of the additional model parameters with positional parameters prevented a free refinement of all core model parameters. For high quality, high resolution data, a proper treatment with an EHCM or other equivalent methods is therefore highly recommended.

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Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

The Effects of Chemical Bonding at Subatomic Resolution: A Case Study on α-Boron

2021

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“…The cases of silicon and diamond indicate that the MEM charge density analysis of SXPD data is a promising tool to visualize materials properties, e.g. chemical bond and electrostatic properties [5,17,18,[24][25][26][27][28][29][30][31][32]. …”

Section: Charge Density Studiesmentioning

confidence: 99%

Visualizing charge densities and electrostatic potentials in materials by synchrotron X-ray powder diffraction

Kato

Tanaka

2016

Advances in Physics: X

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“…The experimental procedure we developed has been widely applied to accurate charge density studies of materials such as α-boron20, TiO 2 21, Al 2 O 3 21, CoSb 3 2223, silicon24 and diamond2425. The technique successfully determined the detailed charge density features which were quantitatively comparable to those determined theoretically17202122232425. Recently, the charge density studies from ultra-high resolution synchrotron radiation powder diffractions have been reported using an all-in-vacuum diffractometer installed at PETRA-III26.…”

mentioning

confidence: 99%

Spatial distribution of electrons near the Fermi level in the metallic LaB6 through accurate X-ray charge density study

Kasai

Nishibori

2017

Sci Rep

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Charge densities of iso-structural metal hexaborides, a transparent metal LaB6 and a semiconductor BaB6, have been determined using the d > 0.22 Å ultra-high resolution synchrotron radiation X-ray diffraction data by a multipole refinement and a maximum entropy method (MEM). The quality of the experimental charge densities was evaluated by comparison with theoretical charge densities. The strong inter-octahedral and relatively weak intra-octahedral boron-boron bonds were observed in the charge densities. A difference of valence charge densities between LaB6 and BaB6 was calculated to reveal a small difference between isostructural metal and semiconductor. The weak electron lobes distributed around the inter B6 octahedral bond were observed in the difference density. We found the electron lobes are the conductive π-electrons in LaB6 from the comparison with the theoretical valence charge density. We successfully observed a spatial distribution of electrons near the Fermi level from the X-ray charge density study of the series of iso-structural solids.

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Revisit: High resolution charge density study of α-rhombohedral boron using third-generation SR data at SPring-8

Cited by 12 publications

References 17 publications

The Effects of Chemical Bonding at Subatomic Resolution: A Case Study on α-Boron

The Effects of Chemical Bonding at Subatomic Resolution: A Case Study on α-Boron

Visualizing charge densities and electrostatic potentials in materials by synchrotron X-ray powder diffraction

Spatial distribution of electrons near the Fermi level in the metallic LaB6 through accurate X-ray charge density study

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