First-principles study of the crystal and electronic structures of {alpha}-tetragonal boron

Journal Article · Thu Jul 15 00:00:00 EDT 2010 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.04.036· OSTI ID:21421540

Hayami, Wataru ^[1]; Otani, Shigeki ^[1]

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1. Exploratory Nanomaterials Research Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

The crystal and electronic structures of {alpha}-tetragonal ({alpha}-t) boron were investigated by first-principles calculation. Application of a simple model assuming 50 atoms in the unit cell indicated that {alpha}-t boron had a metallic density of state, thus contradicting the experimental fact that it is a p-type semiconductor. The presence of an additional two interstitial boron atoms at the 4c site made {alpha}-t boron semiconductive and the most stable. The cohesive energy per atom was as high as those of {alpha}- and {beta}-rhombohedral boron, suggesting that {alpha}-t boron is produced more easily than was previously thought. The experimentally obtained {alpha}-t boron in nanobelt form had about two interstitial atoms at the 8i sites. We consider that the shallow potential at 8i sites generates low-energy phonon modes, which increase the entropy and consequently decrease the free energy at high temperatures. Calculation of the electronic band structure showed that the highest valence band had a larger dispersion from {Gamma} to Z than from {Gamma} to X; this indicated a strong anisotropy in hole conduction. - Graphical abstract: Calculated electron densities of B{sub 50} and B{sub 50}+2B at site 4c (configuration B).

• OSTI ID: 21421540
• Journal Information: Journal of Solid State Chemistry, Vol. 183, Issue 7; Other Information: DOI: 10.1016/j.jssc.2010.04.036; PII: S0022-4596(10)00183-0; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
ANISOTROPY
BORON
CRYSTALS
ELECTRON DENSITY
ELECTRONIC STRUCTURE
ENTROPY
FREE ENERGY
INTERSTITIALS
NANOSTRUCTURES
P-TYPE CONDUCTORS
TETRAGONAL LATTICES
TRIGONAL LATTICES
CRYSTAL DEFECTS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELEMENTS
ENERGY
MATERIALS
PHYSICAL PROPERTIES
POINT DEFECTS
SEMICONDUCTOR MATERIALS
SEMIMETALS
THERMODYNAMIC PROPERTIES