Pnma-BN: Another Boron Nitride Polymorph with Interesting Physical Properties
| Autor: | Zheng Han, Xinhai Yu, Yi Tian, Dayun Wang, Zhenyang Ma, Xuhong Liu |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Materials science
Band gap General Chemical Engineering 02 engineering and technology mechanical properties 010402 general chemistry 01 natural sciences Article lcsh:Chemistry Shear modulus chemistry.chemical_compound General Materials Science Anisotropy Electronic band structure anisotropic properties BN polymorph electronic properties Condensed matter physics 021001 nanoscience & nanotechnology 0104 chemical sciences Crystallography lcsh:QD1-999 chemistry Boron nitride CASTEP Direct and indirect band gaps Local-density approximation 0210 nano-technology |
| Zdroj: | Nanomaterials, Vol 7, Iss 1, p 3 (2016) Nanomaterials; Volume 7; Issue 1; Pages: 3 Nanomaterials |
| ISSN: | 2079-4991 |
| DOI: | 10.3390/nano7010003 |
| Popis: | Structural, mechanical, electronic properties, and stability of boron nitride (BN) in Pnma structure were studied using first-principles calculations by Cambridge Serial Total Energy Package (CASTEP) plane-wave code, and the calculations were performed with the local density approximation and generalized gradient approximation in the form of Perdew–Burke–Ernzerhof. This BN, called Pnma-BN, contains four boron atoms and four nitrogen atoms buckled through sp3-hybridized bonds in an orthorhombic symmetry unit cell with Space group of Pnma. Pnma-BN is energetically stable, mechanically stable, and dynamically stable at ambient pressure and high pressure. The calculated Pugh ratio and Poisson’s ratio revealed that Pnma-BN is brittle, and Pnma-BN is found to turn brittle to ductile (~94 GPa) in this pressure range. It shows a higher mechanical anisotropy in Poisson’s ratio, shear modulus, Young’s modulus, and the universal elastic anisotropy index AU. Band structure calculations indicate that Pnma-BN is an insulator with indirect band gap of 7.18 eV. The most extraordinary thing is that the band gap increases first and then decreases with the increase of pressure from 0 to 60 GPa, and from 60 to 100 GPa, the band gap increases first and then decreases again. |
| Databáze: | OpenAIRE |
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