International Journal of
Physical Sciences

  • Abbreviation: Int. J. Phys. Sci.
  • Language: English
  • ISSN: 1992-1950
  • DOI: 10.5897/IJPS
  • Start Year: 2006
  • Published Articles: 2533

Full Length Research Paper

High pressure phase stability, elastic anisotropy and electronic properties of BC2N

Habanyama A.
  • Habanyama A.
  • Department of Physics, Copperbelt University, P. O. Box 21692, Jambo Drive, Riverside, Kitwe 10101, Zambia.
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Samukonga G.
  • Samukonga G.
  • Department of Physics, Copperbelt University, P. O. Box 21692, Jambo Drive, Riverside, Kitwe 10101, Zambia.
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Mumba N. K.
  • Mumba N. K.
  • Department of Physics, Copperbelt University, P. O. Box 21692, Jambo Drive, Riverside, Kitwe 10101, Zambia.
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  •  Received: 11 December 2020
  •  Accepted: 19 October 2021
  •  Published: 30 November 2021

Abstract

Crystal lattice structure searching by Particle Swarm Optimization (PSO) and first-principles structural optimization have been used to explore polymorphs of BC2N, possessing sp3 hybridization, under a varying applied hydrostatic pressure. Two low Gibbs free energy structures were identified: one with a primitive orthorhombic structure and Space Group, Pmm2, and the other with a primitive tetragonal structure and Space Group, P m2. Dynamical and mechanical stabilities of the Pmm2, orthorhombic BC2N (o-BC2N) structure were established using its phonon dispersions and elastic constants. The bulk modulus of this predicted BC2N phase was 377.15 GPa, which indicates a super-hard compound. The material is brittle with a B/G ratio of 0.911 and a low degree of elastic anisotropy with a Universal Elastic Anisotropy Index of only 0.774%. Calculations of the electronic band structure demonstrated that the material is a direct band gap semiconductor with a band gap of 1.731 eV at zero applied pressure. The band gap increases monotonically with increased applied pressure and saturates to a value of about 1.756 eV above 1500 kbars; the hydrostatic pressure coefficients associated with this process were determined. 

Key words: High pressure phase stability, elastic anisotropy, ultra-hard material.