Pnma-BN: Another boron nitride polymorph with interesting physical properties

Zhenyang Ma, Zheng Han, Xuhong Liu, Xinhai Yu, Dayun Wang, Yi Tian

    Research output: Contribution to journalArticlepeer-review

    35 Citations (Scopus)


    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.

    Original languageEnglish
    Article number3
    Issue number1
    Publication statusPublished - 2017 Jan 1


    • Anisotropic properties
    • BN polymorph
    • Electronic properties
    • Mechanical properties

    ASJC Scopus subject areas

    • Chemical Engineering(all)
    • Materials Science(all)


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