Pnma-BN: Another Boron Nitride Polymorph with Interesting Physical Properties

Abstract

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.

III‐Nitride Polymorphs: XN (X=Al, Ga, In) in the Pnma Phase

“…The three-dimensionalc rystal structure is shown in Figure 2(a), and the crystal structures of Pnma-XN (X = Al, Ga, In) in the Pnma phase along the [1 00]d irection and the 2 2 2s upercell structure of Pnma-XN (X = Al, Ga, In) are shown in Figure 2(b) and (c), respectively.T he crystal structures of Pnma-XN (X = Al, Ga, In) are the same as Pnma-BN. [18] The three-dimensional crystal structures of Pnma-XN consist of sp 3 -bonded rings, including the four-, six-, and eight-membered X-N (X = Al, Ga, In) rings. Figure 2 The calculated lattice parameters of XN (X = Al, Ga, In) in the Pnma phase and F4 3m phase are listed in Ta ble 1.…”

“…Allb and structures of XN (X = Al, Ga, In) in the Pnma phase are obtained under the action of the HSE06 hybrid functional. [27] The Pnma-BN [18] is an insulator with ab and gap of 7.18 eV.F rom Figure 8, XN (X = Al, Ga, In) in the Pnma phase are all direct semiconductor materials with band gaps of 4.76 eV,2 .80 eV,a nd 0.66 eV,r espectively,h owever,i ti sn oted that the band gap of Pnma-GaN is 2.80 eV,m aking it ap otential binary semiconductor material forv iolet-light diodes, which saves the trouble of adulteration compared with the previous material. This is due to the fact that making infrared detectors and ultraviolet detectors mainly uses ternary semiconductor alloys such as AlGaAs, GaAsP,A lGaN, or AlGaInP quaternary semiconductor alloys.…”

“…Recently,m ore and more researchers have begun to study the polymorphs of the XN compounds (X = Al, Ga, In). [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Yang et al [6] investigated the structural, elastic,thermodynamic, electronic, and opticalp roperties of four novel compounds: Pmn2 1 -AlN, Pbam-AlN, Pbca-AlN, and Cmcm-AlN. They found that the AlN in the Cmcm phase has ab etter plasticity and also has al arger elastic anisotropyi nY oung's modulus than Pmn2 1 -AlN, Pbam-AlN, and Pbca-AlN.…”

Physical Properties of XN (X = B, Al, Ga, In) in the Pm−3n phase: First-Principles Calculations

“…Therefore, in the application of semiconductors, compatibility means are often used to make the two compatible and utilize their respective advantages. Because of this, more and more attention has been paid to research on new structures and the physical properties of the compounds [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

“…Lately, a growing number of studies have been conducted in the field of novel semiconductor materials, such as III-V nitride compound [1][2][3][4][5][6][7][8][9], other III-V compound materials [13][14][15][16][17][18][19][20], carbon-based [14][15][16][17][18][19][20][21], and silicon-based [22][23][24][25][26][27][28]. The structural properties, electronic properties, mechanical attributes, and stableness of the BN polymorph in the Pnma structure were investigated, utilizing first-principles calculations by the Cambridge Serial Total Energy Package (CASTEP) plane-wave code, which was studied by Ma et al [1]. They also discovered that Pnma-BN has larger band gap (7.18 eV) than other BN polymorphs, and it has an indirect band gap with the HSE06 function [29].…”