Structural, electronic properties and mechanical anisotropy of Amm2-carbon are investigated utilizing tlrst-principles calculations by Oambridge Serial Total Energy Package (CASTEP) code. The work is performed with ...Structural, electronic properties and mechanical anisotropy of Amm2-carbon are investigated utilizing tlrst-principles calculations by Oambridge Serial Total Energy Package (CASTEP) code. The work is performed with the generalized gradient approximation in the form of Perdew Burke-Ernzerhof (PBE), PBEsol, Wu and Cohen (WC) and local density approximation in the form of Ceperley and Alder data as parameterized by Perdew and Zunger (CA-PZ). The mechanical anisotropy eMculations show that Amm2-carbon exhibit large anisotropy in elastic moduli, such as Poisson's ratio, shear modulus and Young's modulus, and other anisotropy factors, such as the shear anisotropic factor and the universal anisotropic index AU. It is interestingly that the anisotropy in shear modulus and Young's modulus, universal anisotropic index and the shear anisotropie factor all increases with increasing pressure, but the anisotropy in Poisson's ratio decreases. The band structure calculations reveal that Amm2-carbon is a direct-band-gap semiconductor at ambient pressure, but with the pressure increasing, it becomes an indirect-band-gap semiconductor.展开更多
The mechanical anisotropy,structural properties,electronic band structures and thermal properties of C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)are detailed and investigated in this work.The novel silicon nitride phase Si2N2...The mechanical anisotropy,structural properties,electronic band structures and thermal properties of C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)are detailed and investigated in this work.The novel silicon nitride phase Si2N2(SiH2)and germanium nitride phase Ge2N2(GeH2)in the Cmc21 structure are proposed in this work.The novel proposed Si2N2(SiH2)and Ge2N2(GeH2)are both mechanically and dynamically stable.The electronic band calculation of the HSE06 hybrid functional shows that C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)are all wide band gap semiconductor materials,and C2N2(CH2)and Si2N2(SiH2)are direct band gap semiconductor materials,while Ge2N2(GeH2)is a quasi-direct band gap semiconductor material,the band gap of C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)are 5.634 eV,3.013 eV,and2.377 eV,respectively.The three-dimensional and plane distributions of Young’s modulus,shear modulus and Poisson’s ratio of C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)show that these materials have different degrees of mechanical anisotropy.The order of Young’s modulus of Si2N2(SiH2)and Ge2N2(GeH2)in different directions is different from that of C2N2(CH2).When the tensile axis is in a particular direction,the order of the Young’s modulus of Si2N2(SiH2):E[110]<E[120]<E[111]<E[101]<E[010]=E[100]<E[011]<E[001],and the order of the Young’s modulus of Ge2N2(GeH2):E[110]<E[111]<E[101]<E[120]<E[100]<E[010]<E[011]<E[001].展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.61564005
文摘Structural, electronic properties and mechanical anisotropy of Amm2-carbon are investigated utilizing tlrst-principles calculations by Oambridge Serial Total Energy Package (CASTEP) code. The work is performed with the generalized gradient approximation in the form of Perdew Burke-Ernzerhof (PBE), PBEsol, Wu and Cohen (WC) and local density approximation in the form of Ceperley and Alder data as parameterized by Perdew and Zunger (CA-PZ). The mechanical anisotropy eMculations show that Amm2-carbon exhibit large anisotropy in elastic moduli, such as Poisson's ratio, shear modulus and Young's modulus, and other anisotropy factors, such as the shear anisotropic factor and the universal anisotropic index AU. It is interestingly that the anisotropy in shear modulus and Young's modulus, universal anisotropic index and the shear anisotropie factor all increases with increasing pressure, but the anisotropy in Poisson's ratio decreases. The band structure calculations reveal that Amm2-carbon is a direct-band-gap semiconductor at ambient pressure, but with the pressure increasing, it becomes an indirect-band-gap semiconductor.
基金Project supported by the National Natural Science Foundation of China(grant numbers 61864004 and 61564005)。
文摘The mechanical anisotropy,structural properties,electronic band structures and thermal properties of C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)are detailed and investigated in this work.The novel silicon nitride phase Si2N2(SiH2)and germanium nitride phase Ge2N2(GeH2)in the Cmc21 structure are proposed in this work.The novel proposed Si2N2(SiH2)and Ge2N2(GeH2)are both mechanically and dynamically stable.The electronic band calculation of the HSE06 hybrid functional shows that C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)are all wide band gap semiconductor materials,and C2N2(CH2)and Si2N2(SiH2)are direct band gap semiconductor materials,while Ge2N2(GeH2)is a quasi-direct band gap semiconductor material,the band gap of C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)are 5.634 eV,3.013 eV,and2.377 eV,respectively.The three-dimensional and plane distributions of Young’s modulus,shear modulus and Poisson’s ratio of C2N2(CH2),Si2N2(SiH2)and Ge2N2(GeH2)show that these materials have different degrees of mechanical anisotropy.The order of Young’s modulus of Si2N2(SiH2)and Ge2N2(GeH2)in different directions is different from that of C2N2(CH2).When the tensile axis is in a particular direction,the order of the Young’s modulus of Si2N2(SiH2):E[110]<E[120]<E[111]<E[101]<E[010]=E[100]<E[011]<E[001],and the order of the Young’s modulus of Ge2N2(GeH2):E[110]<E[111]<E[101]<E[120]<E[100]<E[010]<E[011]<E[001].