Novel silicon allotropes: Stability, mechanical, and electronic properties

Fan, Qingyang; Chai, Changchun; Wei, Qun; Yan, Haiyan; Zhao, Yingbo; Yang, Yintang; Yu, Xinhai; Liu, Yang; Ming, Xing; Zhang, Junqin; Yao, Ronghui

doi:10.1063/1.4935549

Cited by 51 publications

(46 citation statements)

References 27 publications

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“…Four additional semiconducting low-energy silicon phases were reported by Fan et al: Amm2 (oA20), C2/m (mC16), C2/m (mC20), and I 4 (tI28). 97 All four structures were reported previously for carbon. 98 The calculations at the GGA-based DFT level revealed that the Amm2 silicon phase has a quasidirect band gap of 0.742 eV and a formation energy of 0.109 eV/atom.…”

Section: B Many New Forms Of Silicon Are Plausiblementioning

confidence: 99%

Pathways to exotic metastable silicon allotropes

Haberl

Strobel

Bradby

2016

Applied Physics Reviews

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The Group 14 element silicon possesses a complex free-energy landscape with many (local) minima, allowing for the formation of a variety of unusual structures, some of which may be stabilized at ambient conditions. Such exotic silicon allotropes represent a significant opportunity to address the ever-increasing demand for novel materials with tailored functionality since these exotic forms are expected to exhibit superlative properties including optimized band gaps for solar power conversion. The application of pressure is a well-recognized and uniquely powerful method to access exotic states of silicon since it promotes large changes to atomic bonding. Conventional high-pressure syntheses, however, lack the capability to access many of these local minima and only four forms of exotic silicon allotropes have been recovered over the last 50 years. However, more recently, significant advances in high pressure methodologies and the use of novel precursor materials have yielded at least three more recoverable exotic Si structures. This review aims to give an overview of these innovative methods of high-pressure application and precursor selection and the recent discoveries of new Si allotropes. The background context of the conventional pressure methods and multitude of predicted new phases are also provided. This review also offers a perspective for possible access to many further exotic functional allotropes not only of silicon but also of other materials, in a technologically feasible manner.

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Section: B Many New Forms Of Silicon Are Plausiblementioning

confidence: 99%

Pathways to exotic metastable silicon allotropes

Haberl

Strobel

Bradby

2016

Applied Physics Reviews

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“…The bulk modulus of P 2/ m -Si is slightly smaller than that of diamond silicon. The shear modulus of P 2/ m -Si is also slightly smaller than that of diamond silicon but is the greatest among those of P 2/ m -Si, C 2/ m -16 Si, C 2/ m -20 Si, and I -4 Si [10]. The hardness of a material can determine the plastic and elastic properties to some extent and can be predicted by following formula [34]:

H_{V} = 2 {{false(normalk}^{2} normalG false)}^{0.585} - 3

…”

Section: Resultsmentioning

confidence: 99%

A Novel Silicon Allotrope in the Monoclinic Phase

et al. 2017

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This paper describes a new silicon allotrope in the P2/m space group found by first-principles calculations using the Cambridge Serial Total Energy Package (CASTEP) plane-wave code. The examined P2/m-Si belongs to the monoclinic crystal system. P2/m-Si is an indirect band-gap semiconductor with a band gap of 1.51 eV, as determined using the HSE06 hybrid functional. The elastic constants, phonon spectra and enthalpy indicate that P2/m-Si is mechanically, dynamically, and thermodynamically stable. P2/m-Si is a low-density (2.19 g/cm3) silicon allotrope. The value of B/G is less than 1.75, which indicates that the new allotrope is brittle. It is shown that the difference in the elastic anisotropy along different orientations is greater than that in other phases. Finally, to understand the thermodynamic properties of P2/m-Si, the thermal expansion coefficient α, the Debye temperature ΘD, and the heat capacities CP and CV are also investigated in detail.

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“…Moreover, the elastic anisotropic of the material could be shown by the percentage of elastic anisotropy for the bulk modulus A B , the percentage of elastic anisotropy for the shear modulus A G , and the universal anisotropic index A U : A U = 5 G V / G R + B V / B R − 6, A B = ( B V − B R )/( B V + B R ), and A G = ( G V − G R )/( G V + G R ) [ 65 ]. The calculated values of A B , A G and A U of t -Si x Ge 3− x N 4 , c -Si x Ge 3− x N 4 , and m -Si x Ge 3− x N 4 ( x = 0, 1, 2, 3) alloys are all listed in Table 3 .…”

Section: Resultsmentioning

confidence: 99%

Structural, Electronic, and Thermodynamic Properties of Tetragonal t-SixGe3−xN4

et al. 2018

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The structural, mechanical, anisotropic, electronic, and thermal properties of t-Si3N4, t-Si2GeN4, t-SiGe2N4, and t-Ge3N4 in the tetragonal phase are systematically investigated in the present work. The mechanical stability is proved by the elastic constants of t-Si3N4, t-Si2GeN4, t-SiGe2N4, and t-Ge3N4. Moreover, they all demonstrate brittleness, because B/G < 1.75, and v < 0.26. The elastic anisotropy of t-Si3N4, t-Si2GeN4, t-SiGe2N4, and t-Ge3N4 is characterized by Poisson’s ratio, Young’s modulus, the percentage of elastic anisotropy for bulk modulus AB, the percentage of elastic anisotropy for shear modulus AG, and the universal anisotropic index AU. The electronic structures of t-Si3N4, t-Si2GeN4, t-SiGe2N4, and t-Ge3N4 are all wide band gap semiconductor materials, with band gaps of 4.26 eV, 3.94 eV, 3.83 eV, and 3.25 eV, respectively, when using the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional. Moreover, t-Ge3N4 is a quasi-direct gap semiconductor material. The thermodynamic properties of t-Si3N4, t-Si2GeN4, t-SiGe2N4, and t-Ge3N4 are investigated utilizing the quasi-harmonic Debye model. The effects of temperature and pressure on the thermal expansion coefficient, heat capacity, Debye temperature, and Grüneisen parameters are discussed in detail.

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Novel silicon allotropes: Stability, mechanical, and electronic properties

Cited by 51 publications

References 27 publications

Pathways to exotic metastable silicon allotropes

Pathways to exotic metastable silicon allotropes

A Novel Silicon Allotrope in the Monoclinic Phase

Structural, Electronic, and Thermodynamic Properties of Tetragonal t-SixGe3−xN4

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