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Unveiling the first post-graphene member of silicon nitrides: A novel 2D material
Computational Materials Science ( IF 3.3 ) Pub Date : 2020-07-01 , DOI: 10.1016/j.commatsci.2020.109693
Ashkan Shekaari , Mahmoud Jafari

Abstract We have theoretically predicted a new two-dimensional allotrope of the silicon nitrides family, being found during our effort to construct a nanosheet from the unit cell of hexagonal β -Si3N4. Electronic structure calculations at the DFT-PBE level of theory have revealed that this new material is an insulator with a band gap of about 4 eV. Finite-temperature density functional molecular dynamics simulations applied at the unit-cell level have also verified that the new compound is thermodynamically more stable than the layered form of hexagonal β -Si3N4 due to having both stronger Si–N bonds and a more compact crystal structure. Furthermore, phonon dispersion calculations have tested and proved the dynamic stability of the new monolayer to a great accuracy with accordingly no soft modes being observed. Results obtained within the quasi-harmonic approximation also demonstrate that our predicted material is indeed a Debye solid with a low-temperature specific heat proportional to T 2 as a consequence of its two-dimensional nature, possessing a Debye temperature of about 860 K considerably higher than those of α , β , and γ phases of Si3N4.

中文翻译:

揭示氮化硅的第一个后石墨烯成员:一种新型二维材料

摘要 我们从理论上预测了氮化硅家族的一种新的二维同素异形体,它是在我们努力从六方 β -Si3N4 的晶胞构建纳米片的过程中发现的。DFT-PBE 理论水平的电子结构计算表明,这种新材料是一种带隙约为 4 eV 的绝缘体。应用于晶胞水平的有限温度密度泛函分子动力学模拟也证实,由于具有更强的 Si-N 键和更紧凑的晶体结构,新化合物在热力学上比六方 β-Si3N4 的层状形式更稳定. 此外,声子色散计算已经非常准确地测试并证明了新单层的动态稳定性,因此没有观察到软模式。
更新日期:2020-07-01
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