Theoretical Study of Two-Dimensional Silica Films
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- 作者：Vasilii I. Artyukhov ; Leonid A. Chernozatonskii
- 刊名：Journal of Physical Chemistry C
- 出版年：2010
- 出版时间：June 3, 2010
- 年：2010
- 卷：114
- 期：21
- 页码：9678-9684
- 全文大小：191K
- 年卷期：v.114,no.21(June 3, 2010)
- ISSN：1932-7455
文摘
Properties of hypothetical planar silica polymorphs are investigated. First, the general topological features of possible atomically thin two-dimensional silica nanostructures are analyzed. On the basis of this analysis, two fundamental structure types (termed tetragonal and trigonal) that represent the possible local topological arrangements are chosen for a plane-wave density functional theory study. Whereas the trigonal motif is energetically favorable for the formation of monomolecular films and spherical fullerene-like nanoclusters, the tetragonal structure is more suitable for single-walled nanotubes of silica. The strain energy of trigonal films results entirely from two-membered rings, allowing us to estimate the energy cost of two-ring formation (1.30 eV), excluding any additional strain contribution from the environment. All structures possess strong dielectric properties with a band gap only slightly smaller than that in α-quartz and other bulk forms of silica. Reorganization of the band structure is seen; it is especially pronounced when two-membered rings are present in the system. The results of our calculations and other studies are brought together in order to grasp a better view on the place that these nanostructures occupy within the diversity of silica forms, with a conclusion that they lie well within the experimentally accessible range of total energies. From this, we infer that a segment of the (6,0) nanotube is the “ground-state” configuration for (SiO2)N clusters with N ≥ 36.