Stability of elongated and compact types of structures in SiO2 nanoparticles

作者：Song JY; Choi M^*

来源：Physical Review B, 2002, 65(24): 241302.

DOI：10.1103/PhysRevB.65.241302

The stability of elongated and compact types of structure in SiO2 nanoparticles was studied using plane-wave density-functional theory. Calculations were carried out on small SiO2 nanoparticles with 12-46 molecules. It is found that elongated structures are favored for particles consisting of less than 38 molecules of SiO2. In contrast, nanoparticles containing more than 38 molecules favor the compact (spherical) structures. This indicates that the structural transition from elongated to compact structures occurs at a size of around 38 molecules. Several low-energy isomers of elongated types of structure for different sizes of SiO2 nanoparticles have been characterized. The nanoparticles are found to consist of various types of silica rings (four-, five-, and/or six-membered rings), similar to vitreous silica in bulk. The elongated structures consist of rather regular and symmetric silica rings, while the compact structures consist of considerably distorted silica rings. In particular, the elongated structures consisting of five-membered rings with the top and bottom layers being connected in the form of four-membered rings are relatively stable, leading to very regular and symmetric structures. The elongated types of structures might be proposed for the atomic structures of silica nanowires.

• 出版日期2002-6-15