AB-INITIO CALCULATION OF THE MECHANICAL STRENGTH OF THE SI-O-SI BOND

Citation
Vs. Yushchenko et al., AB-INITIO CALCULATION OF THE MECHANICAL STRENGTH OF THE SI-O-SI BOND, Journal of Materials Science, 29(11), 1994, pp. 3038-3042
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science
ISSN journal
0022-2461
Volume
29
Issue
11
Year of publication
1994
Pages
3038 - 3042
Database
ISI
SICI code
0022-2461(1994)29:11<3038:ACOTMS>2.0.ZU;2-2
Abstract
The theoretical mechanical strength of the Si-O-Si bond has been evalu ated by means of ab initio RHF/3-21 G calculations on the Si2O7H6 Mol ecule simulating the structure of the alpha-cristobalite crystal. Defo rmation was applied by increasing the distance between the silicon ato ms from equilibrium up to the distance of maximum force. The position of the bridging oxygen has been optimized at each step of deformation. The interatomic force, the total energy, atom charges and overlap pop ulation have been calculated as functions of the Si-Si separation. The strength of the structure appears to be equal to 1.1 mdyn, i.e the th eoretical strength of the crystal for fracture along the [011] plane i s equal to 64 GPa. The model used has been found to overestimate stron gly the rigidity of the Si-O-Si angle and therefore the elasticity of silica. Nevertheless, the value of the ideal strength (that is determi ned by the strength of the Si-O bond) may be considered as a reasonabl e approximation.