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The structure of vitreous silica
Author(s) -
Mozzi R. L.,
Warren B. E.
Publication year - 1969
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889869006868
Subject(s) - interpretation (philosophy) , silicon , bond length , intensity (physics) , atom (system on chip) , materials science , distribution (mathematics) , excitation , orientation (vector space) , molecular physics , oxygen atom , atomic physics , crystallography , chemistry , optics , physics , mathematics , molecule , crystal structure , geometry , mathematical analysis , quantum mechanics , organic chemistry , computer science , metallurgy , programming language , embedded system
A new study of the structure of vitreous silica has been made under greatly improved conditions. Using Rh K α radiation with the method of fluorescence excitation, reliable intensity values were measured to 4π sinθ/λ = 20. The interpretation was in terms of pair functions, thereby eliminating the approximations in earlier work. Each silicon is tetrahedrally surrounded by 4 oxygen atoms, with a Si–O distance which is closely 1.62 Å. Each oxygen atom is bonded to 2 silicon atoms. The Si–O–Si bond angle α shows a distribution V (α) extending all the way from 120° to 180°, with a maximum at α = 144°. This wide variation in α is an important distinction between the vitreous and the crystalline forms of silica, and it furnishes an important criterion for any proposed model of vitreous silica. Good agreement with the measured pair function distribution curve was obtained by assuming a random orientation about the Si–O bond directions. The interpretation leads to the familiar random network model, but with the new results the model is more precise.