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The Nanostructures Of Amorphous Silicas

Published online by Cambridge University Press:  02 July 2020

Linn W. Hobbs
Affiliation:
Department of Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307
Xianglong Yuan
Affiliation:
Department of Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307
L. C. Qin
Affiliation:
Department of Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139-4307 present address: Fundamental Research Laboratory, NEC Corporation, Tsukuba, Ibaraki 305, Japan
Vinay Pulim
Affiliation:
Laboratory for Computer Science, Massachusetts Institute of Technology, Cambridge, MA02139-4307
Alexander Coventry
Affiliation:
Laboratory for Computer Science, Massachusetts Institute of Technology, Cambridge, MA02139-4307
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Silicon dioxide is an important catalyst material, a mainstay insulator in microelectronics, and a widely distributed terrestrial and marine skeletal mineral. Geologically, it is found in one of a large number of polymorphic crystalline states, but can also be rendered “amorphous” by rapid cooling from the melt through a glass transition, depositing from a vapor or from solution (in radiolaria skeletons), oxidizing silicon, or irradiating with electrons, ions or neutrons. While the structures of the crystalline polymorphs are well documented, the structure of even the exhaustively studied vitreous silica remains largely enigmatic. Diffraction provides average information about short-range order—which appears to comprise [SiO4] tetrahedral units in all but a high-pressure crystalline polymorph—but is relatively insensitive to alternative medium-range arrangements of these structural units. One sensitive, but little understood, indicator is the position and shape of the first sharp diffraction peak (FSDP).

Type
Sir John Meurig Thomas Symposium: Microscopy and Microanalysis in the Chemical Sciences
Copyright
Copyright © Microscopy Society of America

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References

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