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Reconstruction of pristine and hydrolyzed quartz surfaces.

Authors
Murashov-VV
Source
J Phys Chem B Condens Mater Surf Interfaces Biophys 2005 Mar; 109(9):4144-4151
NIOSHTIC No.
20026557
Abstract
Reconstruction of the most common pristine and hydrolyzed surfaces of quartz was investigated with periodic density functional theory calculations. Surface energies of reconstructed pristine faces, pertinent to quartz growth morphologies in melts, are found to range from 0.071 eV/A2 for the (101) surface to 0.139 eV/A2 for the (001) surface, and they increase as (101) < (102) < (112) < [(100), (111)] < (110) < (001). Four types of reconstruction reactions are observed: (1) formation of two-membered rings from vicinal silyl and siloxy sites, (2) formation of a pair of tricoordinated/unicoordinated oxygen atoms, (3) formation of three-membered rings, and (4) transformation of silanone sites into siloxane sites. The main features of reconstructed pristine quartz surfaces are two-membered rings formed from bridged siloxy and silyl sites on all investigated surfaces, a stable site complex with geminal positively charged tricoordinated and negatively charged unicoordinated oxygen atoms revealed on the (112) surface, and charged nonbridged siloxy/silyl sites, which are more stable than radical siloxy/silyl sites. Hydrolyzed surface energies range from -0.010 eV/A2 for the (001) surface to 0.002 eV/A2 for the (101) surface and increase as (001) < (110) < (102) < (111) < (100) < (112) < (101). The hydrolyzed surface stability is found to depend strongly on inter-site silanol hydrogen bonding. Observed networks of hydrogen bonds are important for interactions between silica surfaces and biomolecules in an aqueous environment.
Keywords
Quartz-dust; Surface-properties; Morphology; Silica-dusts; Silicates; Aqueous-solutions; Environmental-factors
CODEN
JPCBFK
CAS No.
14808-60-7
Publication Date
20050310
Document Type
Journal Article
Fiscal Year
2005
NTIS Accession No.
NTIS Price
Issue of Publication
9
ISSN
1520-6106
NIOSH Division
HELD
Source Name
The Journal of Physical Chemistry, Part B. Condensed Matter, Materials, Surfaces, Interfaces & Biophysical
State
WV
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