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Internal Structure of Porous Silica: A Model System for Characterization by Nuclear Magnetic Resonance
Author(s) -
Bhattacharja Sankar,
D'Orazio F.,
Tarczon J. C.,
Halperin W. P.,
Gerhardt Rosario
Publication year - 1989
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1989.tb06043.x
Subject(s) - porosity , porosimetry , materials science , relaxation (psychology) , silicate , confined space , nuclear magnetic resonance , porous medium , diffusion , analytical chemistry (journal) , mineralogy , chemistry , composite material , chromatography , thermodynamics , organic chemistry , psychology , social psychology , physics
Nuclear magnetic resonance (NMR) relaxation methods have been used to investigate the internal structure of porous silica gelled from colloidal silica and potassium silicate mixtures. These materials possess a narrow pore size distribution with average pore diameter ranging from 470 to 2400 Å (47 to 240 nm) as determined from mercury intrusion porosimetry. NMR relaxation measurements were performed on deionized water impregnated into the pore space. These results determine the distribution of local surface‐to‐volume ratios and show that all of the silica samples are very uniform on a length scale greater than 5 μ. NMR relaxation measurements performed on silica samples partially filled with water provide a precise confirmation of the theoretical model upon which the NMR pore structure analysis is based. Measurements of the relaxation strength at the water—silica interface were found to depend systematically on the initial composition of the material. The self‐diffusion coefficient of water, saturated in the pore space, is reduced by 14% from its bulk value.