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Titolo:
SMALL-ANGLE NEUTRON-SCATTERING OF AEROGELS - SIMULATIONS AND EXPERIMENTS
Autore:
HASMY A; FORET M; ANGLARET E; PELOUS J; VACHER R; JULLIEN R;
Indirizzi:
UNIV MONTPELLIER 2,SCI MAT VITREUX LAB,CNRS,UA 1119,PL EUGENE BATAILLON F-34095 MONTPELLIER 5 FRANCE
Titolo Testata:
Journal of non-crystalline solids
, volume: 186, anno: 1995,
pagine: 118 - 130
SICI:
0022-3093(1995)186:<118:SNOA-S>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
CLUSTER-CLUSTER AGGREGATION; DIFFUSION-LIMITED AGGREGATION; SILICA AEROGELS; 3 DIMENSIONS; MODEL; SIZE; SPHERES; GELS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
36
Recensione:
Indirizzi per estratti:
Citazione:
A. Hasmy et al., "SMALL-ANGLE NEUTRON-SCATTERING OF AEROGELS - SIMULATIONS AND EXPERIMENTS", Journal of non-crystalline solids, 186, 1995, pp. 118-130

Abstract

Numerical simulation of silica aerogels was performed using diffusion-limited cluster-cluster aggregation of spheres inside a cubic box (with periodic boundary conditions). The volume fraction, c, was taken tobe sufficiently; large to obtain a gel structure at the end of the process. In the case of monodisperse spheres, the wave-vector-dependent scattered intensity, I(q), was calculated from the product of the formfactor, P(q). of a sphere by the structure factor, S(q). which is related to the Fourier transform of g(r)-1, where g(r) is the pair correlation function betwteen spheres centers. The structure factor, S(q), exhibits large-q damped oscillations characteristics of the short-range(intra-aggregate) correlations between spheres. These oscillations influence the I(q) curve in the region of q between the fractal regime and the Porod regime and quantitative comparisons were made with experiments on colloidal aerogels. At small values of q. S(q) goes through amaximum characteristic of large-range (inter-aggregate) correlations. Quantitative fits of the maximum in the experimental I(q) curves of base-catalyzed aerogels are presented. In the case of polydisperse spheres, I(q) was directly calculated from a single aggregate simulation. increasing polydispersity shifts the location of the cross-over between the fractal and Pored regimes towards lower values of q.

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Documento generato il 02/12/20 alle ore 18:32:37