TY - JOUR
T1 - Quantification of microstructures in stable and gelated suspensions from Cryo-SEM
AU - Wyss, H.M.
AU - Hütter, M.
AU - Müller, M.
AU - Meier, L.P.
AU - Gauckler, L.J.
PY - 2002
Y1 - 2002
N2 - It is shown that the microstructures of concentrated suspensionscan be analyzed in a quantitative way from cryo-SEM images ofhigh-pressure frozen samples, both in the electrostatically stabilizedand in the flocculated state. Suspensions of spherical silica particles(40 vol%) in an aqueous solution were used. The average particle radiuswas 525nmwith a polydispersity of below 7%. The suspensionswere high-pressure frozen, which resulted in a quenching of the configurationwithout apparent change in volume or crack formation.After fracturing the samples at liquid nitrogen temperature, thefracture surface was etched by controlled sublimation of the frozenaqueous phase, coated with 8 nm of platinum, and examined bystereo-cryo-SEM. The 3-dimensional positions of all the visible particles were determined from theSEMimages. Assuming an isotropicparticle configuration in the sample before cracking, it is possible toextract the 3-dimensional pair correlation function from the particlepositions on the fracture surface. A comparison to recent resultsfrom Brownian Dynamics simulations shows good agreement betweenour experiments and the simulations.
AB - It is shown that the microstructures of concentrated suspensionscan be analyzed in a quantitative way from cryo-SEM images ofhigh-pressure frozen samples, both in the electrostatically stabilizedand in the flocculated state. Suspensions of spherical silica particles(40 vol%) in an aqueous solution were used. The average particle radiuswas 525nmwith a polydispersity of below 7%. The suspensionswere high-pressure frozen, which resulted in a quenching of the configurationwithout apparent change in volume or crack formation.After fracturing the samples at liquid nitrogen temperature, thefracture surface was etched by controlled sublimation of the frozenaqueous phase, coated with 8 nm of platinum, and examined bystereo-cryo-SEM. The 3-dimensional positions of all the visible particles were determined from theSEMimages. Assuming an isotropicparticle configuration in the sample before cracking, it is possible toextract the 3-dimensional pair correlation function from the particlepositions on the fracture surface. A comparison to recent resultsfrom Brownian Dynamics simulations shows good agreement betweenour experiments and the simulations.
U2 - 10.1006/jcis.2001.8220
DO - 10.1006/jcis.2001.8220
M3 - Article
C2 - 16290538
VL - 248
SP - 340
EP - 346
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
SN - 0021-9797
IS - 2
ER -