Particle Transport in Nanoscale Colloidal Suspensions

Improvements in particulate coatings for printable paper require understanding mechanisms of colloidal interactions in paper coating suspensions. One way to deduce colloidal interactions is to mage particle spacings and orientations at high resolution with cryo-SEM. Recent improvements in cryo-SEM technique have increased resolution enough to image particles in coating paints,vhich are sometimes smaller than 100 nm. In this report, a metal-coating chamber is described for preparation of colloidal suspensions for cryo-SEM at resolution down to 20 nm. It was found that etching is not necessary to achieve this resolution.A 120 K cryo-SEM sample will remain in an SEM for hours without noticeable condensation of imorphous ice. This is due to the high vapor pressure of vapor-condensed amorphous ice, measured by Kouchi. However, clean vacuum is required to coat samples with the thinnest possible continuous metal films which are required for high magnification SEM. Vapor contaminants, especially hrydrocarbons, are known to interfere with thin-film nucleation and growth so that more metal is needed to form continuous films, and resolution is decreased. That is why the metal-coating chamber in fig. 1 is designed for the cleanest possible vacuum. Feedthroughs for the manipulator md the shutter, which are operated during metal coating, are sealed with leak-proof stainless-steel Dellows. The transfer rod slides through a baseplate feedthrough that is double o-ring sealed.

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Chapter 5 Plinian eruption columns: particle transport and fallout

Developments in Volcanology ◽

10.1016/s1871-644x(01)80006-1 ◽

1998 ◽

Vol 4 ◽

pp. 139-172 ◽

Cited By ~ 1

Author(s):

M ROSI

Keyword(s):

Particle Transport ◽

Plinian Eruption

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Computing Numerically-Optimal Bounding Boxes for Constructive Solid Geometry (CSG) Components in Monte Carlo Particle Transport Calculations

SNA + MC 2013 - Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo ◽

10.1051/snamc/201402506 ◽

2014 ◽

Author(s):

David L. Millman ◽

David P. Griesheimer ◽

Brian R. Nease ◽

Jack Snoeyink

Keyword(s):

Monte Carlo ◽

Particle Transport ◽

Constructive Solid Geometry ◽

Solid Geometry ◽

Bounding Boxes

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Growth Kinetics of Quantum Size ZnO Particles

MRS Proceedings ◽

10.1557/proc-536-347 ◽

1998 ◽

Vol 536 ◽

Author(s):

E. M. Wong ◽

J. E. Bonevich ◽

P. C. Searson

Keyword(s):

Growth Kinetics ◽

Ostwald Ripening ◽

Chemical Potential ◽

Colloidal Suspensions ◽

Green Emission ◽

Blue Shift ◽

Constant Current ◽

Mass Model ◽

Zno Particles ◽

Kinetics Of

AbstractColloidal chemistry techniques were used to synthesize ZnO particles in the nanometer size regime. The particle aging kinetics were determined by monitoring the optical band edge absorption and using the effective mass model to approximate the particle size as a function of time. We show that the growth kinetics of the ZnO particles follow the Lifshitz, Slyozov, Wagner theory for Ostwald ripening. In this model, the higher curvature and hence chemical potential of smaller particles provides a driving force for dissolution. The larger particles continue to grow by diffusion limited transport of species dissolved in solution. Thin films were fabricated by constant current electrophoretic deposition (EPD) of the ZnO quantum particles from these colloidal suspensions. All the films exhibited a blue shift relative to the characteristic green emission associated with bulk ZnO. The optical characteristics of the particles in the colloidal suspensions were found to translate to the films.

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