Ion Segregation and Deliquescence of Alkali Halide Nanocrystals on SiO2 [electronic resource].

Published:: Berkeley, Calif. : Lawrence Berkeley National Laboratory, 2009.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Additional Creators:: Lawrence Berkeley National Laboratory and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

The adsorption of water on alkali halide (KBr, KCl, KF, NaCl) nanocrystals on SiO₂ and their deliquescence was investigated as a function of relative humidity (RH) from 8% to near saturation by scanning polarization force microscopy. At low humidity, water adsorption solvates ions at the surface of the crystals and increases their mobility. This results in a large increase in the dielectric constant, which is manifested in an increase in the electrostatic force and in an increase in the apparent height of the nanocrystals. Above 58% RH, the diffusion of ions leads to Ostwald ripening, where larger nanocrystals grow at the expense of the smaller ones. At the deliquescence point, droplets were formed. For KBr, KCl, and NaCl, the droplets exhibit a negative surface potential relative to the surrounding region, which is indicative of the preferential segregation of anions to the air/solution interface.

Report Numbers:

E 1.99:lbnl-2618e
lbnl-2618e

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Published through SciTech Connect.
08/11/2009.
"lbnl-2618e"
Journal of Physical Chemistry A 113 35 FT
Salmeron, Miquel; Jiang, Peng; Verdaguer, Albert; Arima, Kenta; Lin, Deng-Sung.
Materials Sciences Division

Funding Information:

DE-AC02-05CH11231

View MARC record | catkey: 14444897