Ion Segregation and Deliquescence of Alkali Halide Nanocrystals on SiO2

Journal Article · Tue Aug 11 04:00:00 EDT 2009 · Journal of Physical Chemistry A

DOI:https://doi.org/10.1021/jp904151m· OSTI ID:973612

Arima, Kenta; Jiang, Peng; Lin, Deng-Sung; Verdaguer, Albert; Salmeron, Miquel

The adsorption of water on alkali halide (KBr, KCl, KF, NaCl) nanocrystals on SiO{sub 2} 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.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Materials Sciences Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 973612
• Report Number(s): LBNL-2618E
• Journal Information: Journal of Physical Chemistry A, Journal Name: Journal of Physical Chemistry A Journal Issue: 35 Vol. 113
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADSORPTION
ANIONS
DIFFUSION
ELECTROSTATICS
HALIDES
HUMIDITY
MICROSCOPY
PERMITTIVITY
POLARIZATION
RIPENING
SATURATION
SEGREGATION
SURFACE POTENTIAL
WATER