e-Journal of Surface Science and Nanotechnology
Online ISSN : 1348-0391
Conference -ISSS-8-
Electrical Conductivity at Surfaces of Silica Nanoparticles with Adsorbed Water at Various Relative Humidities
Ryosuke UmezawaMakoto KatsuraSatoru Nakashima
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2018 Volume 16 Pages 376-381

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Abstract

Electrical conductivity of silica nanoparticles deposited on electrodes from colloidal suspension were measured under controlled relative humidity (RH). The electrical conductivity values at 1 kHz increased with increasing RH. Amounts of water adsorbed on silica nanoparticles were measured by quartz crystal microbalance (QCM) and they also increased with increasing RH. An empirical power law relation was observed between the reported surface conductivity and RH data for a silica glass. By applying this relation to the silica nanoparticles, the water film thicknesses are estimated to be from 0.08 nm to 0.23 nm. The corresponding specific surface area (SSA) becomes smaller (102 m2g1) than the reported value (215 m2g−1), indicating aggregation of the nanoparticles. In fact, aggregated rod-like structures were observed under electron and laser scanning microscopy. The electrical conduction of deposited silica nanoparticles under various RH can be understood by surface conduction in thin water films adsorbed on the nanoparticles. [DOI: 10.1380/ejssnt.2018.376]

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