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Materials 2018, 11(1), 80; https://doi.org/10.3390/ma11010080

Control of the Size of Silver Nanoparticles and Release of Silver in Heat Treated SiO2-Ag Composite Powders

1
Department of Chemistry and Materials Science, Aalto University School of Chemical Engineering, P.O. Box 16100, 00076 AALTO, 02150 Espoo, Finland
2
Rockley Photonics Oy, Tietotie 3, Micronova, 02150 Espoo, Finland
3
Department of Bioprocesses and Biosystems, Aalto University School of Chemical Engineering, P.O. Box 16300, 00076 AALTO, 02150 Espoo, Finland
*
Author to whom correspondence should be addressed.
Received: 21 November 2017 / Revised: 22 December 2017 / Accepted: 2 January 2018 / Published: 5 January 2018
(This article belongs to the Section Advanced Composites)
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Abstract

The growth of silver nanoparticles, the activation energy for silver particle growth, and the release of silver species in heat treated SiO 2 -Ag composite powders are investigated. The silver particle growth is controlled by heat treatment for 75 min of the as-synthesized SiO 2 -Ag composite powder at 300–800 °C. During heat treatment the mean size of the Ag particles increases from 10 nm up to 61 nm with increasing temperature, however, the particle size distribution widens and the mean size increases with increasing heat treatment temperature. Based on X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) studies, silver particles are crystalline and in a metallic state after annealing in all SiO 2 -Ag composite powders. The growth of Ag particles is suggested to take place via diffusion and Ostwald ripening. The activation energy for particle growth was determined as 0.14 eV. The dissolution of silver in aqueous solutions from the SiO 2 -Ag composites heat treated, at 300 °C, 600 °C, and 700 °C, was investigated by varying pH and temperature. The dissolution was reduced in all conditions with increasing silver particle size, i.e., when the total surface area of Ag particles is reduced. It is suggested that the dissolution of silver from the composite powders can conveniently be adjusted by controlling the Ag particle size by the heat treatment of the composite powder. View Full-Text
Keywords: silver; silica; controlled release; particle growth; nanoparticles; nanocomposite silver; silica; controlled release; particle growth; nanoparticles; nanocomposite
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Granbohm, H.; Larismaa, J.; Ali, S.; Johansson, L.-S.; Hannula, S.-P. Control of the Size of Silver Nanoparticles and Release of Silver in Heat Treated SiO2-Ag Composite Powders. Materials 2018, 11, 80.

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