CW and Pulsed EPR Study of Silver Nanoparticles in a SiO2 Matrix

Metallic silver nanoparticles were prepared by the sol-gel method in an SiO2 matrix. The process includes complexation of silicon alkoxides with metal salts, hydrolysis, polycondensation, formation of powder, and subsequent thermal treatment first in oxidizing and second in reducing atmospheres. The...

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Bibliographic Details
Published in:Journal of sol-gel science and technology 1998-01, Vol.13 (1-3), p.503-508
Main Authors: Mitrikas, G, Deligiannakis, Y, Trapalis, C C, Boukos, N, Kordas, G
Format: Article
Language:English
Subjects:
Alkoxides
Electron paramagnetic resonance
Heat treatment
Magnetic properties
Metal particles
Nanoparticles
Oxidation
Reducing atmospheres
Relaxation time
Silicon dioxide
Silver
Sol-gel processes
Spin-lattice relaxation
Temperature dependence
Transmission electron microscopy
X-ray diffraction
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Summary:Metallic silver nanoparticles were prepared by the sol-gel method in an SiO2 matrix. The process includes complexation of silicon alkoxides with metal salts, hydrolysis, polycondensation, formation of powder, and subsequent thermal treatment first in oxidizing and second in reducing atmospheres. The sizes of metallic particles were determined both by X-ray diffraction and transmission electron microscopy. These measurements revealed sizes of metallic particles between 1 and 20 nm, depending upon processing conditions. The magnetic properties were investigated using electron paramagnetic resonance spectroscopy in the temperature range between 4 and 300 K. The spin-lattice relaxation time T1 was measured by pulsed EPR. The temperature dependence of T1 is described by the relation 1/T1 ∝ Tn, where 0.4 < n < 1. This behavior is unusual and different from any well-known relaxation processes such as Raman, Direct or the Orbach-Aminov.
ISSN:0928-0707
1573-4846
DOI:10.1023/A:1008654102264