Environmental Engineering Reference
In-Depth Information
electronic spin states at both the atomic (conventional EMR) and the nanoscale
(ferromagnetic resonance, i.e., FMR) [
3
]. Information obtained from EMR spec-
trum depends upon the nature and form of specimen.
12.2 EMR Characterization of Nanoparticles
From a fundamental point of view, the study of nanoparticles is very important
since the physics of infinitely large systems is not applicable in the finite-size
particles [
4
]. Nanomaterials exhibit different properties from their coarse grained
materials. Specific properties lead to their technological importance. It is the reason
that they have attracted researchers these days. Therefore, the preparation and
characterization of nanoparticles are prime concerns of the scientific community.
In this chapter, EMR spectroscopy of metallic nanoparticles and metal oxide
nanoparticles along with some others have been discussed and we have tried to
avoid repetition from earlier review [
3
] unless it is specifically within the general
scope of the present article.
12.3 EMR of Metallic Nanoparticles
12.3.1 Silver Nanoparticles
EMR of silver nanoparticles embedded in SiO
2
matrix is reported by Mitrikas
et al. [
4
]. The magnetic properties were investigated in the low temperature region
between 4 and 300 K. CW EMR spectrum of the silver nanoparticles was found to
exhibit a modest homogeneous broadening character [
1
]. Authors have reported the
spin-lattice relaxation time was measured by pulsed EMR. However, good fit for
their data could not be obtained using the approach of Khaliullin et al. [
5
] for spin-
lattice relaxation of conduction electrons. This led to the need of detailed studies on
silver nanoparticles to understand their spin-lattice relaxation mechanisms. How-
ever, they could conclude that factors such as the particle diameters and the matrix
might play important roles in the spin-lattice relaxation.
12.3.2 Nickel Nanoparticles
Development of nickel nanoparticles has attracted attention of researchers because
of their unique properties and potential applications in a variety of fields including
electronics [
6
], magnetism [
7
,
8
], energy technology [
9
], and biomedicine [
10
,
11
]. Alonso et al. [
12
] have reported study on the characterization of the nickel
