8 Magnetic Self-Assembling of Spherical Co Nanoparticles …
195
Fig. 8.8 TEM images of 2D ordered arrays of native fcc-Co polycrystals obtained by the micellar
approach a 3.9 nm (S1), b 4.6 nm (S2), c 7.7 nm (S6), d 9.3 nm (S7)
2D ordered arrays, the as-synthesized fcc-Co polycrystals can be submitted to a
dry-annealing process (3).
(1) Whatever the size of the as-synthesized fcc-Co polycrystals, TEM study
(Fig. 8.8a–d) shows the formation of 2D ordered arrays with hexagonal
symmetry [21]. These organizations are determined by both the diameter and the
length of the C12 coating agent. For 3.9 nm, the mean center-to-center distance
between particles (Dc-c) and interparticle gap (Di-p) are 5.9 nm and 2.1 nm,
respectively (Table 8.3). Taking into account length of dodecanoic acid in the
cis–trans configuration, i.e., 1.77 nm, the low D i-p value indicates interdigitation
between the C12 alkyl chains. The use of larger Co NPs, e.g., 4.6, 7.7 and 9.3 nm
results in a significant decrease of the Di-p values found equal to 2.3, 1.6 and
1.4 nm, respectively. This behavior is attributed to the van der Waals attractions
between the metallic core, which magnitude increases with the particle volume.
195
Fig. 8.8 TEM images of 2D ordered arrays of native fcc-Co polycrystals obtained by the micellar
approach a 3.9 nm (S1), b 4.6 nm (S2), c 7.7 nm (S6), d 9.3 nm (S7)
2D ordered arrays, the as-synthesized fcc-Co polycrystals can be submitted to a
dry-annealing process (3).
(1) Whatever the size of the as-synthesized fcc-Co polycrystals, TEM study
(Fig. 8.8a–d) shows the formation of 2D ordered arrays with hexagonal
symmetry [21]. These organizations are determined by both the diameter and the
length of the C12 coating agent. For 3.9 nm, the mean center-to-center distance
between particles (Dc-c) and interparticle gap (Di-p) are 5.9 nm and 2.1 nm,
respectively (Table 8.3). Taking into account length of dodecanoic acid in the
cis–trans configuration, i.e., 1.77 nm, the low D i-p value indicates interdigitation
between the C12 alkyl chains. The use of larger Co NPs, e.g., 4.6, 7.7 and 9.3 nm
results in a significant decrease of the Di-p values found equal to 2.3, 1.6 and
1.4 nm, respectively. This behavior is attributed to the van der Waals attractions
between the metallic core, which magnitude increases with the particle volume.