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Oriented Attachment of ZnO Nanocrystals
journal contribution
posted on 2013-05-16, 00:00 authored by Dimitri Hapiuk, B. Masenelli, Karine Masenelli-Varlot, Dimitri Tainoff, Olivier Boisron, Clément Albin, Patrice MélinonSelf-organization
of nanoparticles is a major issue to synthesize mesoscopic structures.
Among the possible mechanisms leading to self-organization, the oriented
attachment is efficient yet not completely understood. We investigate
here the oriented attachment process of ZnO nanocrystals preformed
in the gas phase. During the deposition in high vacuum, about 60%
of the particles, which are uncapped, form larger crystals through
oriented attachment. In the present conditions of deposition, no selective
direction for the oriented attachment is noticed. To probe the driving
force of the oriented attachment, and more specifically the possible
influence of the dipolar interaction between particles, we have deposited
the same nanocrystals in the presence of a constant electric field.
The expected effect was to enhance the fraction of domains resulting
from the oriented attachment due to the increased interaction of the
particle dipoles with the electric field. The multiscale analytical
and statistical analysis (TEM coupled to XRD) shows no significant
influence of the electric field on the organization of the particles.
We therefore conclude that the dipolar interaction between nanocrystals
is not the prominent driving force in the process. Consequently, we
argue, in accordance with recent theoretical and experimental investigations,
that the surface reduction, possibly driven by Coulombic interaction,
may be the major mechanism for the oriented attachment process.