Chemistry Reference
In-Depth Information
. reported EuS nanoparticles prepared in liquid
ammonia [206]. The typical synthetic procedures involve the
dissolution of Eu metal in liquid ammonia and the introduction of
H
Yanagida
et al
S as the sulfur source. The yielded nanoparticles can be collected
by simply evaporating the solvent. A similar route reported by
Kataoka
2
et al
. used thiourea as the sulfurization reagent [207].
1.9
Summary
The study on the synthesis of rare earth nanomaterials is still ongoing
due to numerous interests of such materials in various applications.
Though considerable success has been achieved up to date, several
challenging scientific aspects of various synthesis techniques are yet
to be addressed:
1. The detailed formation mechanisms of nanomaterials in many
systems are yet unclear, or simply in the stage of presumptions,
which lacks concrete and supportive experimental evidences.
Thus, it is of urgent necessity to develop in situ and real-time
monitoring methodologies with high sensitivities, so as to
allow for insightful perspectives of the reaction process.
2. The synthetic routes developed so far seem less effective
for some systems, for example, Y-Ba-Cu-O-type compounds,
Eu(II)-associated materials, metallic rare earth nanomaterials,
owing to either the complexity in chemical composition
and reactivity of each individual species, or the stringent
experimental conditions required.
3. Nanoparticles with good crystallinity, few defects, and high
applicability are still in urgent demand, especially those with
luminescent properties, in which case the defects present
in the nanoparticles would severely quench the excited
emissive species, and thus largely hamper the luminescent
efficiencies.
4. The fabrication methods for hybrid/composite nanostructures,
which could afford integrated functionalities and improved
performances, are yet limited and usually involve laborious
fabrication procedures. Simple and efficient methods are
still desired to assemble the rare earth nanomaterials with
other functional entities, such as organic dyes, semiconductor
quantum dots, noble metals, and magnetic nanoparticles.
