Chemistry Reference
In-Depth Information
in hexagonal phase (RE = La, Ce, Pr, Nd. Sm, Eu, Gd) exhibited nanorod
bundles morphology, and the products in tetragonal phase (RE = Tb,
Dy, Ho) exhibited particle-like morphology.
. reported the preparation of nearly monodisperse
spherical aggregates of CeO
Yan
et al
nanocrystals in ionic liquids (IL), where
the IL 1-hexadecyl-3-methylimidazolium bromide (C16MimBr) acted
as both the template and solvent. The spherical aggregates were
100
2
nanocrystals (ca.
3.5 nm) as building units, and thus exhibiting 3D open mesoporous
structures [197]. They also used the IL route to prepare NaYF
−
150 nm in diameter, composed of small CeO
2
4
nanoclusters in combination with microwave irradiation [198].
Chen
et al
.
synthesized REF
(RE = La, Ce, Pr, Nd, Sm, Eu, and Er),
3
CeF
nanocrystals with good uniformity
in different ILs (1-octyl-3-methylimidazolium hexafluorophosphate,
1-octyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-
methylimidazolium hexafluorophate). The ILs acted as both solvents
and templates, and during the reaction process, the PF
:Tb
3+
, as well as LaF
:Eu
3+
3
3
−
−
and BF
6
4
anions underwent partial hydrolysis and thus provided the fluorine
source [199]. Bühler and Feldmann reported microwave-assisted
synthesis of LaPO
:Ce,Tb nanocrystals in ILs [200]. Typically, a
solution of rare earth salts in IL and cosolvent was added to another
portion of IL solution containing phosphate precursors, and the
obtained opalescent mixture was heated by microwave at 300
4
°
C for
10 s.
Okuyama
. employed a modified aerosol decomposition
method to prepare CeO
et al
particles, with addition of eutectic salts
to the solution [201]. The eutectic salts were found to be helpful to
reduce the particle size and enhance the crystallinity. Similarly, Hu
et al
2
. also used eutectic salts in the composite-hydroxide-mediated
synthesis of ceria [202]. Huang
. fabricated ultrathin crystalline
Gd-dope ceria films by dc sputtering and subsequent oxidation
treatment [203].
Li
et al
. reported the general synthesis of a series of metal oxide
hollow spheres (SnO
et al
, etc.)
using carbonaceous polysaccharide microspheres as templates (Fig.
1.22) [204]. The metal sources in solution were absorbed onto the
functional surface layer of carbonaceous saccharide microspheres,
and subsequent calcinations and oxidation allowed the absorbed
species to densify and cross-link into hollow spheres, while the
templates were removed.
, Al
O
, La
O
, Y
O
, Lu
O
, CeO
, TiO
, ZrO
2
2
3
2
3
2
3
2
3
2
2
2
