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growth.
138
HDA was also used as a capping agent and reaction solvent in the
preparation of GaAs QDs by the thermolysis of [
t
Bu
2
AsGaMe
2
]
2
. The resulting
particles were
ca.
3.2 nm in diameter, with a blue-shi
ed band edge and
broad emission. Powder XRD con
rmed small amounts of Ga
2
O
3
and In
2
O
3
,
and heating the material in air resulted in the formation of GaAsO
4
.
139
In
related work, the precursor [
t
Bu
2
AsInEt
2
]
2
was thermolysed in hot HDA to
give InAs particles
ca.
9 nm in diameter with similar optical properties to
those of GaAs described previously.
140
Notably, in this study the XRD pattern
is extremely clear relative to other III
d
n
1
y
4
n
g
|
4
V materials prepared by single-source
precursors described above and can easily be compared to the bulk di
-
rac-
tion pattern, possibly due to the large crystal domains in the bigger particles.
Group III
-
nitride materials made by solvothermal routes have been dis-
cussed in only a few reports, because of the lack of obvious precursors and
the metastability of certain materials, such as InN which decomposes at 400
C. Despite all e
cult to prepare by
solution routes. Several examples exist, based on azide-type structures; in
a route described by Dingman
et al.
, one of the
orts, nitride nanomaterials remain di
rst reports of single-source
solution routes to nitrides used the precursors [R
2
InN
3
]
n
(where R
alkyl
group), a ladder-type polymeric structure, which was found to be insoluble in
most hydrocarbons, yet soluble in Lewis base solvents. Thermolysis of the
isopropyl precursor in diisopropylbenzene resulted in amorphous material,
but inclusion of H
2
NNMe
2
resulted in InN nano
¼
bres, grown from an indium
nanodroplet (produced by the reduction of the precursor by the H
2
NNMe
2
).
The material, characterised by XRD and electron microscopy, appeared to
grow
via
the SLS mechanism described in Chapter 1.
141
Gallium azides have
also been explored as potential precursors to GaN; [Et
2
Ga(N
3
)]
3
,(N
3
)
2
Ga
[(CH
2
)
3
NMe
2
] and (Et
3
N)Ga(N
3
)
3
have been used in re
.
uxing triglyme,
yielding particles
ca.
200 nm in diameter, signi
cantly larger than other
similarly prepared nanoparticles. Despite the large particle size, no XRD
patterns were obtained, indicating the poor crystallinity of the materials.
Broad emission towards the blue end of the optical spectrum was observed
despite the amorphous character.
142
InN with a cubic crystalline core has also been prepared from the ther-
molysis of InN
3
(CH
2
CH
2
CH
2
NMe
2
)
2
in TOPO, yielding particles
ca.
2
-
10 nm
in diameter. The band edge was determined to be
ca.
570 nm, with emission
observed at 690 nm, although emission from the capping agent at 550 nm
was also observed. This is notable, as a de
nite capping agent was utilised,
unlike the previous example.
143
Nanoparticles of GaN, InN and AlN have also
been prepared by thermolysis of M(H
2
NCONH
2
)
3
Cl
3
(M
Al, In, Ga) in TOA,
although few details were provided.
144
In a detailed study, InN particles with
a hexagonal crystalline core were produced by the reaction between InBr
3
in
toluene with NaN
3
yielding an azide intermediate which was gently ther-
molysed to yield the desired product. As well as a high-pressure-based route,
a bench-top ambient-pressure synthesis using TOA as a capping agent was
described, which was possible due to the slight solubility of InBr
3
in toluene
(previously, other halides were found to be insoluble and unsuitable for
¼
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