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Nano-particle prepared from sol-gel method

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Title: Nano-particle prepared from sol-gel method


1
Nano-particle prepared from sol-gel method
1. TiO2
Titanium tetra-iso-propoxide
diethanolamine
Polyethylene glycol
SiO2 substrate
Solution I with Polyethylene glycol Solution II
without Polyethylene glycol
2
Solution I Particle size 1015nm. Space with a
width of several nanometers existed between the
crystallites. Anatase phase transforms to rutile
above 650oC
Solution II Dense structure, Particle size 15nm
and connected each other. Particle size increases
to 50nm heated above 650oC and the crystallites
had connected hard each other.
3
Anatase powder
The relatively high intensities indicates that a
significant amount of the crystallites arranged
with c axis perpendicular to the surface
amorphous
4
2. Au-SiO2
TEOSC2H5OH
HAuCl44H2OH2O C2H5OHHCl
TEOS H2O C2H5OH Au 12100.420.028
r H2O/TEOS
mixing and stirring vigorously at room temp for
5mins, then kept tightly in container at 40oC for
various of time prior to dip-coating
Dip-coated film is transparent and almost
colorless, film is heated at 500oC for 10mins,
the film exhibits red to purple color
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MAE monoethanolamine NHC2H4OH
227nm and 314nm are assigned to 1Ag1g?1E1u and
1Ag1g?1E2u. The changes of the intensities of the
peaks suggest the change in the coordination
state in the gold complex
9
  • Effects of the exposure of the gel film to MEA
    vapor prior to heat-treatment
  • Decrease the size of gold particle to 5nm.
  • 2. Increase the amount of trapped gold particles
    in silica matrix.
  • Possible reasons
  • The pore size of silica matrix is smaller.
  • 2. Precipitation of gold hydroxide, smaller
    gold hydroxide particles are fixed in the gel.
  • 3. Change the coordination state of Au3.

10
3. CdS in SiO2 gel
TEOS, C2H5OH, H2O,HCl in molar 1110.27
C2H5OH, NH4OH in molar 4 1.25 0.005
hydrated cadmium acetate C4H6CdO42H2O
CH3OH 0.05 1
Dried in oven Dried gel Gel Heat treatment
Heat treated in H2S at 200oC for 2hrs
Journal ofCrystal Growth 144 (1994) 141149
11
Dimethyl sulfoxide (CH3)2SO
Heat treated to various temp
Journal of solid state chemistry 118, 1-5 (1995)
12
Photonics and Nanostructures Fundamentals and
Applications 5 (2007) 156163
13
CdS01 TEOSCd10.5 Particle size 1.66nm CdS02
TEOSCd11 Particle size 2.99nm Absorption peak
for CdS bulk at 520nm
14
TiO2 tubules and fibrils
(Ti(OCH(CH3)2)4(5ml) C2H5OH(25ml) stirred at 0oC
Add C2H5OH(25ml) H2O(0.5ml) 0.1MHCl(0.5ml) at
15oC
After 60 s at 15oC the resulting mixture turned
milky white (sol formation).
alumina template membrane was immediately dipped
into this solution for an immersion time that was
varied between 5 and 60 s. dried in air for 30
min at room temperature.
placed in a tube furnace (in air), and the
temperature was ramped (50 C h-1) to 400 C. The
membranes were heated at this temperature for 6
h, and the temperature was ramped back down (30
C h-1) to room temperature.
15
????? AnodiscTM13(0.2?m, ??50 ?m)
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16
Electron Microscopy. SEM images of the 200 nm
diameter tubules and fibrils were obtained as
follows One surface layer was removed, and the
membrane was glued to a piece of paper towel. The
membrane was glued with the polished face up. The
resulting composite was immersed into 6 M aqueous
NaOH for 10 min in order to dissolve the alumina.
When the sol was 5 C, thin-walled tubules were
obtained even at long immersion times (1 min). In
contrast, when the sol was maintained at 20 C,
solid TiO2 fibrils were obtained even after very
brief (5 s) immersion times.
17
Bundles of the TiO2 nanostructures were observed.
The bundle sizes observed ranged from as small as
2-4 fibrils to as large as 10 or more fibrils.
The main feature in figure that runs diagonally
across the image consists of two bundles of
fibrils, one on the right edge of the main
feature and one on the left edge. In this case
the bundles consist of approximately 3-4 fibrils.
A second set of two bundles is observed below
this main feature this second set of bundles
also proceeds diagonally across the image but at
a smaller angle.
TEM image for TiO2 Fibrils Prepared in the
membrane with 22 nm diameter pores. It shows a
bundle of 15 nm diameter TiO2 fibrils.
18
To 20 mL of ethanol was added 0.35 g of zinc
acetate, and the resulting mixture was boiled
until a clear solution was obtained (ca. 30 min).
The volume was returned to 20 mL with ethanol,
and 0.06 g of LiOHH2O was added. The resulting
solution was ultrasonicated until a white
suspension was obtained (ca. 1 h). The alumina
membrane was immersed into this sol for 1 min,
removed, and allowed to dry in air at room
temperature for 30 min. The membrane was then
heated in air at 120 C for 6 h.
19
Nano-battery
AgI-Ag nanowires
(a) Cross-sectional FE-SEM image of AgI/Ag
embedded inside the AAO membrane. ( b) FE-SEM
top-view image.
20
The ionic conductivity of single AgI/Ag was
estimated to be on the order of 1.58.0 103
(?-cm)1 Compared with that of room-temperature
bulk polycrystalline AgI (ca. 105106 (?-cm)1
an enhancement by two to three orders of
magnitude was demonstrated. This enhanced ionic
conductivity may be attributed to interfacial
defects and mesoscopic multiphase effects as a
result of stacking-fault arrangements.
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