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日
期：2010.08.09
指導老師：林克默
學
生：陳冠廷
Outline
1. Introduction
2. Experimental
3. Results and discussion
4. Conclusions
1.Introduction
• Nanocomposite ZnO–Ag thin film containing nano-sized Ag
particles have been grown on glass substrate by spin-coating
technique using zinc acetate dihydrate as starting precursor in
2-propanol as solvent and monoethanolamine as stabilizer.
Silver nanoparticles were added in the ZnO sol using silver
nitrate dissolved in ethanol-acetonitrile. Their structural,
electrical, crystalline size and optical properties were
investigated as a function of preheating, annealing
temperature and silver content.
2. Experimental details
•
ZnO sol was prepared using zinc acetate dihydrate,Zn(C2H3O2)22H2O, 3.1 g, (99.9%) (Sigma–
Aldrich) (ZA) as precursor, dissolved in the mixture of isopropyl alcohol,15 mL (99%) (Merck)
(IPA) as a solvent, and monoethanolamine,0.86 mL (99%) (MEA) (Sigma–Aldrich) as a
complexing agent while stirring at 60 C for 1 h to achieve a transparent ZnO sol and aged for
1 day.
•
Silver sol was prepared using silver nitrate, AgNO3, 0.777 g, (99.9%) (Aldrich) as precursor,
dissolved in the mixture of ethyl alcohol, 5 mL (98%) (Merck) as a solvent and acetonitrile, 5
mL (99.9%) (Aldrich) as a complexing agent while stirring at 25 ℃ for 1 h. ZnO sol was added
to the silver sol under gentle stirring to attain a sol mixture with [Ag] = 0.175 M and [ZnO] =
0.541 M (molar ratio of Agto ZnO was 32%). The resultant sol was left to age for3 days at
ambient temperature in a closed vessel.
•
Similar sol mixtures with an appropriate ratio of ratio of Ag to ZnO sol were prepared to
attain a sols of [Ag] = 0.148 M, [Ag] = 0.110 M and [Ag] = 0.068 M. The molar ratio of Ag to Zn
for these sol mixtures was 20, 12 and 5%respectively.
•
In the present study the nanocomposite ZnO–Ag thin films were deposited on glass substrate
using sol–gel spin coating technique with 3,600 rpm for 45 s.The glass substrate was cleaned
with acetone, rinsed with deionized water and subsequently dried using a flowing dry
nitrogen gas before deposition.
3 .Results and discussion
• Fig. 1 TG-DTA curves of a pure ZnO and b nanocomposite
ZnO–Ag, [Ag] = 0.148 M gels, which had been dried in 100 ℃
Fig. 2 XRD pattern of ZnO–Ag thin films,
[Ag] = 0.148 M preheated at different
temperature a 300 ℃, b 275 ℃, c 250 ℃,
d 225 ℃ and e 200 ℃ and annealed at
550 ℃
Fig. 3 XRD pattern of nanocomposite
ZnO–Ag, [Ag] = 0.148 M at different
annealing temperature a 850 ℃, b 750
℃, c 650 ℃ d 550 ℃, e 450 ℃ and f
350 ℃
Fig. 4 XRD pattern of ZnO–Ag thin
films with different molar ratio a [Ag]
= 0.175 b [Ag] = 0.148 M c [Ag] =
0.110 M d [Ag] = 0.068 M and e pure
ZnO thin films, preheated at 275 ℃
and annealed at 550 ℃
Fig. 5 XRD pattern of ZnO–Ag, [Ag] =
0.148 M thin films with different layers
number a 8, b 6, c 5, d 4, e 2 layers,
preheated at 275 ℃ for 10 min and
annealed for 2 h at 550 ℃
Fig. 6 FT-IR spectrum of a pure ZnO b nanocomposite ZnO–Ag, [Ag] =
0.148 M annealed at 550 ℃
Fig. 7 Cross-section SEM image for one layer
of nanocomposite ZnO–Ag film with 379 nm
thickness (top), a SEM image of pure ZnO
thin film b nanocomposite ZnO–Ag, [Ag] =
0.148 M thin film preheated in 275 ℃ and
annealed at 550 ℃, with 30,000
magnifications
Fig. 8 AFM images of surface morphology the thin films a pure ZnO
b nanocomposite ZnO–Ag, [Ag] = 0.148 M preheated at 275 ℃ and
annealed at 550 ℃
Fig. 9 Optical absorption spectra of
a nanocomposite ZnO–Ag,
[Ag] = 0.110 M thin film b
nanocomposite ZnO–Ag, [Ag] =
0.068 M c pure ZnO thin film
preheated at 275 ℃ and annealed
at 550 ℃
Fig. 10 Optical absorption
spectra of nanocomposite ZnO–
Ag, [Ag] = 0.148 M thin film
preheated at 275 ℃ and
annealed at a 350 ℃ b 450 ℃
and c 550 ℃
Fig. 11 Transmission electron microscopic (TEM) images of nanocomposite ZnO–Ag,
[Ag] = 0.148 M dried sol at 100 ℃ and preheated at 275 ℃ with a 80,000 and b
100,000 magnifications
4. Conclusion
• In summary we have successfully synthesized nanocomposite
ZnO–Ag thin films through a simple sol–gel method at room
temperature.
• The influence of silver content, preheatingand post-annealing
temperature on the structuraland photonic properties of
nanocomposite ZnO–Ag thinfilm is investigated.
• Crystalline phase and optical absorptionof nanocomposite
ZnO–Ag thin films was improved atoptimal preheating and
annealing temperature of 275 and550 ℃ respectively. The
amount of Ag content was foundto control the absorption
band.
Thank you for your attention