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www.tyndall.ie
New Photonic Band Gap Materials via the Synthesis and Assembly of
Dielectric-Metal-Dielectric Particles
Bartosz IżowskiAdvanced Materials & Surfaces Group
Warsaw University of TechnologyPoland
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“ If only were possible to make materials in which electromagnetically waves cannot propagate at certain frequencies, all kinds of almost-magical things would happen”
Sir John Maddox, Nature (1990)
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Outline
1. Introduction
• Photonic crystals
• Opals in nature
2. My project
• Synthesis
• Research
3. Results
4. Conclusions
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Introduction
Photonic Crystals – semiconductors of lightSemiconductors
Atomic length scalesNatural structuresControl electron flow
Photonic Crystals
Length scale ~ Artificial structuresControl e.m. wave propagation
Photonic Crystals periodic dielectric structures• interact resonantly with radiation with wavelengths comparable to the periodicity
length of the dielectric lattice• dispersion relation strongly depends on frequency and propagation direction
Periodic array of atoms
Periodic variation of dielectric constant
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Introduction
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22)(max sin2
effnd hklBragg-Snell’s law :
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My project
1. Synthesis
• Silica particles – Stöber method
• Silica @ silver
• Silica @ silver @ silica
2. Manufacturing of Photonic Crystals – controlled evaporation self-assembly
3. Reflectance / Transmittance results
4. Conclusions
GOALStudies of the photonic crystal properties (band gap properties)
in dielectric-metal photonic crystal systems
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Synthesis
Face-Centered Cubic Lattice
Controlled Evaporation self-assembly method
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Synthesis
• Silica colloids were prepared using the Stöber synthesis
Si(OC2H5)4 + 4 H2O Si(OH)4 + 4 C2H5OH
Si(OH)4 → SiO2↓ + 2 H2O
In ethanol, in presence of NH3
• These colloids are charged, stabilised in water and in alcohols by electrostatic interactions•Zeta potential = - 55.3 mV
EtOHNH4OH
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Synthesis
[NH4OH] ml
Stirring time [hrs]
Particle size [nm]
Standard deviation [%]
1.75 2 108 12.92.5 3 151 135 1 290 6.55 2 272 7.95 3 297 6.36 2 411 7.2
100 150 200 250 300 350 400 4501
2
3
4
5
6411,4
272,2
289,8
297,8
151,2
108,3
[ NH 4O
H ]
mL
Particle size [nm]
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Results
Size = 411 nmStd.dev = 7.2%
Size 108 nmStd.dev = 12%
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Silver shell preparation
core @ shell preparation
Preparation of silver nanoparticles decorating of silica surface
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SampleZeta
potential [mV]
pH
Silica - 55.3 9.98
silica@PEI 35.7 8.8
Silver NP. - 50.4 7.84
silica@silver 26.3 9.58
0
100000
200000
300000
400000
500000
600000
700000
-200 -100 0 100 200
Tota
l Cou
nts
Zeta Potential (mV)
Zeta Potential Distribution
Record 75: BI4 1 Record 76: BI4 2 Record 77: BI4 3
0
100000
200000
300000
400000
-200 -100 0 100 200
Tota
l Cou
nts
Zeta Potential (mV)
Zeta Potential Distribution
Record 95: BI39+PEI 1 Record 96: BI39+PEI 2 Record 97: BI39+PEI 3
0
100000
200000
300000
400000
500000
600000
700000
-200 -100 0 100 200
Tota
l Cou
nts
Zeta Potential (mV)
Zeta Potential Distribution
Record 99: BI41-DAP 1 Record 100: BI41-DAP 2 Record 101: BI41-DAP 3
silica
silica@PEI
silica@silver
Zeta potential
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Formaldehyd reduction of silver-amine complex into the existing silver nanoparticles
Silver shell growth
Electroless plating
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Silica outer shell preparation
core @ shell @ shell preparation
1,3 – Diaminopropane (DAP)N,N-Dimethyldodecylamine (DMDDA)H2O / EtOH (1:4)TEOS Silica @ silver @ silica particles
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Zeta potential
sampleZeta
potential [mV]
pH
silica@silver 26.3 9.58
silica@silverDAP
9.01 7.93
silica@silverDAP - DMDDA
8.13 7.7
silica@silver@silica 19.5 9.05
0
100000
200000
300000
400000
500000
600000
700000
-200 -100 0 100 200
Tota
l Cou
nts
Zeta Potential (mV)
Zeta Potential Distribution
Record 99: BI41-DAP 1 Record 100: BI41-DAP 2 Record 101: BI41-DAP 3
0
100000
200000
300000
400000
-200 -100 0 100 200
Tota
l Cou
nts
Zeta Potential (mV)
Zeta Potential Distribution
Record 103: BI41-DAP-DMDDA 1 Record 104: BI41-DAP-DMDDA 2Record 105: BI41-DAP-DMDDA 3
0
100000
200000
300000
400000
500000
600000
700000
-200 -100 0 100 200
Tota
l Cou
nts
Zeta Potential (mV)
Zeta Potential Distribution
Record 91: BI44 CSS 1 Record 92: BI44 CSS 2 Record 93: BI44 CSS 3
silica@silver - DAP
silica@silver@silica
silica@silver – DAP - DMDDA
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Crystallization by controlled evaporation self-assembly method
H2O / EtOH 60°C
silica@silver film
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Arrangement
bare silica opal silica@silver opal
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Optical properties
300 400 500 600 700 8000.0
0.2
0.4
0.6
0.8
1.0
Abs
orba
nce
Wavelength (nm)
Silver NP Silica@silver Silica@silver shell Silica@silver@silica
UV-vis absorption spectra of nanoparticles.
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Optical properties
Reflectance and Transmittance spectra of bare silica opal measured at 10 ° incidence to the normal
600 8000
20
40
60
80
100
% T
% R
Wavelength (nm)
T R
10 ° to the normal
732
nm
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Optical properties
Reflectance spectra of bare silica opal (10 to 60 are the angle of incidence of light to the normal)
500 600 700 800 9000
20
40
60
80
100
120
% R
(A. U
.)
Wavelength (nm)
10 20 30 40 50 60
Bragg-Snell’s Law λmax = 2d111 (neff – sin2θ)1/2
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Optical properties
Reflectance spectra of silica@silver opal measured at incident angles from 10 to 60 degrees to the normal
600 8000
20
40
60
80
% T
% R
Wavelength (nm)
R T
10 ° incidence to the normal
805
nm
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Reflectance spectra of silica@silver opal measured at incident angles from 10 to 60 degrees to the normal
600 8000
10
20
30
% R
(A. U
.)
Wavelength (nm)
10 20 30 40 50 60
Optical properties
Bragg-Snell’s Law λmax = 2d111 (neff – sin2θ)1/2
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Conclusions
• Prepared monodispersed silica nanoparticles
• Prepared silver decorated silica nanoparticles
• Attempted silica@silver@silica CSS particles
• Characterized different steps of the CSS particle formation by ZP
measurements, UV-vis absorption spectroscopy and TEM analysis
• Photonic crystals of these materials are prepared and photonic band gap
properties are compared.
• Photonic band gap of silica@silver particles show a red shift from that of
bare opal.
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Acknowledgements
Supervisor: Prof. Martyn Pemble
Co-supervisor: Dr. Sibu C. Padmanabhan