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Particle Processing Research
Terry A. Ring
Chemical Engineering
University of Utah
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Presentation Goals
Introduce My Work to NSFShow Breadth of Coverage
Fundamentals of Ceramic Powder Processing and Synthesis
Product BoxShow Depth of Coverage in One Area
Nano-sized Cluster NucleationNSF - Program Vision
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Ceramic Particle Processing Research
Crystallization Inhibitors - Trane Corp.
Nifedipine (Heart Drug) Sintering-Pfizer, Bayer
Scaling Chemicals-Spa Natural
Bio-Cements as Bone Replacement Materials - Sultzer, Mathis
Ceramic Thin Films As Chemical Sensors - RMA Associates
BaTiO3 Multi-layer Capacitors- Phillips(Taiwan)
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Ceramic Particle Processing Research-con’t
Multi-layer Chip Support Sintering - Metalor, IBM, Dupont
Vermiculite Based Insulation Materials - ABB
Silica Aerogels for Building Insulation - Airglass, SA
Nitride coating for Al2O3 Platelets for Cutting Tools - Amysa, SA
Pultrusion Process for Carbon Fiber Reinforced Composite - Easton
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Precipitation Research
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Agglomeration in CSTR
Reactant A Reactant B
Outlet
Overflow
Mixing �
Shaft Baffles
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Nano-sized Cluster Nucleation
IntroductionClassical Nucleation Theory &
LimitationsNew Theory & Findings
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Introduction
Unique Properties of Nanosized Particles Plasmon Resonance -color due to size, color
change due to adsorption-sensors Between Bulk and Atomic Electrical Properties Catalytic Properties
Magic Cluster Sizes C60, C70, C nanotubes, Na clusters of 8, 20, 40, 58 and 92
Silicon Particles
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Stimulated Emission CdS Nano-Clusters-Laser
Lasing only when quantum dot concentration is sufficiently high.
Stimulated emission>Auger recombination
Klimov, V. Mikhailovsky, A.,Xu, S., Hollingswork, J., Malko, A., Bawendi, M., Eiser, H-J., Leatherhead, C.A.
Science 290,314 (2000) Science 287,1011 (2000)
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Semiconductor Nanocrystals Breakdown Organic Pollutants
Environmental remediation
Solar photocatalysis/fuel production
Environmental remediation
Solar photocatalysis/fuel production
0
100
200
300
400
500
600
700
800
3 4 5 6 7 8
Ab
sorb
ance
(25
0 n
m)
Elution Time (min)
MoS2 Photocatalyst
alkyl chloride
t=1 hour
t = 0
3 nm MoS2 nanocrystals photo-oxidizean alkyl chloride in solution using only visible room light
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Fullerene Synthesis
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Fullerene Synthesisodd vs. even clusters
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Nanoparticle Synthesis
Desperate Need to Control and Scale-up!!
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Nanoparticle Synthesis = Nucleation (no Growth!!)
Classical Nucleation Theory Free Energy in two pieces
G(r) = -(v r3/Vm)RT ln(S)+ a r2
G(i) = - i kBT lnS+ a ao2i2/3
where v(=vr3) is the volume and a(=ar2) is the area of the aggregate,is the molar volume of the precipitate, is the surface free energy per unit area.
X(atom) +X(r*-atom)<----> X(r*)CriticalSize, r*
G(i)
S
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New Nucleation Theory
Multi-Atom Addition Free Energy Driving Force for Diffusion and
Addition
New Attributes Predicts transients of Cluster Size Distribution Predicts Induction Time
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Population Balance - Multi-atom Addition
Numerical solution required except
ij = 1 Ck = • Smoluchowski, Physik Zeits, 17,557(1916)
ij= i+j Ck = , u= 1-exp(-t)
• Scott, W.T., J. Atmos. Sci., 25,54(1968)
ij=i*j Ck = tk-1 kk-2 exp(-k t)/k!, t 0• McLeod, J.B., Quant, J. Math Oxford, 13,119 and 193(1962).
1
1
)2/1(
)2/(
k
k
t
t
!
)exp())(1( 1
k
kukuu k
ii
kikiki
k
iikik CCCCtC
1,
1
1,2/1/
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Collision Frequency
Jij= -(Dij Ci )/(ri+rj)*4(ri+rj)2*Cj *exp(-Gij/kBT)) = ij CiCj
This Collision Frequency compares to others by various Mechanisms:
Collision Frequencyij =
JijCiCj
Kolmogorovmicrolengthscale = /ueddy size = Tank size = L
Diffusion Dij*4 (ri+rj)Free Energy
-Dij exp( TkG
B
ij) 4
(ri+rj)
Viscous Shear 4/3• (ri +rj) 3 6/u <
Transition 2.36*5/12 -1/4
(ri+rj)8/36/u < < 25/u
Inertial 6.87*1/3 (ri+rj)7/3 25/u< < L/2
macro 7.09*(L)1/3 (ri+rj)2 L/2< ~L
Dij = µTkB6 *[
1ri +
1rj ] ri=ao*i1/3
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Collision Free Energy, Gij
Gij =G(i+j)-(G(i)+G(j))
G(i) = - i kBT lnS + a ao2i2/3
i or j > 1Gij =G(i+j)-(G(i)+G(j))= a ao
2(i+j)2/3 - i2/3 - j2/3]
i = 1, any jGij = - i kBT lnS + a ao
2(i+j)2/3 - j2/3 ]
j = 1, any iGij = - j kBT lnS + a ao
2(i+j)2/3 - i2/3 ]
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Effect of exp(-Gij/kBT) on Nucleation
ij=(i+j)exp(-Gij/kBT),Numerical Solution- C
ij=(i+j), Analytical Solution, N
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Binding Energy per Li atomKouteckky, J. and Fantucci, P., Chem. Rev., 86,539-87(1986).
0 10 20
18.3358
-0
( )GSis
....4 a12
.kB T
ig
2
3 1
ig
.0 ig
201 ,is ig
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Lin Optimal GeometryBE/n(eV)
Li3 3.2 (C2v) 0.35Li3 3.3 (C2v) 0.34*Li4 4.2(D4h) 0.51Li4 4.3(Td) 0.41Li5 5.2(D3h,C3v) 0.56Li5 5.3(C4v) 0.53Li5 5.4(D5h) -Li6 6.2(C5v) 0.62Li6 6.3(Oh) 0.60Li6 6.4(D3h) 0.63**Li7 7.2(C3v) 0.61Li7 7.3("fcc") 0.61Li7 7.4(??) -Li8 8.2(C2v) 0.71Li8 8.3("fcc") 0.65Li8 8.4("bcc") 0.60Li8 8.5(??) -
Cluster Binding Energy
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Activation Energy for i+j Cluster
Calculated from EAi,j = [ ji
BE
*] -
ji
jj
BEii
BE oo
][
, [ji
BE
*]
values are taken from Table 3 using BE*i +.j
BE*corresponding
to a deformed structure of each cluster.
i / j 1 2 3 4 5 6 7 81 -kBT lnS0.34 0.51 0.56 0.62 0.61 0.71 0.652 - 0.41 0.53 0.60 0.61 0.65 0.65 -3 - - 0.63 0.61 0.60 0.65 - -4 - - - 0.60 0.65 - - -
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Structural Classical
0 1 106
2 1063 10
60
0.5
1
C,m 1
N( ),.m t 1
C,m 2
N( ),.m t 2
.m t0 0.05 0.1
0
0.5
1
C,m 1
N( ),.m t 1
C,m 2
N( ),.m t 2
.m t
0 1 2 3 4 5 6 7 8 910
0.9999
4.63056e-33
N ,.tmax
2t k
C,
tmax
2k
N( ),.tmax t k
C,tmax k
9k0 1 2 3 4 5 6 7 8 910
1 1014
1 1013
1 1012
1 1011
1 1010
1 109
1 108
1 107
1 106
1 105
1 104
0.0010.01
0.11
,.tmax
2t k
,tmax
2k
( ),.tmax t k
,tmax k
1
k
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New Nucleation Theory
Dramatic effect for stable clusters, k=2,4,8,… Magic Clusters
Magic Clusters Affects Synthesis PathNot One but Multiple Critical Cluster
Sizes Nucleation Rate, I= dCk*/dt
Depends on Synthesis Path
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Crystalloluminescence
0 2 40
0.2
0.4
0.6
0.8
Collision Trajectory, R/re
BE
/ n
(eV
)
BE (i+j)
o
BE j
o BE i
o
+
BE j
BE i
+* *
²E
EACrystallo- luminescence
Figure 3 Collision trajectory for collision between i=3 and j=4 clusters,showing ground state energies before and after collision, as well as theactiviation energy of collsion.
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Crystalloluminesent Spectrum
Intensity vs Energy Intensity =
collisions/per unit time = photons/unit time
Wavelength E = hc/l
Human eye detection @ 3x104photons/cm2/s at λ 510 nm
0 0.5 1 1.5 2 2.51 10
141 10
131 10
121 10
111 10
101 10
91 10
81 10
71 10
61 10
51 10
40.001
0.01
0.1
I,i k
E,i k
eV
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Similar to Line Spectra
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Is this another cold fusion?
An effect produced by a barely detectable cause. Data on the edge of detectability Measurements are attributed to greater accuracy Fantastic theories are offered. Criticisms are met by ad hoc excuses thought up
on the spur of the moment. The ratio of supporters to critics rises up to ~50%
and then falls gradually to oblivion.
From1953 Lecture by Irving Langmuir
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Another cold fusion? Cont.
Researcher avoids designing experiments that would confirm whether or not an effect actually exists. (D. Rousseau, 1982).
Pressures to publish prematurely (Broad, W. and Wade, N., 1982.)
• Being scooped.• Notoriety.• Potential for money to be made.
More common in fields with reliance on statistically weak data. (N. Turro, 2001)
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Crystalloluminescence• Term Schoenwald in 1786
30 References 1786 and 1957 • “An understanding of crystalloluminescence in not too satisfactory at the present
time,” E.N. Harvey 1957
Examples: NaCl, KCl, NaF, AsCl3, K2SO4, As3O3, Sr(NO3)2,, CoSO4, K2CO3, KHSO3, NaKSO4, NaKCrO4, NaKSeO4, Na2SO4,
benzoic acid, and ice, water.
16 References 1957-1991 (15 Russian, 1 US + 1 Italian Review)
“It is not possible to … provide either a unifying physical picture of the microscopic mechanism governing
(crystalloluminescence) or a physical rule that allows conditions...where the phenomenon is stronger,” Barsanti, M. &
Maccarrone,F., 1991
3 References from 1991-2000 (2 India, 1 Russian) - Experiments
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Experimental Observations
Delay time is a function of concentration & mixing
Flashes are Short < 80 ns
Peak Count rates ~5-8x105 photons/s
Temporal & Spatial Bunching of Flashes
340nm<λ<380 nmFaint Blue White Light
Gibbon, M.A., Sopp, H. , Swanson, J., and Walton, A.J., J. Phys. C. 21,1921(1988).
Saturated NaCl + Conc. HCl - 120 s observation time
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Spectra Has Series of Peaks
Lines are Different from Thermal
Luminescence Photoluminescence
Impurities in Crystal have a Big Effect on Spectrum
Rabinerson, A.I. Wladimirskaya, M.A., Acta Physicochimica URSS, 10,859(1939)
BaSO4 Crystallization (20 min. exposure)Lines 1935Å-1945Å1976Å-1991Å2021Å-2037Å2145Å-2165Å2228Å-2300Å2300Å-2326Å
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New Theory’s Predictions
Predicts Crystalloluminescent Spectrum Method to Quantitatively Measure
Nucleation
Potential Real World Examples H2O Condensation Nucleation Interstellar Dust Nano-nucleation Light from Deep Sea Vents
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Super Novae
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Nanocluster, Ti14C13 with emission peak at 20.1 microns is seen in Egg Nebula byA.G.G.M. Thielens and M.A. DuncanScience 288,313(2000)
this joins some 120 other small molecules identified in the vicinity of stars, interstellar gas and dust clouds
Experimental Verification
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Interstellar Dust Clouds - Light from the Fringe - Crystalloluminescence due to Nanocluster Nucleation
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NSF
Particulate and Multiphase Program 1. Aerosols and colloids 2. Nanostructures 3. Granular flows 4. Multiphase processes related to
particles, droplets, and bubbles 5. Hydrodynamical multiphase analysis 6. Specific tools
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Nanotechnology has acquired National Status
National Nanotechnology Initiative $500M proposedfor FY01 Federal Budget
Usher in the “Next Industrial Revolution”
Develop and explore the “rules and tools” of nanotechnology
Education and SocietalImplications
President Clinton’s Jan. 21, 2000 announcementof a “National Nanotechnology Initiative” in a speech from the California Instituteof Technology.
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Nanoscience -- behavior of materials at the nanoscale is Nothing like that at the large scale
Properties not predictable from those at large scale
Different physics and chemistry emerges
New phenomena associate with:
Lead to:Measured Yield Point
Light from Si
Catalysis from Pd clusters
GPa strength from Au
Pyrene hydrogenation
– Electronic confinement
– Preponderance of surfaces and interfaces
– Quantized effects
– New modes of electronic and thermal transport
– Different manifestations of thermodynamic properties, phase transitions, and collective phenomena
– New chemical reactivities
– New mechanical properties--strength, friction, wear
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Many Particulate Problems in Nanotechnology
Lasers, CatalysisPhotonic Crystals - optical computingPhotonic Light PipesNano TiO2 Solar CellsNanotubes - computer wires, transistors Nanotube Light Emission - DisplaysNanocomposites - tunable lasers
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Layered Structures
Taylored Materials Electronics/photonics
Novel Magnets
Tailored hardness
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Defects in Ordered Arrays Bend Light
Optical Semiconductors
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Hexagonal Packing of Spheres
Light Diffraction
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Photonic Crystal Light Pipe
Light PipeLight Leaving Pipe
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Quantum Computing-
poly-Si
Si substrate
Light TrapsStopping Light without Absorption
Yablonovitch, E., 1986.
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Coupling to Biology
Sol-gel (or Micelle structures) for drug delivery Diffusive Collisions ~ R(DF+2-3)
Diffusing Species will Stay in Fractal when DF >1.0
Barbe, C., 2001 Australian Patent Application
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Connection to Biology
Enzyme Binding Surfaces Particles Better BioCatalysis
Protein Binding Surfaces Particles Better Implants
1/4th of Catalyase Tetramer
Liver Enzyme
2 H2O2 ----> 2 H2O + O2(g)
Heam Site
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Nano-particles for
Bio Separations/Bio Sensing
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Couple to Computation
Nanoparticle properties from Computational QM
Particulate Generation in CFDMolecular AdsorptionMolecular BindingFractals + Flow
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Conclusion
Particulate and Multiphase Program Bright Future
Many New Research Areas Many New Phenomena
Collaboration is key to SuccessVirtual Centers
• Nano Property Prediction• Photonic Crystals• Enzyme/Particle Binding• Fractal Aggregates• Nano Particle Synthesis
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New properties abound at this small scale
microscale nanoscale
Inertia
• Turbulence, convection, and momentum are negligible
• Surface and interfacial properties play dominant role
• Electronics, optics, mechanics, chemistry
• Atomic forces and chemical bonds dominate
Quantized effects “rule”
New knowledge and understanding is neededNew knowledge and understanding is needed
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Nanostructuring is Key to Novel/Enhanced Functionality
Layered-Structures Nanocrystals Nanocomposites
Electronics/photonics
Novel Magnets
Tailored hardness
Novel catalysts
Tailorable light emission
Supercapacitors
Separation membranes
Adaptive/responsive behavior
Pollutant/impurity gettering
Nanosciences will enable scientifically tailored materialsand lead to revolutionary advances in technology
Nanosciences will enable scientifically tailored materialsand lead to revolutionary advances in technology
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Layered and 3-D StructuresYield New Optical Properties
The VCSEL is to photonics what the transistor was to electronics. A key 21st century technology
Most efficient, low-power light source (57% in ‘97)
Applications in optical communications, scanners, laser printing, computing...
Vertical Cavity Surface Emitting Lasers (VCSELs)
Vertical Cavity Surface Emitting Lasers (VCSELs)Photonic LatticesPhotonic Lattices
Optical signals guided through narrow channels and around sharp corners
Near 100% transmission
Key technology for telecommunications and optical computing
A
2-D
B
3-D
poly-Si
Si substrate
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Water Condensation due to Shock Wave
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Deep Sea Life
Salt Lake Tribune, 2/13/97National Geographic October 2000
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Deep Sea Vents
C&E News 12/21/98National Geographic October 2000
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Deep Sea Vents
Deep Sea Vents Spew Solublized Salts into the cold sea, causing Precipitation & Crystalloluminescence
In the Deep Ocean Deep Sea Vents are the only source of Chemical Energy and Food
Mobile Animals need to be able to locate them - so they need eyes!!