Geetha R Dholakia NASA Ames Research Center

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Geetha R DholakiaNASA Ames Research Center
Applications of Nano Materials Relevance for
Aerospace

• April 26, 2006
• San Jose State University

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Properties of Nanomaterials

• Changes in properties due to change in size
• Electronic properties, band gap etc.
• Material properties scaling due to size.
• Tensile strength, thermal conductivity etc.
• Higher order properties of nanostructures
• Self assembly, superlattices etc.

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Nanoscale objects and their properties

• Nanoparticles
• Nanotubes
• Nanowires
• Nanoscale films and coatings
• Self assembled systems
• Composites

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NASAs Requirements

• Ultrasmall sensors, power sources.
• Low mass, volume and power systems.
• For communication, navigation and propulsion.

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NASA Nanotechnology Roadmap
CreditsNACNT
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Energy Level Diagram Quantum Size Effects
BULK SEMICONDUCTOR
MOLECULE
NANOPARTICLE
LUMO
CB
Energy
Eg
Eg
Eg
VB
HOMO
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Nanoparticles Quantum Size Effects

• Quantum size effects
• Noble metals, Semiconductors, Oxides.
• Engineer Eg over a wide spectral range
• IR to UV.
• Semiconductor Q Dots
• II-VI CdS, CdTe, CdSe, PbS, ZnSe
• PbS Eg0.41 eV 2.34 eV.
• (300K, 15 nm) (300K, 1.3 nm)
  

Eg of PbS nanoparticle vs particle size
Wang et al. J. Chem. Phys. 87, 12 (1987).
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Nanoparticles Quantum Size Effects
CdSe quantum dots

• Semiconducting CdSe nanodots
• Illumination with a single light source
• Emission shifts to higher energy
• with decreasing particle size.
• Metallic Au nanodots
• Fluorescence shifts to longer ?
• (lower energy) with increasing nanocluster size.

J.L. West and N. Halas, Ann. Rev. BioMed. Eng. 5,
285 (2003).
Au Nanoclusters
J. Zheng et al, Phys. Rev. Lett. 93, 077402
(2004).
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Applications of nanoparticles Astronaut Health
and Biomedical Applications

Apollo 11 Mission
Imaging cells and drug delivery
B. Dubertret et al. Science, 298, 1759 (2002).

• Apollo 11 mission took 8 days 3 hrs and 18 min.
  July 16-24, 1969.
• Travel time to Mars 8 months one way.
• Astronauts will be exposed to effects of space
  radiation.
• Biocompatible Q Dots are used for diagnostic
  imaging of cells.
• Cancer cells can be targeted by adding antibodies
  to Q Dots which specifically bind to cancer cells.

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Applications of nanoparticlesSolar Cells
Spirit after two years

• Conventional inorganic solar cells
• Efficiency 10-30.
• Downside High fab cost.
• (high Ts, high vacuum, expensive litho.)
• Organic solar cells
• Low fab cost.
• Downside Efficiency 2 5
• Alternatives
• Hybrid dye sensitized Q dot and nanorod-polymer
  solar cells (TiO2, CdSe).

http//www.jpl.nasa.gov/missions/mer/
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Carbon Nanotubes Graphene Sheets to Nanotubes
d 1.2 nm
From Electronic Structure of Carbon Nanotubes
by L. C. Venema, Delft Univ. Press.
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Carbon Nanotubes Electronic Properties
P. G. Collins and Ph. Avouris, Scientific
American, 283, 62 (2000).
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Carbon Nanotubes Energy gap of SWCNTs
Eg of CNT vs tube diameter
J. W. G. Wildoer et al., Nature, 391, 59 (1998).
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Nanomaterials growth VLS Growth of Nanowires
Example Ge nanowire growth
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Nanowires Energy gap of Si Nanowires as a
function of diameter
Size Tunable Band Gap
D.D.D. Ma et al., Science, 299, 1874 (2003).
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Applications of Nanotubes
Nanoelectronic Devices CNTs as FETs
http//www.research.ibm.com/nanoscience/fet.html
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Applications of Nanowires
Nanoelectronic Devices GaN Nanowires as FETs
Y. Huang et al., Nano Lett., 2, 101 (2002).
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Applications of Nanotubes
Photonic Devices SWCNT IR emitter
J. A. Misewich et al., Science, 300, 783 (2003).
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Applications of Nanowires
Photonic Devices p-si\n-GaN UV Nano LED
C. M. Lieber et al., Small, 1, 142 (2005).
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NanoSensors and Detectors Nanotube Based Gas
Sensing
A. Modi et al., Nature, 424, 171 (2003).
Application Toxic gas detection and removal in
life support systems in space vehicles.
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Instrumentation Nanotube Based Field Emitters
J. Robertson, Materials Today, 46 Oct 2004.
W. B. Choi et al., Appl. Phys. Lett, 75, 3129
(1999).
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Instrumentation Nanotube X Ray Tubes
Chemical and Mineralogical Analysis Of Martian
Rocks
PI Dr. D. Blake NASA Ames
http//www.indiana.edu/geosci/research/mincm/CheM
in/
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Other Aerospace Applications of Nanomaterials
CreditsNASA

• Based on enhanced tensile strength, thermal
  conductivity and other nano material properties.
• Nanocomposites
• Self healing nanofiber, CNT, polymer, ceramic or
  metal matrix based composites.
• Lightwitght structures for spacecraft.
• Thermal protection systems and Radiation
  shielding.
• Entry temperatures 200-1500o C.

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Other Aerospace Applications of Nanomaterials

• Nanopowders for Solid-propellant rockets
• Aluminium or boron oxide nanopowders.
• Increased surface area of the nanopowders
  enhances thrust.
• Aerogels
• Thermal isolation material in the Mars Rover of
  the Pathfinder mission,
• Particle collector in the NASA Stardust mission.
• High strength, ultra-light structure materials
  for spacecraft.

CreditsJPL
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Nanoroadmap Technological and Economic Aspects
http//www.nanoroadmap.it/roadmaps/NRM_Energy.pdf
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Thank you all.