1. Geetha R Dholakia NASA Ames Research Center
Applications of Nano Materials Relevance for Aerospace
Geetha R Dholakia NASA Ames Research Center
April 26, 2006
San Jose State University

2. 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.

3. Nanoscale objects and their properties
Nanoparticles
Nanotubes
Nanowires
Nanoscale films and coatings
Self assembled systems
Composites

4. NASA’s Requirements Ultrasmall sensors, power sources.
Low mass, volume and power systems.
For communication, navigation and propulsion.

5. NASA Nanotechnology Roadmap
Materials
Electronics/
computing
Sensors, Devices
Single-walled nanotube fibers
Low-Power CNT electronic components
In-space nanoprobes
Nanotube composites
Molecular computing/data storage
Nano flight system components
Integral thermal/shape control
Fault/radiation tolerant electronics
Quantum navigation sensors
Smart “skin” materials
Nano electronic “brain” for space exploration
Integrated nanosensors
Biomimetic material systems
Biological computing
NEMS flight systems
2002
2004
2006
2011
2016
>
Increasing levels of system design and integration
C A P A B I L I T Y
High Strength
Materials (>10 GPa)
Reusable Launch Vehicle (20% less mass, 20% less noise)
Revolutionary Aircraft Concepts (30% less mass, 20% less emission, 25% increased range)
Autonomous Spacecraft
(40% less mass)
Adaptive Self-Repairing Space Missions
Multi-Functional Materials
Bio-Inspired Materials
and Processes
Credits:NACNT

6. Energy Level Diagram: Quantum Size Effects
BULK
SEMICONDUCTOR
MOLECULE
NANOPARTICLE
LUMO CB
Energy Eg Eg Eg VB
HOMO

7. Eg of PbS nanoparticle vs particle size
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: Eg:0.41 eV eV.
(300K, 15 nm) (300K, 1.3 nm)
Eg of PbS nanoparticle vs particle size
Wang et al. J. Chem. Phys. 87, 12 (1987).

8. 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, (2004).

9. 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.

10. Applications of nanoparticles:Solar Cells
Spirit after two years
Conventional inorganic solar cells:
Efficiency ~ %.
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).

11. Carbon Nanotubes: Graphene Sheets to Nanotubes
Armchair
Chiral
Zigzag
d: 1.2 nm
From “Electronic Structure of Carbon Nanotubes” by L. C. Venema, Delft Univ. Press.

12. Carbon Nanotubes: Electronic Properties
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).

13. Eg of CNT vs tube diameter
Carbon Nanotubes: Energy gap of SWCNTs
Eg of CNT vs tube diameter
J. W. G. Wildoer et al., Nature, 391, 59 (1998).

14. Nanomaterials growth: VLS Growth of Nanowires
Example: Ge nanowire growth
Carrier Gas Flow
Ar + H2
480 ºC
1030 ºC
Source
Ge + C
Furnace Reactor
Substrate Si(111)
Au Catalyst
NW Growth
Vapor Phase Reactors + Carrier Gas
Au/Ge Liquid alloy

15. 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).

16. Applications of Nanotubes Nanoelectronic Devices: CNTs as FETs

17. Applications of Nanowires Nanoelectronic Devices: GaN Nanowires as FETs
Y. Huang et al., Nano Lett., 2, 101 (2002).

18. Applications of Nanotubes Photonic Devices: SWCNT IR emitter
J. A. Misewich et al., Science, 300, 783 (2003).

19. Applications of Nanowires Photonic Devices: p-si\n-GaN UV Nano LED
C. M. Lieber et al., Small, 1, 142 (2005).

20. 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.

21. Instrumentation: Nanotube Based Field Emitters
J. Robertson, Materials Today, 46 Oct 2004.
W. B. Choi et al., Appl. Phys. Lett, 75, 3129 (1999).

22. Chemical and Mineralogical Analysis
Instrumentation: Nanotube X Ray Tubes
Chemical and Mineralogical Analysis
Of Martian Rocks
PI Dr. D. Blake
NASA Ames

23. Other Aerospace Applications of Nanomaterials
Credits:NASA
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: o C.

24. 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.
Credits:JPL

25. Nanoroadmap: Technological and Economic Aspects

26. Thank you all.