MatE297 Guest Lecture / GR Dholakia Geetha R Dholakia NASA Ames Research Center April 26, 2006 San...
-
Upload
peter-stewart -
Category
Documents
-
view
220 -
download
1
Transcript of MatE297 Guest Lecture / GR Dholakia Geetha R Dholakia NASA Ames Research Center April 26, 2006 San...
MatE297 Guest Lecture / GR Dholakia
Geetha R Dholakia
NASA Ames Research Center
April 26, 2006
San Jose State University
Applications of Nano Materials Relevance for Aerospace
MatE297 Guest Lecture / GR Dholakia
• 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.
Properties of Nanomaterials
MatE297 Guest Lecture / GR Dholakia
Nanoscale objects and their properties
• Nanoparticles
• Nanotubes
• Nanowires
• Nanoscale films and coatings
• Self assembled systems
• Composites
MatE297 Guest Lecture / GR Dholakia
NASA’s Requirements
• Ultrasmall sensors, power sources.
• Low mass, volume and power systems.
• For communication, navigation and propulsion.
MatE297 Guest Lecture / GR Dholakia
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 StrengthMaterials (>10 GPa)
High StrengthMaterials (>10 GPa)
Reusable Launch Vehicle (20% less mass, 20% less noise)
Reusable Launch Vehicle (20% less mass, 20% less noise)
Revolutionary Aircraft Concepts (30% less mass, 20% less emission, 25% increased range)
Revolutionary Aircraft Concepts (30% less mass, 20% less emission, 25% increased range)
Autonomous Spacecraft (40% less mass)
Autonomous Spacecraft (40% less mass)
Adaptive Self-Repairing Space Missions
Adaptive Self-Repairing Space Missions
Multi-Functional MaterialsMulti-Functional Materials
Bio-Inspired Materialsand ProcessesBio-Inspired Materialsand Processes
Credits:NACNT
MatE297 Guest Lecture / GR Dholakia
MOLECULE
LUMO
HOMO
CB
VB
Eg
Ene
rgy
NANOPARTICLE
Eg Eg
BULKSEMICONDUCTOR
Energy Level Diagram: Quantum Size Effects
MatE297 Guest Lecture / GR Dholakia
• 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 2.34 eV.
(300K, 15 nm) (300K, 1.3 nm)
Eg of PbS nanoparticle vs particle size
Nanoparticles: Quantum Size Effects
Wang et al. J. Chem. Phys. 87, 12 (1987).
MatE297 Guest Lecture / GR Dholakia
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. Zheng et al, Phys. Rev. Lett. 93, 077402 (2004).
J.L. West and N. Halas, Ann. Rev. BioMed. Eng. 5, 285 (2003).
Nanoparticles: Quantum Size Effects
Au Nanoclusters
MatE297 Guest Lecture / GR Dholakia
Applications of nanoparticles: Astronaut Health and Biomedical Applications
• 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.
B. Dubertret et al. Science, 298, 1759 (2002).
Apollo 11 Mission
Imaging cells and drug delivery
MatE297 Guest Lecture / GR Dholakia
Applications of nanoparticles:Solar Cells
• 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/
Spirit after two years
MatE297 Guest Lecture / GR Dholakia
Carbon Nanotubes: Graphene Sheets to Nanotubes
Armchair
Chiral
Zigzagd: 1.2 nm
From “Electronic Structure of Carbon Nanotubes” by L. C. Venema, Delft Univ. Press.
MatE297 Guest Lecture / GR Dholakia
P. G. Collins and Ph. Avouris, Scientific American, 283, 62 (2000).
Carbon Nanotubes: Electronic Properties
MatE297 Guest Lecture / GR Dholakia
Carbon Nanotubes: Energy gap of SWCNTs
J. W. G. Wildoer et al., Nature, 391, 59 (1998).
Eg of CNT vs tube diameter
MatE297 Guest Lecture / GR Dholakia
Carrier Gas Flow
Ar + H2
480 ºC1030 ºCSourceGe + C
Furnace Reactor
Substrate Si(111)
Au Catalyst
NW Growth
Vapor Phase Reactors + Carrier Gas
Au/Ge Liquid alloy
Nanomaterials growth: VLS Growth of Nanowires
Example: Ge nanowire growth
MatE297 Guest Lecture / GR Dholakia
D.D.D. Ma et al., Science, 299, 1874 (2003).
Nanowires: Energy gap of Si Nanowires as a function of diameter
Size Tunable Band Gap
MatE297 Guest Lecture / GR Dholakia
Applications of Nanotubes Nanoelectronic Devices: CNTs as FETs
http://www.research.ibm.com/nanoscience/fet.html
MatE297 Guest Lecture / GR Dholakia
Y. Huang et al., Nano Lett., 2, 101 (2002).
Applications of Nanowires Nanoelectronic Devices: GaN Nanowires as FETs
MatE297 Guest Lecture / GR Dholakia
J. A. Misewich et al., Science, 300, 783 (2003).
Applications of Nanotubes Photonic Devices: SWCNT IR emitter
MatE297 Guest Lecture / GR Dholakia
Applications of Nanowires Photonic Devices: p-si\n-GaN UV Nano LED
C. M. Lieber et al., Small, 1, 142 (2005).
MatE297 Guest Lecture / GR Dholakia
A. Modi et al., Nature, 424, 171 (2003).
NanoSensors and Detectors: Nanotube Based Gas Sensing
Application:
Toxic gas detection and removal in life support systems in space vehicles.
MatE297 Guest Lecture / GR Dholakia
J. Robertson, Materials Today, 46 Oct 2004.
Instrumentation: Nanotube Based Field Emitters
W. B. Choi et al., Appl. Phys. Lett, 75, 3129 (1999).
MatE297 Guest Lecture / GR Dholakia
Instrumentation: Nanotube X Ray Tubes
Chemical and Mineralogical Analysis
Of Martian Rocks
http://www.indiana.edu/~geosci/research/mincm/CheMin/
PI Dr. D. Blake
NASA Ames
MatE297 Guest Lecture / GR Dholakia
Other Aerospace Applications of Nanomaterials
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.
Credits:NASA
MatE297 Guest Lecture / GR Dholakia
• 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.
Other Aerospace Applications of Nanomaterials
Credits:JPL
MatE297 Guest Lecture / GR Dholakia
http://www.nanoroadmap.it/roadmaps/NRM_Energy.pdf
Nanoroadmap: Technological and Economic Aspects