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

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.

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

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

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

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

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 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).

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).

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.

Applications of nanoparticles:Solar 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/

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.

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

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).

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

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).

Applications of Nanotubes Nanoelectronic Devices: CNTs as FETs http://www.research.ibm.com/nanoscience/fet.html

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

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

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

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.

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

Chemical and Mineralogical Analysis 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/CheMin/

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: 200-1500o C.

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

Nanoroadmap: Technological and Economic Aspects http://www.nanoroadmap.it/roadmaps/NRM_Energy.pdf

Thank you all.