GRD MatE

Geetha R DholakiaNASA Ames Research Center: 

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

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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

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

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

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NASA Nanotechnology Roadmap Credits:NACNT

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

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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).

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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

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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

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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

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

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

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Nanomaterials growth: VLS Growth of Nanowires Example: Ge nanowire growth

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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

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

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

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

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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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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.

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J. Robertson, Materials Today, 46 Oct 2004. Instrumentation: Nanotube Based Field Emitters 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 http://www.indiana.edu/~geosci/research/mincm/CheMin/ PI Dr. D. Blake NASA Ames

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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

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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

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

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Thank you all.