Argonne National Laboratory Center for Nanoscale Materials U.S. Department of Energy

Archive: Seminars 2001-2003

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Dec. 4, 2003

"New Optics with Negative Refraction," Dr. David Smith, University of California San Diego

Abstract: The possibility of negative refraction, first hypothesized by Victor Veselago in 1968, has brought about a reconsideration of many fundamental optical and electromagnetic phenomena. This new degree of freedom has provided a tremendous stimulus for the physics, optics, and engineering communities to investigate how this new material parameter space can be utilized. Many interesting and potentially important effects not possible in positive refracting materials, such as near-field refocusing and sub-diffraction limited imaging, have been predicted to occur when the refractive index changes sign. In this talk, I will review our own work on negative refraction in isotropic and anisotropic media and describe the possible impact of these materials as new types of optical elements. I will also describe some of the recent work from our collaborators and other researchers.

Oct. 10, 2003

"Design and Control of the Superparamagnetic Properties of Cobalt-Based Ferrite Nanoparticles," by Dr. Anna Cristina S. Samia, Department of Chemistry, Case Western Reserve University, hosted by Xiao-Min Lin

Abstract: Over the last few years, interest in nanosized magnetic particles has grown enormously due to their wide ranging applications. Magnetic nanoparticles themselves are used as the active component of ferrofluids, disk recording media, as well as biomedical materials and catalysts. Each application demands unique magnetic characteristics of nanoparticles. Hence, the ability to tailor them into the desired properties is of considerable importance. In optimizing the applicability of these unique materials, understanding and controlling of their superparamagnetic properties is vital. In this presentation the design and control of the superparamagnetic properties of cobalt ferrite nanoparticles is presented. By utilizing a chemometric model, which provides a quantitative correlation between preparative conditions with nanoparticle size, it was possible to systematically produce a series of nanoparticle sizes that facilitated the investigation of the size effect on the superparamagnetic properties of the cobalt ferrite nanoparticles. A next step is the chemical control of the superparamagnetic properties of cobalt ferrite nanoparticles by means of metal ion substitution. To add another means of tuning the superparamagnetic properties of these materials, a new type of core-shell ferrite nanoparticle was synthesized that exploits the magnetic couplings between the different layers.

Oct. 3, 2003

“Nanometer Structures Produced on High Index SI Surfaces” by Alison Baski, Virginia Commonwealth University, Richmond

Sept. 11, 2003

"Engineering Surfaces for Directed Motion of Motor Proteins: Building a Nanoscale Shuttle System," Dr. John Clemmens, Bioengineering and Nanotechnology, University of Washington, hosted by Dr. Darrell P. Chandler, Biodetection Technology Section, Energy Systems Division

August 4, 2003

"'Soft' Materials and Patterning Techniques for Electronics, " Prof. John A. Rogers, University of Illinois at Urbana-Champaign, Dept. of Materials Science & Engineering

Abstract: Organic and molecular materials may play key roles in new, emerging areas of electronics, photonics and nanotechnology. Additive printing and lamination techniques can be used directly with these classes of 'soft' materials to build unusual devices with dimensions deep into the nanometer regime. This talk describes these methods and illustrates their use in fabricating organic transistors and circuits, light emitting diodes, and prototype systems, such as electronic paperlike displays, that demonstrate some potential applications.

August 6, 2003

"Micromagnetics at the Nanoscale," E. Dan Dahlberg, Magnetic Microscopy Center, School of Physics and Astronomy, University of Minnesota

Abstract: In the area of micromagnetics, major breakthroughs have resulted from the development of new imaging techniques. A powerful magnetic microscope is the magnetic force microscope (MFM), a variant of the atomic force microscope. One of the frontiers in magnetism being pushed back is to understand the domain structure and the magnetization reversal in nanometer-sized particles. We have combined high-resolution MFM (30 nm) with Landau Lifschitz Gilbert simulations to investigate the magnetic domain structure in nickel dots with diameters ranging from 40 to 1700 nm. The nickel dots were prepared with a perpendicular anisotropy energy. In unpatterned films, the perpendicular anisotropy induced stripe domains with a period on the order of 200 nm. The statistics of the allowed states in the dots was determined by using the MFM data from more than 3000 images. Ccomparison of the MFM images with the LLG simulations provides confidence that the magnetic structure beyond the MFM resolution is accurate.

August 6, 2003

"Nanostructures: Top down meets bottom up," Henry I. Smith, Keithley Professor of Electrical Engineering, Massachusetts Institute of Technology

Abstract: In lithography-based planar processing, one converts a concept into a fine-scale two-dimensional template impressed into a substrate. The function that results depends on the geometry of the template. The applications of the planar process in modern electronics are well known. However, the concept of deriving function from structure is very general; its importance and applications extend well beyond electronics. The role of lithography-based planar processing in nanoscale science and engineering will be explored, with emphasis on seeking a bridge between “top down” and “bottom up” approaches to nanoscale engineering. Recent research in templated self assembly will be described along with efforts to develop advanced lithography techniques that achieve nanometer-level accuracy.

June 6, 2003

"Metal Oxide Nanoparticles as Carriers of Active Molecules. Bactericidal, Sporicidal, and Antitoxin Activity," Peter K Stoimenov, Department of Chemistry, Kansas State, hosted by Xiao-Min Lin

Abstract: The chemical reactivity of solid materials is determined exclusively by their surface. The rate of practically all chemical reactions involving solid substances is dependent on parameters such as surface area, number of active sites (usually higher energy sites such as corners and edges), the type of surface plane exposed to the reactant, etc. When any material is broken down to nanoscale dimensions, these parameters are dramatically altered, thus causing remarkable change in the chemical behavior, although the chemical composition is essentially the same. In the present study, very high surface area MgO nanoparticles (500 >m2/g and above) are prepared by an aerogel method. High-resolution Transmission Electron Microscopy (HRTEM) of the nanoparticulate samples reveals particles with an average size of 4 nm and presence of multiple edges and corners in an extensive porous framework. These nanoparticles exhibit significantly enhanced adsorption activity of variety of molecules compared to the commercially available MgO. A procedure was developed for the reversible adsorption of halogen molecules such as chlorine, bromine and iodine and of interhalogen compounds such as iodine monochloride, iodine monobromide and iodine trichloride. Such formulations are interesting from both theoretical and practical points of view. Raman spectroscopy and TGA were used to elucidate the structure of the adducts and their composition.

The unique ability of MgO nanoparticles to adsorb large amounts of halogens and interhalogens makes them excellent candidates as potential bactericidal and antitoxin agents. The bactericidal and sporicidal activity was tested against mimics of biological warfare agents such as E. Coli, B. subtilis spores, and algae toxins (microcystins). The nanoparticulate adducts were found to have excellent biocidal activity against a variety of microorganisms. The mechanism of action was studied in details by Atomic Force Microscopy (AFM), TEM, confocal microscopy and z-potential measurements. The most important factors for the bactericidal action were found to be the abrasiveness of the nanoparticles, their basic character as well as the electrostatic attraction with the cells complemented by the oxidation power of the halogen loaded on the particles. Bromine loaded oxide nanoparticles were found to be very successful in detoxification of microcystins. The mechanism of action was investigated by enzyme inhibition assay and MALDI mass spectrometry.

May 29, 2003

"Molecular Recognition and Self-Assembly With a Versatile Molecular Receptor," Andrew Goshe, University of Chicago, Department of Chemistry, hosted by David Tiede

Abstract: Molecular receptors, consisting of two cofacially disposed terpyridyl-metal-ligand units separated by ~7Å were designed and >synthesized. The molecular receptors were found to be competent hosts for selected organic molecules as well as a variety of Pd(II) and Pt(II) complexes. Solution binding studies determined the structure and strength of the interactions. The molecular receptors were also used to generate large, symmetric structures by self-assembly at the metal ligand bond. These structures were capable of binding multiple guest molecules. Self-assembly by the deployment of weak forces was also probed with these systems.

April 24, 2003

"Nanocrystal Superlattices Composed of Gold Nanoparticles," Savka I. Stoeva, Department of Chemistry, Kansas State University, hosted by Xiao-Min Lin

Abstract: Monodisperse gold nanoparticles have been prepared by solution and vapor phase methods. The synthesis in solution utilizes the reduction of gold salts in inverse micelle media. The vapor phase method is based on the Solvated Metal Atom Dispersion technique (SMAD). SMAD employs a codeposition of metal and organic solvent on the walls of a reactor cooled to liquid nitrogen temperature. Both preparative methods result in high-quality nanoparticles stabilized by ligands with different chain length. Gold nanoparticles prepared by both techniques have a strong propensity towards nanocrystal superlattice formation. Dodecanethiol stabilized gold nanoparticles with similar average size organize into different superlattice structures depending upon the method of preparation of the nanocrystals. Particles synthesized by the inverse micelle technique preferentially assemble into face-centered cubic (fcc) structures with long-range translational and orientational ordering. Gold nanoparticles obtained by the Solvated Metal Atom Dispersion method (SMAD) behave like 'hard' spheres and predominantly organize into hexagonal-close packed (hcp) nanocrystal superlattices with long-range translational ordering. Different packing behavior results from differences in nanoparticles core morphologies induced by the synthetic method; fcc ordering is preferred by single crystalline, while hcp is preferred by polycrystalline nanoparticles. A combination of optical, transmission electron microscopy (TEM and HRTEM), selected area electron diffraction (SAED), atomic force microscopy (AFM) and X-ray diffraction (XRD) were used to characterize both the dispersed nanoparticles and the nanocrystal superlattices.

April 18, 2003

"Solid-State Metathesis as a Rapid Synthetic Route to AlN and TiN," Rebecca Janes, Department of Chemistry and Biochemistry, UCLA, hosted by David Tiede

Abstract: Metathesis (exchange) reactions are driven by the formation of stable salt by-products, which are easily washed away after reaction completion. Upon initiation of the precursor salts, intense heat (generally 1000°C) is very rapidly generated (often < 1 sec) and then quickly dissipated. Many metal nitrides are useful materials, such as aluminum nitride, AlN, which is used for substrates for semiconductors due to its high resistivity, low dielectric constant, and a coefficient of thermal expansion matched to silicon, and titanium nitride, TiN, which is widely used in hardness coatings. Here a metathesis reaction between AlCl3 and Ca3N2 produces AlN in seconds. A temperature of greater than 1700°C is reached in less than one second as measured using an in situ thermocouple. TiN is made from the reaction between TiCl3 and Ca3N2 which reached over 1300°C. Crystallite size and surface area can be controlled using salt additives. Characterization using XRD, SEM, TEM and BET will be presented.

April 9, 2003

"Near-Field Magneto-Photoluminescence and Optical-Fiber-Induced Stress Experiments on Quantum Dots in III-V Semiconductor Compounds, " James L. Merz, Frank M. Freimann Prof. of Engineering, Department of Electrical Engineering, University of Notre Dame, hosted by Gary Wiederrecht (abstract)

April 8, 2003

"Nanoscale Manganese Oxide Octahedral Molecular Sieves: Synthesis, Characterization, and Applications, " Jia Liu, Institute of Materials Science, University of Connecticut, hosted by David Tiede

Abstract: Different novel synthetic routes have been investigated to >find better, faster, and cheaper paths for producing nanoscale manganese oxide octahedral molecular sieve (OMS) materials. A combined sol-gel synthesis and hydrothermal reaction was developed to prepare pure crystalline todorokite-type (OMS-1) and cryptomelane-type (OMS-2) manganese oxides nanomaterials. These nanoscale materials have been characterized using a variety of techniques, such as TEM, XRD, SEM, TGA, TPD-MS, ICP-AES, etc. The crystal growth mechanism, structures, and preparative parameters of syntheses (i.e. cation templates, heating temperature and time) have been investigated for these nanoscale OMS materials. Mg-OMS-1 nanoribbons with a long-range ordered tunnel structure has been successfully prepared for the first time. Three alkali cations (Li+, K+, Na+, Rb+) and NH4+ cations have been systematically used to prepare nanofibrous OMS-2 materials. Li- and Rb-OMS-2 were synthesized for the first time. The effects of tunnel cations on the physical and chemical properties have been studied. The catalytic activities of the novel synthetic OMS nanomaterials have been evaluated in the aerobic oxidation of alcohols, and were found being dramatically improved over the activities of conventional OMS bulk materials.

April 2, 2003

"Development of Molecularly Imprinted Polymers (MIPs) for the Selective Recognition of Biomolecules," Dolly Batra, Department of Chemistry, University of California, Irvine, hosted by Millicent Firestone

Mar. 21, 2003

"Experiments with Mossbauer Diffraction in 57Fe," Ushma Kriplani, hosted by Gary Wiederrecht

Abstract: This talk describes the design and construction of a highly sensitive, automated instrument used to perform Mossbauer diffraction experiments, and recent results obtained on 57Fe. Mossbauer diffraction is a novel technique for characterizing the structure of materials, which utilizes the response of nuclear energy levels to the chemical environment of the atom. In addition, the scattering process in the material depends on the interaction between the polarization of the g-rays and the hyperfine field of the nucleus, and this was studied for the first time by applying an external magnetic field to the 57Fe sample, which aligns the nuclear hyperfine fields while leaving the hyperfine field strength largely unaffected, and differentially affects horizontally and vertically polarized photons. The diffractometer consists of a wire chamber detector, a motorized goniometer, a Doppler drive modified for computer control and a detector synchronization circuit implemented in programmable logic. A comprehensive model was developed to describe the scattering processes undergone by the g-rays in the sample.

Feb. 25, 2003

"Spin-dependent transport through point-contacts, " Yi Ji, Johns Hopkins University

Abstract: Point-contact spectroscopy technique has been used to study (1) the spin polarization of ordinary and half-metallic ferromagnets (2) spin-transfer torques in a single ferromagnetic layer.

Ferromagnetic materials with substantial spin polarization play a crucial role in spintronic devices such as MRAM. Of particular interest is half-metallic ferromagnet with 100% spin polarization. The values of spin polarization of a ferromagnet can be reliably determined using point-contact Andreev reflection (PCAR) with proper quantitative analysis. We have measured the spin polarizations of common ferromagnets iron, cobalt, and nickel, as well as single crystals of La0.7Sr0.3MnO3 and CrO2. Most importantly, we demonstrated CrO2 is indeed half-metallic with a polarization no less than 96%.

It is known that the magnetic configuration of a ferromagnetic/non-magnetic multilayer affects its electrical properties, an effect called GMR. Spin-transfer torque is the reverse effect. A spin-polarized electrical current flowing perpendicularly through a multilayer can alter its magnetic configuration. The underlying physics is that spin-polarized carriers transfer spin angular momentum onto the magnetizations and thereby imparting a torque. While ferromagnetic/non-magnetic multilayers were generally considered indispensable to this effect, we have demonstrated spin-transfer torques in a single ferromagnetic layer.

Feb. 17, 2003

"Magnetism and Self-Assembly of Shape-Controlled Cobalt Nanocrystals and Their Superlattices," Prof. Kannan Krishna

Abstract: Size-dependent scaling laws and the magnetic behavior of small particles and nanostructured assemblies, as a function of size, shape, dimensionality and inter-particle interactions are increasingly of fundamental and technological interest. In this talk, I will present

  • Details of the chemical synthesis of mono-disperse, metallic, passivated cobalt nanocrystals with good size/shape control
  • Recent results on controlled self-assembled arrays obtained from this single component nanocrystals system by a systematic variation of their size, shape and inter-particle interactions. The self-assembled arrays can be tuned to selectively achieve square packing, hexagonal close packing, linear chains, spatially segregated arrays as a function of particle size and lyotropic liquid-crystal-like arrays with orientation order. This richness in self-assembly is obtained when one of a set of competing forces (steric, van der Waals, depletion, or magnetostatic) are chosen to dominate and determine the resulting organization.
  • Preliminary high-resolution electron holography measurements to elucidate the magnetostatic coupling between the nanocrystals.
  • SQUID magnetometry data including zero-field cooled, field-cooled, thermomagnetic remanence and memory measurements.

Nov. 26, 2002

  • "Large Area Plasma Sprayed Electrodes for Batteries and Fuel Cells," David E. Reisner, Ph.D., U.S. Nanocorp and Inframat
  • "Ceramic Nanocoatings and Magnetic Nanocomposites Research at Inframat," Paul E.C. Bryant, Inframat.

August 8, 2002

  • "Operational Aspects of a University, Microelectronics Cleanroom" (348kb pdf)
  • "Design of a University, Microelectronics Cleanroom" (506kb pdf)

Presented Daniel Christensen, Laboratory Manager of the Wisconsin Center for Applied Microelectronics at the University of Wisconsin-Madison, hosted by John Sidarous

March 22, 2002

"Understanding the Patterning Limitations of Electron Beam Nanolithography,: Dr. Leo Ocola, Agere Systems, Advanced Lithography Research, Murray Hill, NJ, hosted by Derrick Mancini (Abstract, 12kb pdf)

March 28, 2002

"Phonon in Quantum Confined Geometries," Prof. Michael Stroscio, University of Illinois at Chicago, Department of BioEngineering, Department of Electrical and Computer Engineering, hosted by Derrick Mancini (Abstract, 13kb pdf)

March 28-30, 2002

Oct. 9, 2001

Nanoscale Science Using Synchrotron Techniques (Abstracts, 488kb pdf)

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