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

A guest editorial from a new member of the CNM staff

Andreas RoelofsI would like to take a moment to introduce myself as the new Deputy Division Director for the Center of Nanoscale Materials. I feel very fortunate to have been given the opportunity to work with the staff at the CNM as well as with our current and future users. Let me also take this opportunity to thank everyone for the great welcome I have received. In return, you will always find my door open, and you can feel free to come to me with any questions or concerns. I am very much looking forward to our future interactions.

My research interests are focused on ferroic thin films, oxide nanograins, and scanning probe microscopy techniques. More specifically, my expertise is in ferroelectric thin films and their electrical and electromechanical characterization. Other areas of interest are the development of micro-electromechanical systems (MEMS) actuated by piezoelectric thin films (piezo-MEMS) and alternative memory materials and concepts. Prior to joining the CNM, I worked in industry in the areas of materials research and solid-state memory development.

My initial CNM experience had been as a user, and I enjoyed my time here very much. One of my tasks as deputy director will be to increase the Center's visibility to other researchers in industry in order to attract more of them as users. I believe the CNM will greatly benefit from increasing the number of industrial users, which will further diversify an outstanding user base and will lead to exciting new discoveries in nanoscience and nanotechnology.

Andreas Roelofs
CNM Deputy Division Director

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Call for Proposals Deadline: October 28, 2011

The system is now open for submissions. We look forward to the possibility of hosting your exciting and innovative nanoscience and nanotechnology projects.(More >>)

CNM Users Meeting, May 7-10, 2012
Save the Date!

The next Argonne APS/CNM/EMC Users Meeting will be held May 7-10, 2012. More than 500 people registered for the inaugural cross-cutting meeting in 2011 along with 45 vendor exhibits, and a similar turnout is expected for the 2012 meeting. Planning is already under way to develop thematic and facility-specific workshops that will highlight, promote, and stimulate user science from these three user facilities. Your suggestions for thematic and CNM workshop topics are welcome; please send them to the User Office.

CNM Announces Maintenance Shutdown Periods

To better ensure reliable instrument availability, the CNM will announce defined maintenance periods three times per calendar year beginning in 2012. During these times, the CNM will not be available for onsite user activities. These maintenance periods, lasting a maximum of one week each, will be used to perform preventive maintenance on the scientific instruments and their support equipment. In addition, the facility's operating infrastructure systems will undergo preventive maintenance that will help avoid unplanned shutdowns.

The maintenance periods will occur at these times:

  • First week in January following the December holiday break
  • Last week in May before the Memorial Holiday break
  • First week in September following the Labor Day Holiday break

Note: The CNM will continue to close on additional dates, such as for annual holiday periods.

Changes to User Training Course Requirements

As of October 1, 2011, CNM users are no longer required to take Argonne's ESH377 awareness course for electrical safety training. The relevant general electrical safety information for CNM users has been added to ESH100U (which now has a new two-year training interval).

As a user, the only electrical-related activities you are permitted to perform at Argonne are:

  • Plug into and unplug from an outlet a piece of electrical equipment, with a plug that easily fits the receptacle and requires no modifications, that has either a NRTL marking such as from Underwriters Laboratories Inc. (UL), or has an Argonne Designated Electrical Equipment Inspector (DEEI) approval sticker.
  • Operate/use such a piece of equipment in accordance with its instructions.
  • Operate common light switches.
  • Replace batteries in common consumer-type products such as tools, pagers, cell phones, and laptop computers.

Contact your Scientific Contact if any other electrical-related work, task, or activity is required.

User Notes

Acknowledgment of the use of DOE user facilities in scientific publications and technical presentations is vital for their future sustainability. An acknowledgment statement must be included in all published reports of work conducted at the Center for Nanoscale Materials. (Review the guidance.)

We are excited to chronicle the scientific advancements of CNM's users by your user activity reports. Since time is becoming more competitive, completion of reports on past projects is now required for consideration of new proposals.

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Structural Consequences of Nanolithography

Structural effects accompanying the nanoscale lithography of ferroelectric polarization domains have been mapped by users from the University of Wisconsin-Madison and the Center for Nanophase Materials Science, working with CNM's X-Ray Microscopy Group. The results shed new light on the physics of structural changes induced during this model nanoscale lithographic process. X-ray nanodiffraction microscopy performed at the Hard X-Ray Nanoprobe beamline was used to probe a pattern that was written into a PZT ferroelectric layer by using scanning-probe ferroelectric nanolithography. This adaptation of piezoresponse force microscopy (PFM) can be used to write arbitrary nanoscale domain patterns into a ferroelectric thin film. This approach allows for control of nanoscale degrees of freedom with scanning probes.

J. Y. Jo et al., Nano Lett., 1, (1), 3080-3084 (2011). DOI: 10.1021/nl2009873

X-ray diffraction patterns

X-ray nanodiffraction pattern acquired at 11.75 keV from a written domain of PZT. The 2θ angle of the maximum intensity (dashed line) is higher in the domains written by PFM.

Crystals under Stress: Symmetry Survives Structural Transition

Discovery of a symmetry-preserving (isosymmetric) structural transition hidden in materials with polyhedral frameworks encourages closer studies of epitaxially grown perovskite oxide films. Using first-principles calculations on the CNM’s high-performance supercomputing cluster (Carbon), users from Argonne National Laboratory, Drexel University, and Rutgers University predict that this latent transition occurs between two crystalline phases with corner-connected octahedra grown in thin-film form. The transition emerges only under application of two-dimensional (biaxial) stress applied by a substrate. While most perovskites exhibit transitions involving changes in crystallographic symmetry due to pressure or temperature, this peculiar transition lacks that feature. Since most technologically used phase-change materials lose symmetry upon switching, studies of these rare transitions could dramatically redefine integrated material performance.

J. M. Rondinelli and S. Coh, Phys. Rev. Lett., 106, 235502 (2011)

Crystals under Stress

The transition is discernible by monitoring the change in rotation of adjacent octahedral units forming the LaGaO3 framework. The rotation axis completely reorients with changes in the elastic strain imposed by the substrate.

SERS Probe of Molecular Interactions at Semiconducting Nanoparticle Surfaces

The behavior of catechol derivatives adsorbed on TiO2 nanoparticles in solution was investigated by users from Northwestern University working with the CNM NanoBio Interfaces Group. A SERS Raman signal changed as a function of dopamine coverage and when metal ions were added to catechol derivatives with extended conjugation. A theoretical model was developed to explain the dependence in terms of competing kinetics involving a low-density electron gas that is formed by the injection of electrons in the semiconductor's conduction band. In addition, the Raman signal intensities and their dependence on nanoparticle size and solvent were calculated. Understanding how the charge-transfer state in bio-inorganic systems can be coupled to the outside environment (solvent, metal ions, functional groups, peptides) can have important technological applications in the sensor area and for solar fuels.

D. Finkelstein-Shapiro, P. Tarakeshwar, T. Rajh, and V.J. Mujica, Phys. Chem. B., 114, 14642 (2011)

Raman values and theoretical fit for electron gas from a nanoparticle complex

Experimental Raman values (dots) and theoretical fit (line) for the electron gas from a 2-nm dopamine/TiO2 nanoparticle complex

size dependence

The size dependence on the HOMO and LUMO of dopamine/TiO2 CT complexes was modeled (LUMO shown here).

Toward Gas Sensors Using Reduced Graphene Oxide

Several functional gas sensors have been fabricated by users from the University of Wisconsin at Milwaukee, working with the CNM Nanofabrication & Devices Group, by using SnO2 nanocrystals (NCs), SnO2 NC-coated carbon nanotubes (CNTs), and reduced graphene oxide sheets (RGO). Hybrid SnO2 NC-CNT structures exhibit high sensitivity to low-concentration gases at room temperature. The hybrid platform provides a new opportunity to engineer sensing devices with quantum-mechanical attributes by taking advantage of the electronic transfer between the NCs and the CNTs. A signal processing method also was proposed to address variations for room-temperature sensing devices using graphene and CNTs, paving a way to practical utilization of these novel materials for sensing applications.

G. Lu et al., ACS Nano, 5, 1154 (2011)

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RGO device schematic

Schematic of the reduced graphene oxide RGO device with an FET platform.

SEM of proposed sensing device

SEM image of a sensing device composed of RGO platelets bridging neighbor Au fingers.

NanoLog Spectrofluorimeter

The recently installed NanoLog spectrofluorimeter from Horiba Jobin Yvon provides extensive capabilities within the Nanophotonics Group to characterize luminescence at ultraviolet, visible, and near-infrared wavelengths, providing key information about the properties of light-emitting nanomaterials. The system can rapidly acquire two-dimensional maps of emission intensity as a function of both excitation and emission wavelength, providing critical information about photophysical processes such as energy relaxation and charge trapping in semiconductor nanocrystals, about the distribution of diameters and chiralities in a sample of carbon nanotubes, and about energy-transfer and charge-transfer processes in hybrid nanomaterials. Emission in the visible range can also be resolved as a function of time using time-correlated single-photon counting, enabling the determination of electron-hole recombination rates in nanocrystals or electronic relaxation rates in molecules. Liquid, solid, and powder samples can all be measured, and a recirculating bath allows temperature control of liquid samples. An integrating-sphere accessory to be installed shortly will allow for calibrated measurement of all the light emitted from a sample; this will enable, for example, absolute measurements of photoluminescence quantum yields from solid samples.

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Photolumniscence decay of nanorods

Photoluminescence decay of CdSe/CdS nanorods monitored at different wavelengths

Excitation and emission spectra of nanorods

Contour plot showing excitation and emission spectra of CdSe/CdS nanorods

 
Saw Wai Hla

Saw Wai Hla has joined the CNM as Group Leader of the Electronic & Magnetic Materials & Devices Group. Saw comes to us from Ohio University, where he will continue 25% as a full professor in the Physics and Astronomy Department. Saw's research includes low-temperature scanning tunneling microscopy, tunneling spectroscopy, spin-polarized scanning tunneling microscopy, and manipulation of single atoms and molecules as well as single-molecule studies of molecular spintronics, molecular magnetism, molecular electronics, molecular machines, and molecular switches and devices. Saw previously served two terms on the CNM Proposal Evaluation Board.

Orlando Auciello and Anirudha Sumant

 

An R&D 100 Award for 2011 involved two staff members from the CNM Nanofabrication & Devices Group: Orlando Auciello (CNM and Argonne's Materials Science Division) and Anirudha Sumant, along with several industrial partners. The invention was titled, "The Integrated Radio Frequency (RF) Microelectromechanical System (MEMS) Switch/ Complementary Metal-Oxide Semiconductor (CMOS) Device."  Monolithically integrated RF-UNCD (ultrananocrystalline diamond) MEMS switch/CMOS devices will enable the next generation of communications devices to more seamlessly handle data, voice, audio, and video simultaneously while supporting multiple RF systems operating in several different frequency bands ranging from megahertz to gigahertz. (More >>)

Elena Rozhkova

Elena Rozhkova of the NanoBio Interfaces Group provided the keynote address on "Multifunctional Materials for Nanomedicine" at the Fourth Annual Nanotechnology Symposium held at the Sullivan University College of Pharmacy in Louisville, KY, September 23-34, 2011. Elena also recently wrote an invited progress report article for the new Advanced Healthcare Materials section of the high-impact journal Advanced Materials (23, H136, 2011). The focus of this article was on different aspects of the materials science behind clinical diagnosis and treatment.

Liliana Stan

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Liliana Stan, who came to us from Los Alamos National Laboratory, joined the CNM Nanofabrication & Devices Group where she is contributing to the design, synthesis, and characterization of multilayered thin-film structures. Her expertise includes physical vapor deposition techniques, such as sputtering, ion-beam-assisted deposition (IBAD), and electron-beam evaporation, and characterization of metal-oxide films and multifunctional nanocomposites. She has worked on understanding the processing-microstructure-property relationships of multilayered heteroepitaxial structures and the development of biaxially oriented thin films grown on amorphous substrates using IBAD.

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