**Research Activity: Physical Behavior of Materials**

Division: Materials Sciences and Engineering

Primary Contact: Refik Kortan
(Refik.Kortan[\@science.doe.gov](mailto:Yok.Chen@science.doe.gov);
301-903-3427)

Team Leader: Helen Kerch (Acting)

Division Director: Harriet Kung

**Portfolio Description:**

This activity is a fundamental research program focusing on the
functional properties of materials. The major emphasis is on the
behavior of complex materials in response to external stimuli often
encountered in energy-intensive applications. This basic research
program focuses on physical responses (such as optical, electronic, or
magnetic changes) to temperature, electro-magnetic fields, chemical
environments, and the proximity effects of surfaces and interfaces with
an emphasis on the relationships between physical behavior and the
microstructure and defects in the material. Included within the activity
are research in aqueous, galvanic, and high-temperature gaseous
corrosion and their prevention; photovoltaics and photovoltaic junctions
and interfaces for solar energy conversion; the relationship of crystal
defects to the semiconducting, superconducting and magnetic properties;
phase equilibria and kinetics of reactions in materials in hostile
environments, such as in the very high temperatures in energy conversion
processes; and diffusion and transport phenomena in ceramic electrolytes
for improved performance in batteries and fuel cells. Basic research is
also supported to develop new instrumentation, including in-situ
experimental tools, to probe the physical behavior in real environments
encountered in energy applications.

**Unique Aspects:**

Research in this activity provides the primary support of the
fundamental understanding and identification of detailed mechanisms
responsible for the physical behavior of materials, and the
incorporation of this knowledge into reliable detailed predictive
models. The understanding that has resulted from such modeling work has
already led to the design of unique new classes of materials including
compound semiconductors, tough structural ceramics, ferroelectrics, and
magnetocaloric materials. Some specific examples include: new levels of
magnetic properties from nanoscale clusters, compound semiconductors
that can remove excess CO~2~ from the atmosphere, highly desirable
phases of ferroelectric materials that can be formed through novel
processing techniques, and a breakthrough in understanding of the
chemistry of friction enabling the tuning of lubrication layers.

**Relationship to Other Programs:**

BES:

-   Closely linked with activities under Engineering Physics, Structure
    and Composition, Mechanical Behavior and Radiation Effects,
    Synthesis and Processing Sciences, X-ray and Neutron Scattering, and
    Condensed Matter Physics

-   Linked with Center of Excellence for Synthesis and Processing of
    Advanced Materials

-   Linked with Computational Materials Sciences Network

Other Parts of DOE:

-   Solid State Lighting/Building Technologies Program, Office of Energy
    Efficiency and Renewable Energy

-   Nuclear Energy Research Initiative

-   Energy Materials Coordinating Committee

-   Hydrogen Coordinating Committee

Interagency:

-   Interagency Coordination Group on Metals (NSTC/CT/MatTec)

-   Interagency Coordination Group on Structural Ceramics
    (NSTC/CT/MatTec)

-   Interagency Coordination Group on Nondestructive Evaluation
    (NSTC/CT/MatTec)

-   Interagency Working Group on Nanotechnology (NSTC/CT/MatTec)

-   OSTP Interagency Coordination Group on Hydrogen

**Significant Accomplishments:**

This activity has had broad and significant impact in many classes of
materials and phenomena. In magnetic materials, continuous fundamental
studies of bulk alloys and nanoclusters have led to the following
breakthroughs:

-   Discovery of the extraordinary giant magnetocaloric phenomena, which
    has led to the demonstration of high-efficiency refrigeration that
    does not require the use of any refrigerant. This technology
    completely eliminates ozone depleting chemicals (e.g., Freon) used
    by conventional refrigeration and has the potential to develop into
    a global market.

-   Development of ferromagnetic bulk metallic glasses with dramatic
    reductions in hysteretic energy loss, which has the potential of
    leading to \$30 billion dollars per year in savings in improved
    energy efficient motors and transformers.

-   The prediction and validation of extremely large magnetic moments in
    nanoclusters, which has the potential of leading to higher density
    nanomagnetic storage devices.

In semiconductors, major research accomplishments in silicon-based and
other compound semiconductors are:

-   Developed a biocompatible semiconductor laser for the rapid
    detection and analysis of chemical agents, such as anthrax spores.
    The device was based on recent advances in the surface chemistry of
    semiconductors and the concept of quantum squeezing of light emitted
    through a spore flowing at high speed in the laser's microcavity.
    This field-deployable biolaser should be able to identify different
    types of spores (e.g., anthrax) within a large population of
    harmless spores rapidly and effectively.

    -   Through research in wide band-gap semiconductors achieved a
        succession of world records for energy conversion efficiency in
        solar photovoltaics and been recognized by the 2001 John Bardeen
        Award from the American Physical Society.

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-   Developed a new dielectric technology for capacitors, based on high
    dielectric constant ceramic perovskites oxides. The new technology
    overcomes the conventional silicon dioxides thickness limitation of
    two to three nanometers (three to five atomic layers), and thus
    offers promise of further extending Moore\'s Law which predicts the
    doubling of the performance/cost ratio for silicon-based devices
    every eighteen months. This breakthrough promises smaller, faster
    field effect transistors leading to faster and more versatile
    computers.

-   Achieved a tenfold increase in the electrical conductivity of the
    semiconductor gallium arsenide which is now attracting market
    interest for application in electronic devices, diode lasers,
    reading compact discs, and ultra-high speed transistors.

-   Achieved a new milestone towards light-emitting silicon through the
    identification of oxygen atoms as the mediator of silicon energy
    states. The result suggests possible ways to enhance light emitting
    efficiency of silicon, and hence easier and cheaper ways to
    integrate optoelectronic components with silicon-based technology.

Other major accomplishments supported by this activity are:

-   A "direct" visualization of the three-dimensional rearrangements of
    atoms in a crystal lattice triggered by a magnetic field was
    realized by an *in-situ* x-ray diffraction technique. The
    observation sheds light on the mechanism governing the
    magnetocaloric effect and paves the way to designing advanced
    materials for improved environmentally-friendly cooling
    technologies.

-   Two-dimensional (2D) photonic band gap crystals in the visible
    wavelength have been fabricated based on the self-assembled periodic
    arrays of aligned carbon nanotubes. These aligned periodic carbon
    nanotubes are unique as they exhibit a "tunable" photonic bandgap
    not previously observed in the visible region and demonstrate the
    feasibility of fabricating large areas of 2D photonic crystals
    without sophisticated electron lithography procedures. These
    photonic crystals may find wide applications in optical signal
    processing and switching.

-   A synergistic approach of combined photoelectron spectroscopy and
    quantum chemical calculations has provided crucial insights on the
    origin of the loss of nobility and the catalytic properties of
    nanoscale gold particles.

-   An innovative visualization tool has provided new insights in the
    corrosion behavior of aluminum and its alloys. The results show that
    the "noise" from electrical signals is dominated by the pit growth
    processes as opposed to the initiation and re-passivation of
    protective oxides speculated previously and observed in stainless
    steels.

-   Strong coupling and giant magnetic moments were predicted in
    manganese atom clusters in the presence of nitrogen. The predictions
    are consistent with recent experimental results and the finding will
    aid the design of new magnetic materials and novel spintronic
    devices.

-   Novel zinc oxide nanostructures, including hierarchical structures
    with different symmetries, nanobridges, and nanowalls have been
    synthesized by an innovative vapor transport and condensation
    technique. The results demonstrate the feasibility of joining two
    different nano-components into a hierarchical structure. The
    nano-composites exhibited superior electrical and thermal
    conductivities.

-   Russian doll models for the stabilization of silicon cage structures
    found that unfavorable energetics in the stretching of silicon to
    silicon bonds were responsible for previous failed attempts to
    synthesize the 60-atom silicon structure.

-   A new epitaxial liquid-assisted growth method, which involves a
    fluoride compound in precursor films, has been developed to grow
    thick films of superconducting YBCO. The study yielded an
    understanding of the complex and unconventional growth process,
    which involves reactions of precursor films to form the desired
    compounds in several sequential steps. The understanding can be
    extended to other technologically important oxides that are of
    critical importance in solid-state electronic devices.

-   Nanocrystals of semiconductor cadmium selenide were demonstrated to
    successfully remove excess carbon dioxide from the atmosphere. The
    technology could potentially convert unwanted carbon dioxide into
    useful organic molecules with major environmental benefits.

-   Experimental studies of interfacial forces have resulted in an
    atomic understanding of interfacial adhesion and the ability to tune
    frictional forces at the atomic level. The development of
    instrumentation that enabled this work was recognized by an R&D 100
    award.

-   Pioneering work in rare earth alloys, recognized by another R&D 100
    Award, has led to high performance phosphors that are now marketed
    in television tubes, and cheaper and more powerful permanent
    magnets, including the development of a new market and the spawning
    of a private sector company that markets it.

-   A new wetting model was constructed and validated by recent AFM
    observations of the interfacial structures between molten metals and
    ceramic surfaces. The model takes into account diffusion of the
    solid substrate under the molten metal and successfully explains why
    the contact angle differs for droplets that are growing versus those
    that are evaporating. Understanding the behavior at these
    metal-ceramic interfaces is critical to improving various industrial
    processes including soldering, brazing, coating, and composite
    processing.

-   An innovative approach enabled the first direct observation on how
    water behaves near a hydrophobic surface. Measurements made by the
    surface force apparatus revealed the thrashing and rippling behavior
    of water near hydrophobic surfaces. These insights open doors to
    understanding a wide range of biological dynamic processes from
    protein folding and enzyme reactivity.

-   A new study confirms the theoretical analysis that molecules of
    hydrogen, oxygen, and even water can travel across conducting
    membranes in opposite directions from what would normally be
    expected from chemical potential gradients. The new analysis shows
    that the behavior is a result of the simultaneous, coupled transport
    of multiple conducting species. The understanding of membrane
    transport is important in the development of advanced materials for
    energy storage such as fuel cells.

    **Mission Relevance:**

Research underpins the DOE missions by developing the basic science
necessary for improving the reliability of materials in chemical,
electrical, and electrochemical applications and for improving the
generation and storage of energy. With increased demands being placed on
materials in real-world environments (extreme temperatures, strong
magnetic fields, and hostile chemical conditions), understanding how
their behavior is linked to their surroundings and treatment history is
critical. Research in mission-relevant topics in this activity include
corrosion, which annually consumes 4.2 percent of the Gross National
Product; photovoltaics; fast-ion conducting electrolytes for batteries
and fuel cells; novel magnetic materials for low magnetic loss and
high-density storage; and magnetocaloric materials for high-efficiency
refrigeration. The photovoltaic research supported is complementary to
Experimental and Theoretical Condensed Matter Physics, whose emphasis is
on the electronic structure of solar conversion processes and systems.
Significant interactions and collaborations exist between this activity
and Materials Chemistry and Biomolecular Materials program in surface
chemistry and electrochemistry as related to oxidation and corrosion
research.

**Scientific Challenges:**

The challenge in this area is to develop the scientific understanding of
the mechanisms that control the behavior of materials and to use that
understanding to design new materials with desired behaviors. The
program encompasses efforts aimed at understanding the behavior of
organic and inorganic electronic materials, magnetism and advanced
magnetic materials, manipulation of light/photonic lattices,
corrosion/electrochemical reactions, and high-temperature materials
behavior through intimately connected experimental, theory, and modeling
efforts leading to a-priori design of new materials.

**Funding Summary:**

Dollars in Thousands

[FY 2005]{.underline} [FY 2006]{.underline} [FY 2007
Request]{.underline}

25,551 24,677 29,756

> [Performer]{.underline} [Funding Percentage]{.underline}
>
> DOE Laboratories 77%
>
> Universities 23%

These are percentages of the operating research expenditures in this
area; they do not contain laboratory capital equipment, infrastructure,
or other non-operating components.

**Projected Evolution:**

In the near term, four central topics define the current program:
electronic and magnetic behavior of materials; corrosion and
electrochemistry science; nano-scale phenomena; and multiscale modeling
of materials behaviors. Major efforts in these areas will continue.
Increased investment in organic electronic materials will be considered.
In addition, focus in theory and modeling at universities and national
laboratories, taking advantage of the vast advances in computing speed
and power, will be emphasized.

In the mid- to long-term, in order to understand the macroscopic
behavior of materials it is important to understand the relationship
between the material's structure and its response to external stimuli.
One needs to first study the structure over all length scales, with
emphasis at the atomic level, and to understand the response of the
nanometer and larger features of the material to those external stimuli.
Studies of the physical response of a single nanometer-scale feature
needs to be related to the macroscopic behavior of the material. This
can often be done with modeling but further advances are necessary to
fully couple the length scales from atomic to macroscopic. Currently,
atomistic simulation methods can be used to study systems containing
hundreds of thousands of atoms, but these systems are still orders of
magnitude too small to describe macroscopic behavior. Continuum methods,
typically using finite element methods, fail to adequately describe many
important properties because they use phenomenology that has little
connection to the real processes that govern physical interactions.
Modeling at an intermediate length scale, the mesoscale, where many
defects can be included and from which predictive models at the
continuum scale can be developed is required for advances in materials
science. At this intermediate length-scale it is necessary to model the
collective phenomena that include well over a billions atoms. Developing
and applying novel techniques to these problems will be emphasized in
coordination with the investment in theory and modeling. In addition,
tremendous advances in organic-based electronic materials applications
have been reported recently. This program seeks to foster theory,
modeling and simulation activities that address the following key topics
in organic electronic materials: charge and energy transfer; electronic
structure calculation; exciton dynamics and transport; and spin
dynamics.

Finally, in order to understand the complex phenomena that are linked to
both a material and its local environment, a long-term investment is
needed. During this funding period, we anticipate supporting programs
that apply advances in both experimental techniques and computational
methodologies to understand the macroscopic behavior of materials by
studying materials at all length scales and multiple time scales. In
particular, bridging models covering the mesoscale (covering phenomena
in the range of 0.1 to 10 microns) will be developed. This is vital to
linking disparate length scales and creating a scientifically rigorous
understanding of materials performance and behavior. It is also vital to
link the time scales that correspond to fast reactions and relaxation
processes in materials.