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Crystalline Materials
SNS will provide insight into
ways to tailor the structures and properties of
new materials, enabling us to do more with less. |
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| Thin films that
can be probed by SNS will be used for nonvolatile
memory, extending the life of laptop computer batteries. |
From cookware to computer
chips to prescription drugs, many materials used every day are made of crystals
that possess special properties. The properties of any material are largely determined
by how its atoms are arranged. For crystalline materials, how the atoms are arranged
in individual crystals and how the crystals themselves are arranged are both important.
Many modern synthetic materials have intentionally tailored atomic or crystal
arrangements.
Knowing how atoms are arranged
in new compounds is a key to understanding how to chemically
and physically tailor materials to get the desired
properties (e.g., for use in a new electronic device).
Neutron scattering is a powerful tool for determining
how atoms are arranged in individual crystals and
how crystals are arranged in polycrystalline materials.
Moreover, neutron scattering can reveal the changes
that occur in crystal structure as the material is
exposed to changing pressures, temperatures, or other
environmental variables. Understanding how a process
alters a material's structure provides important
clues on how to improve a material's properties (e.g.,
to produce a new material that won't break when heated)
or determine how a material will behave under extreme
conditions.
Our understanding of the
fundamental behavior of technologically important materials,
such as catalysts, ionic conductors, superconductors,
alloys, ceramics, cements, magnets, and radioactive
waste forms, will continue to be improved by neutron-scattering
measurements. In addition, the higher neutron flux
of SNS will greatly expand the range of feasible
study in material science. It will be possible to
study much smaller samples, such as multilayer thin-film
structures typical of today's electronic devices
(e.g., compact-disc players) that will be used in
future devices for improving laptop computers, inkjet
printers, video recorders, and cellular phone networks.
How physical properties of materials are influenced
by the reduced size in various dimensions of new
materials' building blocks (e.g., nanoparticles,
nanofibers, multilayer thin films) is a growing
area of interest because such understanding offers
a new avenue for tailoring material properties. Neutron
scattering will impact this area, as well as the
related and newly developing areas of self-assembly
of complex crystals and processing of biomimetic
structures.
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"Seeing" the
atomic arrangement of carbonate apatite, a major
component of teeth and bones, could lead to similar
synthetic materials. |
The ability of SNS
to provide a full neutron diffraction pattern every
few minutes (or even seconds) will allow "time-resolved" studies
of many processes in operating chemical cells. Scientists
can follow at the molecular level actions of the
following"
- A fast ionic conductor
in an operating battery or fuel cell
- The effects of changing
temperature (or other variables) on the action
of a catalyst such as zeolite, used in the petroleum
and chemical industry, or of a metal-supported
catalyst used to clean automobile exhaust
- Changes in crystal structure
of a spinning turbine blade as it heats up and
deforms
- Change in particle size
of Portland cements as they take up water
- Changes that occur in
earth materials placed under increasing pressure
in multianvil presses for geological studies
SNS will
enable scientists to probe small samples such
as thin films for use in superconductor microwave
devices for cell phone networks. |
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Study of these changes
will create data that will be useful for modeling the internal structure of the
earth and other planets to understand large-scale dynamic processes such as crustal
plate motion, mantle convection, volcanism, earthquakes, and planetary magnetic
fields.
The high-performance materials
for future technologies will be chemically and structurally more complex, but
they will give us the ability to do more with less, provide greater environmental
friendliness, and make more science fiction come true. Material science and structural
chemistry are frontiers for exploration that require an increasing role for neutron
scattering.
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