Transmission and Analytical Electron
Microscopy
We have two transmission electron microscopes for materials
research, both maintained under contract with FEI. The
FEI TF30UT is a 300 keV field emission instrument equipped
with an HAADF detector, a CCD camera and an Oxford EDS
detector. This instrument is used for high resolution
imaging and EDX analysis. Our Philips EM 420, a 120 keV
instrument, is equipped with a CCD camera and a Gatan
parallel-detection EELS spectrometer. A Philips heating
holder and a Gatan liquid nitrogen cooling holder are
available. Specimen preparation facilities include
equipment for electrochemical polishing, ion milling,
ultramicrotomy, tripod polishing, plasma cleaning, plus
the standard tools of metallography and optical microscopy.
Scanning Electron Microscopy
We are using an SEM that is maintained by the Geology
and Planetary Sciences Division, and is available at
low cost for analytical
work. We have acquired an ISI SEM, and it has recently
become operational. It is being upgraded for digital data
acquisition. A Hitachi field emission instrument is located
in Applied Physics and
is available for higher spatial resolution SEM work.
X-Ray Diffractometry
Our x-ray diffractometry facilities include a Philips powder
diffractometer, a Siements D-500 powder diffractomter and
an Inel CPS-120 powder diffractometer
system. A liquid nitrogen specimen cryostat has been built
for the Inel system, whereas the Philips diffractometer is
equipped with a high temperature stage. For single crystal
X-ray diffraction, the Haile group maintains a SYNTEX 4-circle
diffractometer. Temperatures accessible with this instrument
also range from 80K to 450K.
Inelastic Neutron Scattering
Professor Fultz is principal investigator on the ARCS spectrometer,
to be built at the Spallation
Neutron Source. ARCS will advance the science of dynamical
processes in materials. Research topics include: (i) studies
of vibrational excitations and their relationship to phase
diagrams and equations of state of materials, including materials
with correlated electrons, and (ii) studies of spin correlations
in magnets, superconductors, and materials close to metal-insulator
transitions.
Mössbauer Spectrometry
The Fultz
group maintains two M�ssbauer spectrometers which can be
equipped with a transmission gamma-ray detector, backscatter
conversion electron detector, or backscatter gamma-ray detector.
A liquid helium cryostat and a furnace allow measurements over
the temperature range 3 - 800 K. One of these units is being
developed for Mössbauer
diffraction experiments.
Calorimetry
We have a Perkin Elmer DSC 7 differential scanning calorimeter,
a Perkin Elmer DTA 7 differential thermal analyzer, Perkin
Elmer DTA 1700 differential thermal analyzer, a Setaram HTC
1800K/DSC 2000K high temperature calorimeter, and a Perkin
Elmer DSC 4 mounted in a liquid helium cryostat. The usable
temperature range for calorimetry spans from 60 - 1800 K.
Thermogravimetric Analysis
For gravimetric analysis we operate a Perkin Elmer TGA 7 with
a temperature capability of up to 1873 K.
Simultaneous Calorimetric and Gravimetric Analysis
For experiments in which sample variability dictates that calorimetric
and gravimentric analyses be performed simultaneously, we
have a Netzsch STA 449. This instrument offers much greater
sensitivity in terms of both thermal events and weight change
than the Perkin Elmer instruments. The temperature range
accessible is 300K to 1873K. An evolved gas analyzer will
soon be installed for elucidating material decomposition
pathways.
Melting and Processing
Ingots can be melted with our Edmund Buehler (Tubingen) D-7400
Arc-Melting Apparatus. Its stainless steel chamber (high-vacuum
capable with O-ring seals) is backfilled with argon gas.
Our second system is an rf induction melting unit that levitation-melts
an ingot on a water-cooled silver-boat under a purified argon
atmosphere. Johnson's group has modified some of the induction
furnaces for work with metallic glasses, such as for injection
molding and for measurements of viscosity with controlled
shear rates. We have an Edmund Buehler ultra-rapid quenching
apparatus for splat-quenching in high vacuum or inert atmospheres.
We also have a thermal evaporator with a cold-trapped diffusion
pump available for making thin films, and a Perkin-Elmer
UHV sputtering system. We have five Spex 8000 shaker ball
mills and a second type of ball mill (Nisshin Corp. NEV-8A)
with two environmentally controlled milling chambers for
milling at temperatures from 100 K to 670 K. A Tetrahedron
hot press is maintained by the Johnson group, and a rolling
mill, swaging machine and many furnaces are also available.
High Temperature Furnaces
For work with ceramics and composites, the Haile group operates
several tube and box furnaces, in many cases with environmental
control. Accessible temperatures are as high as 2073 K.
Transport Measurements
The Haile group maintains three Hewlett-Packard impedance analyzers
for measurements of ion transport characteristics over a
wide range of frequencies (20 Hz to 1 GHz) under controlled
atmospheres and over a wide temperature range. The group
also operates a Solartron impedance analyzer (1 mHz to 1
MHz) interfaced with a PAR potentiostat for electrochemical
measurements, as does the electrochemistry group at JPL.
Facilities for high temperature Hall measurements, Seebeck
coefficient measurements and thermal conductivity measurements
are available through the thermoelectric materials group
at JPL.
Thermal Expansion
The Johnson
group maintains a Perkin Elmer thermomechanical analyzer
model TMA 7, interfaced to a Perkin Elmer thermal analysis
controller TAC 7/DX for measurements of linear thermal expansion.
Fultz's group has constructed a system for differential thermal
expansion measurements at temperatures from 4 - 300 K. The
Haile group maintains a dilatometer for thermal expansion measurements
and studies of sintering and phase transformations at temperatures
up to 1873 K in controlled atmospheres.
Elastic Moduli
Professor G.
Ravichandran in Aeronautics and Solid
Mechanics at Caltech is actively using a 30 MHz ultrasonic
analyzer (Panametrics 5052 UA) for measuring elastic wave speeds
in solid specimens. Transducers for both longitudinal and shear
wave measurements are available, for either transmission or
reflection geometry.
Computers
We maintain several computing resources including a Beowulf
Linux cluster. Graduate students and staff are provided individual
networked personal computers.
Software
The Goddard group has
a broad range of materials simulation software ranging from
the quantum mechanical to the macroscopic levels. A large software
environment has been developed for simulations of phase transformations
and motions of atoms. The COSMOS and ABAQUS finite element
packages are available. We also maintain GSAS and RIETAN packages
for structural analysis with powder diffraction patterns.
Micro
Nano Fabrication Laboratory
This laboratory is a campus–wide resource for thin film processing
for a wide variety of disciplines including:
- Photonics
- Biophysics
- Electronics
- Chemistry
- Materials Science
|
