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Research Interests
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brian woodfield research interests
Research Interests by Brian F. Woodfield.
| Specific Heat Measurements In my laboratory we use specific-heat measurements from 0.5 K to as high as 400 K to study the properties of superconducting, magnetic, and other technologically important materials. Specific heat has been an important tool in the study and understanding of solids for more than seventy years where it has been used to investigate and understand lattice vibrations, metals, superconductivity, electronic and nuclear magnetism, dilute magnetic systems, structural transitions, heavy fermions, and more. The specific heat has been useful because it is a bulk property; that is, the specific heat is an average measure of the thermal properties of a sample which, in turn, has provided unique and significant insights of the intrinsic properties of a material. While commercial specific heat apparatuses using relaxation methods exist, our custom designed and built instruments are capable of accuracies and precisions approaching, and even exceeding, 0.1%. This type of accuracy and precision allows us to study a wide range of interesting and relevant topics in solid-state physics and chemical thermodynamics. Some of the topics we have studied in the past include (1) the thermodynamic stability of nuclear waste materials, (2) zeolites, (3) negative thermal expansion materials and low energy vibrational modes, (4) frustrated magnets, (5) iron oxides and oxyhydroxides, (6) uranium metal, and (7) neutron detector materials. Shown below is an example of our measurements on a bulk sample of MnO and a sample of the collosal magnetoresister La1-xSrxMnO3.  Currently, our primary research interest is in the Energetics of Nanomaterials, which is funded by the Department of Energy. Our focus in this research project is to understand the fundamental driving forces governing the stability of materials as their particle sizes reach the nanoscale. We have done extensive work on high quality samples of the TiO2 polymorphs of anatase and rutile with sizes of 7 nm and on the magnetic material CoO. More information can be found in our papers given in the publication list. Synthesis of Nanoparticles  As
part of our nanoscale project, we have recently developed an elegantly
simple process that allows us to make a nearly unlimited array of
well-defined inorganic nanoparticles that have controlled sizes from 1
nm to bulk. The particles are highly crystalline with well defined
shapes (usually spherical but also rods), we can synthesize them with
chemical and phase purities as high as 99.9999%, we can control the
particle size distribution to approximately ±10%, we project
with confidence that we can make industrial size quantities with
manufacturing costs significantly less than any other current
technique. The types of particles we can make are, in general, metal
oxides, but the process allows us to control the oxidation state so we
can make high, medium, and low oxidation state oxides and metals. We
can make oxides of all of the transition metals, lanthanides, and
actinides, AND any stoichiometric combination of any number of these
metals. We can include group I and group II metals in combination
with the transition metals. Consequently, we have the ability to make
an almost innumerable array of nanomaterials (single metal and
multi-metal) with well-controlled physical properties, purity,
oxidation state, size and size distribution using a process that is
fast, reliable, and inexpensive. Table 1 gives examples of some of the
materials we have synthesized, and below are some representative TEM
images for NiO, Y2O3, and CoO powders. |
