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Preparation of Hexaboride Nanocubes by Solution Combustion Synthesis
We have worked on a combustion synthesis methodology for the synthesis of non-oxide ceramics. Combustion synthesis is a technique that has been extremely successful for the preparation of oxides, but until now had never been shown to be effective for borides. Work in our laboratory focuses on the preparation of nanocubes of rare-earth hexaborides, including LaB6, SmB6, EuB6, and YbB6. The figure below shows the hexaborides that can be produced by this technique, as well as those that cannot be prepared by this technique. The resulting powders are well-defined nanocubes.
Particle Size Effects in the Thermal Conductivity of Copper Nanofluids
We have pursued efforts to understand the effects of powder agglomeration and thermal conductivity in copper-based nanofluids. We have proposed a definite correlation between an experimentally determined particle size distribution from dynamic light scattering and the thermal conductivity enhancement of the nanofluid with respect to nanopowder loading. |
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Solvothermal Synthesis of Ultra-high Temperature Ceramics
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We have explored the use of a solvothermal process for the synthesis of tantalum carbide and other non-oxide ceramics. The particle size distributions (on the left) from dynamic light scattering show particles that are ~100 nm on average. For a material such as TaC, these particle sizes are some of the smallest that can be found. The crystallite size of the powders is 25 nm, showing that the powders are agglomerated to some extent, but the level of agglomeration is very minor. The technique used for the preparation of the TaC can also be applied for HfC, BN, TiN, among others.
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Stability Analysis of Reverse Micelle Systems using Dynamic Light Scattering and Molecular Dynamics
We have used molecular dynamics simulations and dynamic light scattering measurements to analyze the size of reverse micellar structures in the AOT-water-isooctane system at different water-to-surfactant ratios at ambient temperature and pressure. The combination of molecular dynamics and dynamic light scattering allows a better interpretation of the experimental results, in particular for conditions where the structures are nonspherical, commonly observed at lower water-to-surfactant ratios. We have also analyzed the effect of zirconyl chloride on the micellar size distributions in this system. |
Reverse micellar systems have a wide range of applications, from protein extraction to synthesis of nanoparticles. They also have an important role during transport processes in biological systems.
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Luminescence Behavior of Europium-doped Hydroxyapatite
We have completed a detailed analysis of the luminescence behavior of europium-doped hydroxyapatites. For the case of calcium-deficient hydroxyapatite we found the typical emission from Eu3+, but also a broad emission with two peaks at 420 and 445 nm, corresponding to the 8S7/2 transition of Eu2+.
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