This research seeks to understand the role of catalysts in hydride structures. X-ray absorption spectroscopy is used to examine the chemical interaction of catalysts (TiCl3) with the host hydride powder (NaAIH4). Results show that TiCl3 transforms first to metallic Ti-then reacts with Al3+ in NaAIH4 to form TiAlx complexes. It remains unclear, however, whether the formation ofthose TiAlx complexes is directly related to catalysis ofthe H2 desorption reaction in the hydride. Ultrasmall angle x-ray scattering (USAXS) is used to study trends in powder surface area with various treatments. Powder surface area is an indicator of, hydride particle damage accumulation (i.e. crack formation in and fracture of the particle) during high energy ball milling to add catalysts and during hydrogen desorption. Sodium alanate (NaAIH4) powders are routinely high energy milled with the transition metal salt catalysts, TiCl2, TiCl3, ZrCl4, and VCl3. Our research studies the variation in powder surface area with milling time and with desorption treatment. Results show that NaAIH4 has an inherently high surface area (characterized by the surface fractal morphology) and that after catalyst introduction by high energy ball milling, higher surface areas are retained for catalysts which show the best desorption kinetics and lowest surface areas are yielded for poorly performing catalysts. After desorption, the surface area was lower, relative to the undesorbed powders, in all cases. Variation in powder surface area is attributed to long-range diffusion in the hydride powders. Transition metal salts may playa role in enhancing or inhibiting diffusion in the host material. Combined, these synchrotron X-ray studies (i.e. absorption spectroscopy and scattering) attempt to differentiate between chemical contributions of the transition metal salt (i.e. acting as catalyst for chemical reactions) and transport kinetic contributions (i.e. acting to promote higher diffusivity).
Tabbetha A. Dobbins is an assistant professor with a joint appointment in physics at Grambling State University and Louisiana Tech University. During her tenure in this position, she has mentored students in both graduate and undergraduate research projects and promoted the student's scientific research. She has also held visiting appointments at the Louisiana State University (Dept. of Physics & ~ Astronomy) during Spring 2009 and at Rowan University (Dept. of Physics & Astronomy) during the AY 2010-11- and has thus engaged in broadening participation of students in synchrotron studies. After receiving her doctorate from Penn State University, she was awarded the prestigious National Research Council Post-Doctoral Fellowship to do research at the National Institute of Standards and Technology.
Her dissertation focused on how high-temperature thermal spray conditions affected the quality of thermal barrier coatings; a critical component to the performance of gas turbines for power generation and of commercial jet engines. She continues to do cutting edge research in applying synchrotron x-ray analysis to modem engineering problems in carbon nanotubes, gold nanoparticles, the hydrogen fuel economy, and polymer self-assembly. She has already garnered an excellent record of publication in the top journals for materials-which includes 21 scholarly publications.
Tabbetha also excels in public outreach in the sciences. She works diligently to engage Grambling State and Louisiana Tech Universities in high school outreach programs. One focus of this effort is on introducing students to - instrumentation and to the excitement of materials research in a prior funded (NSF) project titled 'Nanoscale Measurement and Analysis' Workshop. Her research programs are aimed at attracting and recruiting students to the sciences using societally relevant energy-related and biomedical-related topics. She is a 2009 recipient of the National Science Foundation CAREER Award for a project titled: "Enhancing Atomic Mobility and Desorption Kinetics in Metal Hydrides".
Dobbins' demonstrated commitment to both science and society is highly unique. Her innovative programs and expanding reputation in materials research prove that she is a model young faculty member poised to make significant, long-term impacts on materials research and education. She "currently lives in Ruston, LA, where she is a member of the Louisiana Science Teacher's Association and served on the Louisiana State University Center for Advanced Microstructures and Devices x-ray user participation committee from 2004-2007.
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