POWRE: In Situ Study of Stabilization of Zirconia by Anion Exchange (N for O) Using High Temperature, Controlled Atmosphere X-ray Diffraction at University of Tubingen (Ger)

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9806000 Sharma This research addresses the thermodynamics, kinetics, reaction path, structure and composition of intermediate phases, atomic level structural mechanism of the reaction of Zr containing compounds with N2 and NH3. In situ x-ray diffraction studies will be conducted at the University of Tubingen, and transmission electron microscopy at Arizona State University. The approach is to synthesize zirconia phase(s) with randomly ordered oxygen vacancies by anion (N for O) substitution. Most of the studies of zirconia stabilization are concentrated on cation substitution, preferably by a lower valent ion such Y or Ca, to create randomly ordered oxygen vacancies. Some zirconium oxynitride with ordered oxygen vacancies in the lattice have been synthesized, but randomly ordered vacancies are required for a material to be used in solid oxide fuel cells. The present project is directed towards a preliminary study that will lead to a detailed systematic investigation of the Zr-O-N system. Various Zr containing compounds such as ZrO2, Zr(SO4)2, Zr(OH)4, Zr(NO3)4.6H20, ZrOCl2 and (NH4)3ZrF7 will be heated in a N2 or NH3 atmosphere, and time, temperature resolved x-ray diffraction, electron diffraction, high resolution electron microscopy and electron energy loss spectroscopy will be used to elucidate the reaction path and identify all phases. %%% This is a research enhancement grant made under the Professional Opportunities for Women in Research and Education (POWRE) program. The research will contribute new materials science knowledge at a fundamental level. Progress in understanding the reaction path is expected to advance the potential to synthesize technological important materials by design.