This project, based on a research collaboration between participants at New Mexico Tech (NMT) and the University of Bayreuth (UBT), Germany, seeks to develop synthesis techniques, electrochemical property measurements and device designs that enable exploitation of a family of ceramics, known as BIMEVOX, with signs of very high oxygen ion conductivity but challenging complex layered structures responsible for two-dimensional transport behavior. A main objective is to build detailed defect chemistry and direction dependent oxygen transport models for the most promising member of this family, Bi4(CuyV1-y)O11-d. Enabled by this fundamental understanding, the successful manipulation of BIMEVOX ceramics could lead to a new class of low-temperature operation (<400 C) electrochemical materials and devices, such as direct ionic thermoelectric O2 sensors, mixed potential gas sensors, de-NOx catalysts, and single chamber fuel cells, all with significant impact on global issues of energy and environment. The project draws upon the respective strengths of the collaborators. Prof. Paul Fuierer at NMT oversees students in the synthesis and structural characterization of textured BIMEVOX ceramics. A unique hot-forging process provides bulk specimens which are idealized with respect to grain orientation and are used to determine the matrices of fundamental second rank tensor properties according to cylindrical symmetry. Hot-forging also provides idealized near theoretical density specimens for electrochemical measurements (pO2-dependent conductivity and thermoelectric power). New powder and thick film techniques can yield larger surface area coatings and membranes with high preferred orientation adaptable to device applications. Prof.-Eng. Ralf Moos, chair of the Functional Materials Dept. at UBT, and supported by the German Science Foundation (Deutsche Forschungsgemeinshaft) provides expertise in the interpretation of thermoelectric and thermo-chemical data, as well as gas-sensor design, construction and testing. His laboratory test benches with precise atmosphere control and conductivity/impedance measurements enable the full range of characterization necessary.
Student appreciation for and mastering of both crystalline structure and defect chemistry in ionic ceramics is an educational goal of the project. Graduate students involved in this project are trained in both fundamental materials characterization and thermo-electro-chemical property measurements using state-of-the-art equipment. The collaboration enhances the scientific and cultural experiences of US students, most notably through semester-long PhD student exchanges and European conferences and workshops. NMT is an EPSCoR participant and has Title III and Title V designation as a Hispanic-serving research institution, so the project contributes to diversity in the science and engineering professions.
