This Materials World Network (MWN) research project will investigate charge transport in trivalent-ion tungstates. Most solid electrolytes conduct electrical charge via monovalent (1) or divalent (2) ionic species. Reports of trivalent-ion conduction in tungstates with the scandium-tungstate-structure type have led to some debate regarding the nature of the charge carrier. Some reports suggest that trivalent cations are primarily responsible, while others suggest that the polyatomic tungstate anion, WO42-, is more mobile. A better understanding of how charge is transported in these materials may lead to the development of new solid-state electrolytes and devices, like fuel cells, batteries, and ion separators. To elucidate the transport mechanisms in these materials, a combination of experimental and computer modeling techniques will be used. Electrochemical studies will be performed on specimens with well-characterized structures under conditions compatible with the assumptions of the theoretical models. Modeling activities will build upon the experimental knowledge and provide predictions that can, in turn, be tested by specially designed experiments. The project will be conducted as an international collaboration among researchers at Alfred University (AU) in the United States, Ural State University (USU) in Russia, and National University of Singapore (NUS). At AU and USU, materials will be synthesized and characterized using electrical methods to probe ion transport and reactivity. At both AU and NUS, diffraction and computer modeling will be conducted to determine crystal structures and ion transport mechanisms, respectively. This collaborative project provides both scientific and educational benefits. Mutual exchanges among research groups will bring together complimentary expertise in solving this challenging problem. Graduate students will visit and work with researchers at partner institutions to gain a more global perspective, both in terms of scientific and cultural awareness. The US portion of this project is co-funded by the East Asia and Pacific Program (EAP) of the NSF Office of International Science and Engineering and by the Ceramics (CER) program of the Division of Materials Research (DMR).
