Report on the U.S.-Japan joint seminar on Transport in Non-Stoichiometric Compounds

Abstract

From October 10-12, 1979, a U.S.-Japan joint seminar, "Transport in Non-Stoichiometric Compounds" was held at the East-West Center in Honolulu, Hawaii under the sponsorship of the Japan Society for Promotion of Science and the U.S. National Science Foundation. This was a follow-up seminar to the earlier "Defects and Diffusion in Solids" seminar held in Tokyo, October 4-6, 1976. The purpose of this seminar, at which there were eight Japanese participants, eight U.S. participants, and one U.S. observer, was to bring together scientists from the two countries for discussions of transport in nonmetallic solids including oxidation and sulfidation reactions of metals, the role of defects in nonmetallic solids and transport in solid electrolytes. The research papers were not published as a symposium proceedings but each author was free to submit his paper to the journal of his choice. A brief summary of the highlights of the program is presented here to acquaint readers with recent developments and the discussions of papers. The sessions were divided into three areas. These were (1) Synthesis, Properties, and Application of Solid Electrolytes; (2) High-Temperature Corrosion; and (3) Defects and Transport Properties of High Temperature Materials. T. Takahashi reported on his extensive research on high oxide ion conduction in sintered oxides. Some perovskite-type oxides of general formula, ABO3 were found to be oxygen ion conductors when A or B was substituted with a cation of lower valency. Such materials were accompanied by p-type electronic conductivity under high partial pressure of oxygen and a small n-type electronic conduction under low oxygen partial pressures. The oxygen ion conduction is via anion vacancies. Examples of such oxides were CaTio.7Alo.303_~, CaTio.sAlo.503_~, CaTio.95Mgo.0503_~. These *Center for Solid State Science, and Department of Physics, Arizona State University, Tempe, Arizona 85281. 501