With support from the Solid-State and Materials Chemistry Program in the NSF Division of Materials Research, the proposed research focuses on transition metal oxides AMO2 (A = alkali metal, M = 3d metal) with CdI2-type layers. AMO2 phases demonstrate a large variety of physical properties, including geometrically frustrated magnetism, spin, charge and orbital ordering, thermoelectricity, and nonconventional superconductivity. In all known AMO2 phases, transition metals are only in the 3+ or 3+/4+ oxidation states. Beta-NaFe2O3 is the only known compound with a layered rock-salt related structure and double layer transition metal-oxygen block. The main components of this proposal are synthesis, crystal structure and physical properties investigation: (1) of novel layered phases with CdI2-type layers and M in uniquely low (for such phases) 2+/3+ mixed valent oxidation states and (2) of new n = 2 and n = 3 members of the layered rock-salt related homologue. It is envisioned that implementation of the stated proposal objectives will not only result in novel strongly correlated-electron oxides, but also provide new synthetic methodologies for the preparation of highly unusual phases as well as result in new fundamental insights into correlated-electron behavior, leading to the discovery of compounds with potentially useful thermoelectric and/or magnetic properties.
NON-TECHNICAL SUMMARY
In a special class of metal compounds electron - electron interaction results in a variety of physical properties important from fundamental and technological points of view. Properties of these so called strongly correlated-electronic materials depend on details of crystal structure, as well as on transition metal oxidation and spin states. New synthetic methodology developed in this proposal will enable preparation of strongly correlated-electronic materials in a predictable way. Investigation of structure-property relationships will provide deep insights into correlated-electron behavior and enable development of design principles for new materials capable of converting heat via a temperature gradient into electric energy (thermoelectric materials), as well as compounds with interesting magnetic properties. Graduate and undergraduate students will be trained in the areas of inorganic synthesis, electrochemistry, crystallography, magnetism, and various characterization techniques. The PI will lead the organization of the Midwestern Symposium on Undergraduate Research in Chemistry. This symposium, spearheaded by the PI targets the undergraduate to graduate school transition and is designed to increase the number of domestic applicants to graduate programs.
