CAREER: Control of Functionality in Transition Metal Oxides with Metal-Metal Bonding

Suny At Stony Brook, Stony Brook NY

Investigators

Abstract

TECHNICAL SUMMARY: This research supported by the Solid State and Materials Chemistry program aims to control the functionality of materials by targeting specific electronic structures through "internal design" principles rather than through less direct structure-property relationships. This approach will be used to find new thermoelectric materials within the class of transition metal oxides with direct metal-metal bonding, which lifts the typical degeneracy of the d-electron states giving rise to both small band gap semiconductors and high density-of-states metals. A thorough investigation of physical properties (such as resistivity, magnetism, thermopower, and thermal conductivity) will be undertaken to explore whether the f¬-electron-like states of these compounds can be tuned to produce improved materials performance, and whether these unusual electronic states give rise to any unexpected phenomena. In addition, spectroscopic studies of these materials will be carried out to test the potential of these materials as stable small band gap semiconductors for optical applications. Through these investigations, it should be possible to develop a framework for better understanding this intriguing class of compounds. This work will be supported by efforts to develop synchrotron microcrystallography techniques with the long term goal of obtaining single crystal diffraction data from the crystallites in typical powder samples. NON-TECHNICAL SUMMARY: The performance of many high-tech devices is limited by the properties of the solid state materials from which they are built. This project will test new strategies for designing solid state materials for energy applications, directly incorporating theoretical calculations into the design process to efficiently discover improved materials. The primary target of this project is better thermoelectric materials, which have applications for electricity production through waste heat recovery, satellite power generation, and efficient solid state refrigeration. The metal oxide systems being studied may also provide new superconducting compounds and new small band gap semiconductors for infrared (IR) detection applications that can serve as air stable and non-toxic alternatives to current systems based on cadmium mercury telluride compounds. The fundamental synthesis, characterization, and theoretical skills necessary to understand and carry out the "internal design" of materials will be integrated into teaching and outreach efforts, as they provide the key insights needed to generate materials solutions for energy and other societal challenges. Particular emphasis is placed on crystallography, including national educational efforts aimed at addressing deficiencies in typical academic curricula and at broadening participation in experiments at x-ray and neutron national laboratory facilities. Active research mentoring of students interested in energy research at all levels will be a key component of this effort, including the diverse undergraduate and high school students in the New York City Metropolitan area.