The innovation engine for new materials

New Layered Transition Metal Chalcogenides as Functional Materials

Seminar Group: 


Prof. Efrain E. Rodriguez


Department of Chemistry and Biochemistry
University of Maryland, College Park


Monday, March 20, 2017 - 4:00pm


MRL Room 2053


Prof. Ram Seshadri

We present a new set of layered materials that, unlike transition metal dichalcogenides, are built of square metal lattices leading to new functional properties such as unconventional superconductivity and ferromagnetism. Due to the weak van der Waals interactions that hold the chalcogenide layers together, intercalation chemistry in aqueous solutions can be utilized to prepare new phases with interesting magnetic and electronic properties. We will present our work on the synthesis, characterization, and structural studies via neutron and X-ray scattering of these layered materials. Our group’s strategy has been to incorporate layers such as metal hydroxides to understand superconductivity in the iron chalcogenides such as (AOH)-FeCh materials where A is an alkali metal and Ch = S2– and Se2–. We will also present our studies of the cobalt analogues of these layered materials including synthesis of a metastable form of CoCh and its intercalated derivatives. Unlike the case of iron, the cobalt-based materials express weak ferromagnetism instead of superconductivity. We attempt to explain the stark changes in the properties from their electronic structures calculated utilizing density functional theory.