Chemistry Department Seminar: Dr. Efrain Rodiguez
Abstract:
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 such as (AOH)-CoCh. 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.
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