Title: "Hidden Complexity in Inorganic Solids: Structural Disorder, Unusual Bonding, and Structure-Property Relationships"

Sviatoslav Baranets, Assistant Professor

Louisiana State University

Host: Kirill Kovnir

Abstract: Zintl phases are polar intermetallic compounds characterized by the coexistence of covalent and ionic bonding interactions. Their crystal structures frequently feature complex (poly)anionic frameworks, with structural complexity and disorder representing important elements in the discovery of materials with unusual physical properties. Eu-bearing Zintl pnictides are particularly interesting in this context because of their diverse structural chemistry, complex magnetic behavior, and pronounced response of charge transport to applied magnetic fields. Here, we present the discovery, synthetic challenges, comprehensive structural characterization, electronic structures, and magnetic and transport properties of multinary arsenides in the complex Eu–M–As (M = Zn, Ga/Zn, Ga/Sn, In/Sn) systems. A specific focus will be placed on the chemical origins of pronounced structural disorder, including mixed-metal occupancies and competition between alternative structural building blocks. These materials exhibit diverse physical properties, including colossal magnetoresistance, magnetic anisotropy, and thermoelectric response. We discuss relationships between their structural arrangements, bonding, and physical properties, and their potential as platforms for studying the interplay between magnetism and charge transport. We also present a reassessment of the seemingly simple textbook binary Se–Br system, in which detailed structural analysis reveals unexpected compositional and bonding complexity.

Bio: Sviatoslav Baranets is an Assistant Professor of Chemistry at Louisiana State University. His research focuses on the discovery and development of new inorganic functional materials, particularly heteroanionic semiconductors and Zintl cluster compounds for energy applications. His group combines solid-state and wet-chemistry synthesis with X-ray and neutron crystallography, electronic structure calculations, spectroscopy, and transport-property measurements to understand relationships between the structures and properties of emerging materials. [lsu.edu], [faculty.lsu.edu]

Baranets earned his Ph.D. in inorganic chemistry from the Institute of General and Inorganic Chemistry of the National Academy of Sciences of Ukraine in 2015, working with Sergiy Volkov. He later conducted postdoctoral research with Svilen Bobev at the University of Delaware before joining the Louisiana State University faculty in 2022. He is a recipient of an NSF CAREER Award and the Ralph E. Powe Junior Faculty Enhancement Award supporting his research on new semiconducting materials for thermoelectric applications and the conversion of waste heat into electricity.