Solid State Chemistry of Pnictides: Structure and Properties Diversity
Department of Chemistry, Iowa State University
Ames Laboratory, US Department of Energy
Friday, July 23, 2021
Online - For more information, please contact Victoria Van Cappellen (firstname.lastname@example.org).
Pnictides, P, As, and Sb, are capable to form extended polyatomic fragments thus mimicking the chemical diversity of carbon. The structure and properties of metal pnictides are controlled by the electron count and size of metal atoms. When electron count is matching 4 electron per framework atoms, pnictides form tetrahedral framework compounds, inorganic clathrates. We applied a combination of state-of-the-art characterization methods to explore structural chemistry, chemical bonding, and thermoelectric potential of pnictide-based clathrates. Increasing average electron number over four resulted in low-dimensional van-der-Waals layered structures, such as binary tetrel-pnictides, tetrel = Si, Ge, and Sn. We further expanded this topic studying ternary metal tetrel-pnictide which have the tendency to crystallize in non-centrosymmetric structures with promising non-linear optical properties. In many cases the development of the efficient synthetic technique is required to allow properties characterization. Our synthetic efforts are guided by combination of ex-situ annealings, DSC studies, and intensive in-situ studies of synthesis.
Kirill Kovnir is an Associate Professor at Iowa State University Department of Chemistry and Faculty Scientist at US DOE Ames Laboratory. He grew up in Kirovograd, Ukraine. He studied chemistry and received Ph.D. at the Lomonosov Moscow State University with Prof. A. V. Shevelkov scrutinizing inverse clathrates. Afterwards he was tunneling between Max Planck Institute for Chemical Physics of Solids in Dresden and Fritz Haber Institute of the Max Planck Society in Berlin exploring potential of intermetallic compounds in heterogeneous catalysis supervised by Profs. Yu. Grin and R. Schlögl. In 2008 he moved to Florida State University where he acquired a comprehensive knowledge of magnetism of complex solids under guidance of Prof. M. Shatruk. Kirill started his independent career at UC Davis where he received tenure. Soon after he relocated to Iowa State University. Kirill’s research interests are in the broad field of solid state and materials chemistry with special attention to science of synthesis. Research in his group is focused on synthesis of novel thermoelectric, hybrid magnetic, and low-dimensional materials and exploring their crystal structure, chemical bonding, and physical properties. Understanding the structure-property relationship is a key to the rational design of such materials.