Molecularly-engineered inorganic nanomaterials and interfaces for novel properties

This is a hybrid seminar.

Speaker: Prof. Dr. Ganpati Ramanath, John Tod Horton Professor of Engineering Department of Materials Science and Engineering at the Rensselaer Polytechnic Institute

Abstract: Integrating nanomaterials, and tailoring heterointerfaces with control over multiple properties, are crucial for diverse applications in electronics and energy. The first part of my talk will discuss a new class of high figure-of-merit bulk thermoelectric materials relevant to solid-state refrigeration. I will show that bulk pellets and thin films comprised of dilutely-doped nanocrystals of pnictogen chalcogenides and oxides exhibit multifold thermoelectric figure of merit increases arising from a combination of nanostructuring isovalent and doping-induced electronic structure changes, leading to low thermal conductivities, and simultaneously high electrical conductivities and Seebeck coefficients, respectively. Electron spectroscopy and theoretical calculations point to key mechanisms including doping-induced carrier concentration control, suppression of antisite defects, and multifold increases in the density of states effective mass. The second part of my talk will describe the use of molecular nanolayers to tailor chemical, mechanical, thermal and electronic properties of metal-ceramic and metal-thermoelectric interfaces germane to device metallization and packaging. I will demonstrate that introducing molecular nanolayers (e.g., organosilanes, thiols, organophosphonates) at inorganic metal-oxide and metal-thermoelectric interfaces can produce remarkable multifold enhancements in interfacial fracture energy during static and dynamic loading, and thermal and electronic transport. Electron and ion beam spectroscopy, and X-ray and electron diffraction show that the property enhancements are due to nanolayer-induced alterations to the inorganic interface chemistry and structure. Key mechanisms include strong bonding, interfacial oxide scavenging, diffusion curtailment, and altered phase formation, all of which can be controlled by molecular termini, length and backbone chemistry. Such molecularly-directed tailoring of interface properties should be attractive for realizing multifunctional electronics devices and energy systems.

Bio: Professor Ramanath received his PhD from the University of Illinois at Urbana-Champaign in 1997. His PhD thesis work won him a Graduate Student Award from the Materials Research Society. After a brief stint in the electronics industry, he joined Rensselaer in 1998 as an assistant professor, promoted as full professor in 2006, and was named John Tod Horton Chaired Professor in 2013. His research focuses on developing a fundamental understanding of structure-processing-property relationships in molecularly-tailored inorganic thin film and bulk nanomaterials and interfaces, and harnessing them for energy and electronics applications.

Ramanath has co-authored 175 journal articles (Google Scholar h-index 51, 10,500+ citations), one book chapter, and holds 9 US patents. He has delivered more than 225 invited/plenary/keynote talks worldwide, and has organized several international symposia and workshops for MRS, AVS and TMS. He co-founded ThermoAura Inc, served as the Director of the NY State Center for Future Energy Systems and an Editor of IEEE Transactions on Nanotechnology (2003-15).

Hosted by MAE professor Gunjan Agarwal