Talk given by Prof. Ganpati Ramanath Realizing novel nanomaterials and tailored heterointerfaces with control over electrical, thermal and mechanical properties is key for many applications such as electronics devices and energy harvesting. The first part of my talk will discuss the synthesis and properties of a new class of bulk doped bulk nanothermoelectric materials obtained by surfactant-directed sculpting and doping for solid-state cooling and electricity harvesting from waste heat. The second part of my talk will describe the use of single nanolayers of organic coupling agents to tailor multiple properties of soft-hard or organic-inorganic heterointerfaces germane to emergent electronics devices. I will demonstrate a scalable microwave-solvothermal approach to sculpt nanocrystals with controlled shape, size, trace doping and surface chemistry. Bulk pellets made from these nanocrystals exhibit multifold superior figures of merit than their non-nanostructured and non- alloyed counterparts. While nanostructuring leads to ultralow thermal conductivities, doping-induced alterations in defect chemistry and electronic band structure of the materials leads to high electrical conductivities and high Seebeck coefficients. Atomistic and electronic structure level property enhancement mechanisms will be discussed based upon a variety of microscopies, spectroscopies, and density functional theory calculations. I will then describe how interfacial nanolayers of coupling agents with suitably chosen termini are attractive for tailoring the chemical, electrical, mechanical and thermal properties of heterointerfaces. I will demonstrate multifold enhancement in electrical stability, mechanical toughness and thermal conductance by understanding and manipulating the interfacial bond chemistry using molecular nanolayers. I will conclude by discussing the property interrelationships, the enhancement mechanisms, and the utility of using nanomolecular layers to access atomistic details of nanoscopic interfacial phenomena via macro-experiments. Selected references Nature Materials 12, 118 (2013); Nature Materials 11, 233 (2012); Nano Lett. 12, 4523 (2012); Nano Lett. 11(10), 4337 (2011); ACS Nano 4, 5055 (2010); Nano Lett. 10, 4417-22 (2010); Nature 447, 299 (2007); Phys. Rev. B. 83, 035412 (2011); Appl. Phys. Lett. 99, 133103 (2011); Appl. Phys. Lett. 99, 133101 (2011); ACS Appl. Mater. Interf. 2(5), 1275 (2010).

This event is part of the eventgroup INT Talks

Homepage
https://www.int.kit.edu/events.php

Speaker
Prof. Ganpati Ramanath

Rensselaer Polytechnic Institute
Materials Research Center

Organizer
Prof. Dr.-Ing. Horst Hahn
Institute of Nanotechnology (INT)
Karlsruhe Institute of Technology (KIT)
Eggenstein-Leopoldshafen
Mail: horst hahn ∂does-not-exist.kit edu

Targetgroup
Interested / Everyone