Please see seminar notice for tomorrow below: MATERIALS SCIENCE AND ENGINEERING SEMINAR Thermal Conductivity of Silicon and Silicon/Germanium Core/Shell Nanowires By: Matthew Cherukara Ph.D. Prelim Examination Part I Advisor: Prof. A. Strachan ABSTRACT Thermoelectricity, the conversion of temperature differences to differences in electrical potential and vice versa, has been known since the early 19th century from work done by Seebeck, Peltier and Thomson. Their widespread use is still limited, however, by the low efficiencies of the best thermoelectric materials available today. The thermoelectric efficiency, described by a figure of merit (ZT), is a function of both the thermal and electronic properties of the material. Recent attempts to improve the ZT of materials have focused on the reduction of thermal conductivity without adversely affecting the electronic conductivity of the material. Si/Ge core/shell nanowires show promise, with the reduction in thermal conductivity coming from the increased phonon scattering at the interfaces and at the free surface. The proposed use of an amorphous Ge coating on crystalline Si and the use of core/shelled nanotubes could further lower the thermal conductivity, possibly improving the efficiency enough for this class of materials to compete with traditional systems of cooling and power generation. Date: Wednesday, March 20, 2013 Time: 1:00 P.M. Place: ARMS 1028 Lisa Stacey Secretary/Development Assistant Purdue University School of Materials Engineering 765/494-4100