Our paper,  “Ultra-low thermal conductivity of ellipsoidal TiO₂ nanoparticle films ”  was recently published in Applied Physics Letters (Applied Physics Letters 99, 133106 (2011)).  In this work, we show that films comprised of close-packed titania nanoparticles exhibit thermal conductivities that are lower than the theoretical minimum limit and show a dependency on nanoparticle orientation and alignment.

Our paper, “Ultra-low thermal conductivity of ellipsoidal TiO2 nanoparticle films,” was just accepted into Applied Physics Letters.  In this work, we show that the orientational order of ellipsoidal titania nanoparticle films can affect the thermal transport.  In addition, the thermal conductivities of these films are lower than amorphous titania.  This work was performed in collaboration with Professor Eric Furst’s group at University of Delaware and Leslie Phinney and Anne Grillet at Sandia National Laboratories.

Abstract

We report on the thermal conductivity of a series of convectively assembled, anisotropic titania (TiO2) nanoparticle films. The TiO2 films are fabricated by flow coating a suspension of ellipsoidal colloidal nanoparticles, resulting in structured films with tailored orientational order. The thermal conductivities depend on nanoparticle orientation and exhibit thermal conductivities less than amorphous TiO2 films due to inter-nanoparticle boundary scattering. This nanoparticle ordering presents a unique method for manipulating the thermal conductivity of nanocomposites.

Our paper,  “Influence of anisotropy on thermal boundary conductance at solid interfaces”  was recently published in Physical Review B (Physical Review B 84, 125408 (2011)).  In this work, we show that the crystalline orientation can affect the thermal boundary conductance across solid interfaces when one of the solids comprising the interface has anisotropic phonon properties.

We are excited to welcome Brian Foley to the Lab, and to UVA!  Brian received his M.S. and B.E. degrees in Electrical & Computer Engineering from Worcester Polytechnic Institute in 2009 and 2007, respectively, where he focused on non-destructive evaluation technologies for General Motors.  Prior to joining the our group, he worked for two and a half years at Virginia Diodes, Inc. making vector network analyzer (VNA) extension modules for calibrated S-parameter measurements from 75-1100GHz.  As a PhD student, Brian will research the nano-scale heat transfer in materials used in RF & microwave semiconductor devices.