Tunable Thermal Conductivity of TiO2 Films of Close-Packed Nanoparticles

We report on the ultra-low thermal conductivity of a series of convectively assembled, anisotropic titania (TiO2 ) nanoparticle films. The TiO2 films are fabricated on aluminum coated glass substrates by flow coating a suspension of ellipsoidal colloidal nanoparticles, resulting in structured films with tailored order. Time domain thermoreflectance is used to measure the thermal conductivity of the TiO2 films. The thermal conductivities of these nanoparticle films are dependent on nanoparticle orientational order and films with more randomly oriented particles exhibit thermal conductivities less than the amorphous limit.Copyright © 2011 by ASME