Fig. 4
From: Effect of Morphology and Crystal Structure on the Thermal Conductivity of Titania Nanotubes

a Measured effective thermal conductivity of the titania nanotubes (symbols) versus porosity. The solid lines represent fitting using the effective thermal conductivity model (Eq. 6) with a shape factor of 1.24. b Thermal conductivity over the range of 60–80% porosity for clarity