Thermal lens study of absolute porosity in ceria: A Sankar–Loeb model approach

Abstract

The present work divulges the potential of thermal lens technique for analyzing the absolute porosity of a material in nanofluid using the recently proposed Sankar–Loeb model. The ceria nanoparticles synthesized by co-precipitation technique are subjected to morphological and structural characterizations. The study reveals that particle size and thermal diffusivity increase with annealing temperature. The nanocavities formed during the agglomeration of nanoparticles result in closed pores which give rise to absolute porosity that is probed by the thermal wave propagation (or thermal diffusivity) study. The enhancement in the particle size enhances the closed pore volume in the sample resulting in increased absolute porosity. Thus, the TL technique makes the analysis of closed pores possible through the absolute porosity study, which is not possible with the conventional BET (Brunauer–Emmett–Teller) technique.