Dislocation Induced Thermal Diffusivity Tuning of ZnO Hybrid Nanofluids: A Mode Mismatched Dual Beam Thermal Lens Study

The paper delineates the synthesis and development of zinc oxide (ZnO) hybrid nanofluids (HNFs) with different carbon sources (diesel soot (DS) and acetylene black (AB)) to address heat transfer (HT) limitations in thermal systems. Using a highly sensitive mode-mismatched dual beam thermal lens (MDTL) technique, the concentration-dependent thermal diffusivity modifications of the synthesized HNFs are monitored. The method of solution combustion is utilized for the synthesis of ZnO powder. The ZnO-hybrid composites are prepared by solid-state mixing and annealing of ZnO with DS and AB. The structure characteristics of the synthesized hybrid composites are understood through X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The XRD and Raman analyses revealed the structural dislocations and the degree of disorder within the synthesized composites. The optical properties of the samples are revealed through ultraviolet-visible analysis. The MDTL investigation is carried out by preparing HNFs of the samples in ethylene glycol as the base fluid, thus elucidating the effect of lattice dislocations on the thermal behavior of the synthesized HNFs. Thus, the study suggests the potential of lattice dislocations-induced thermal diffusivity tuning ZnO-DS and ZnO-AB hybrid composites for various HT applications.