Study of the Thermal Diffusivity and Optical Properties of Lead Oxide Nanoparticles Annealed at Different Temperatures

In this paper, the crystalline phase change of the oxide lead (PbO) particles during thermal annealing was studied; the process was carried out from 150 °C to 750 °C and monitored by thermal and spectroscopic techniques. The synthesis was carried out using chemical precipitation under atmospheric conditions. Scanning electron microscopy (SEM) micrograph of PbO particles revealed platelet-like morphology. The chemical stoichiometry was obtained by energy-dispersive X-ray spectroscopy, an increased in oxygen concentration was found as annealed temperature increased. An increase in thermal diffusivity was recorded up to 19.36 × 10^–4 cm²·s⁻¹ in a range 450 °C to 650 °C associated to transformation of the crystalline phase tetragonal–PbO to orthorhombic–PbO. The vibration bands of oxide-metallic bonds were revealed by FTIR spectroscopy. The high crystalline quality of PbO was demonstrated by X-ray diffraction. For PbO tetragonal structures the mean diameter of nanocrystals was 42 nm and for orthorhombic was 53 nm, with bandgap of ~ 3.15 and ~ 2.55 eV, respectively.