Green synthesis of cerium oxide, Co-doped cerium oxide nanoparticles and its dielectric properties

Abstract

In this article, we have synthesized CeO2 and Co-doped CeO2 nanoparticles (NPs) using the sol–gel method in a greener route by using Acacia Concinna fruit extract as a natural surfactant. Different doping concentrations of Ce1-xCoxO2 (where x = 0.02, 0.04, and 0.06 w/w) were prepared by adding varying concentrations of cobalt nitrate to ceric ammonium nitrate in a stoichiometric ratio. The characterizations were done by different techniques like XRD, SEM, Raman spectroscopy, and FT-IR. XRD pattern shows a single-phase cubic fluorite type structure for the CeO2 and Co-doped CeO2 NPs. The crystallite sizes calculated from the XRD pattern were 22.7 nm for CeO2 NPs and for Co-doped CeO2 NPs, it increased from 38.15 nm to 46.04 nm, when the concentration of cobalt doping was increased from 2 % to 6 %. The formation of the cubic phase of CeO2 in both pure and Co-doped CeO2 NPs was further confirmed through Raman spectroscopy, which signified the vibrational mode of cubic fluorite type structure of CeO2 NPs at 462 cm−1. SEM images illustrated a porous structure for both the doped and un-doped NPs, the porosity being more for Co-doped CeO2 NPs. FT-IR analysis showed characteristic absorption bands for Co-O-Ce and CO at 1118 cm−1 and 2924 cm−1, respectively. The effects of the composition of the dopant on the dielectric properties of Co-doped CeO2 NPs were studied. The dielectric properties of the as-synthesized NPs vary with the percentage of cobalt doping.