Influence of anionic surfactant (SDS) on the structural properties of chromium oxide (Cr2O3) nanoparticles

Abstract

The co-precipitation technique was used to synthesize the surfactant-assisted chromium (III) oxide (Cr2O3) nanoparticles. During the synthesization process, the surfactant sodium dodecyl sulfate (SDS, anionic surfactant) was incorporated. Besides, the surfactant concentration varied from 2 % to 10 % w/w with a step size of 2 %. X-ray diffraction (XRD), Field emission-scanning electron microscope (FESEM), Fourier transform-infrared spectroscopy (FTIR), and Micro-Raman spectroscopy were used to investigate the structural properties of as-prepared nanoparticles. The crystal structure of the as-prepared nanoparticles was confirmed as rhombohedral with space group R-3c by the XRD pattern, FTIR, and Raman spectra. The crystal structure of Cr2O3 nanoparticles remains unaffected with SDS incorporation at various concentrations. However, the crystallite size of synthesized nanoparticles was found to be reduced as the surfactant concentration increased up to a critical concentration value, as determined using the Scherrer equation. The minimum crystallite size of 24.05 nm was obtained at a 6 % w/w SDS concentration. The introduction of lattice strain in the nanoparticles was attributed to the shifting of the XRD peaks, which was evaluated using the Williamson-Hall equation. The intrinsic strain was increased with SDS concentration due to the decrease in average crystallite size. Morphology of pristine and SDS-aided Cr2O3 nanoparticles was found to be nearly spherical in shape.