Structural, Optical, and Magnetic Properties of Co-Doped SnO2 Nanoparticles

Cobalt-doped SnO2 nanoparticles with different cobalt concentrations have been prepared using a polyol method, and x-ray diffraction (XRD) analysis and Fourier-transform infrared spectroscopy applied to investigate their structure. The XRD patterns of all the prepared nanoparticles revealed single-phase tetragonal structure. The morphology of the nanoparticles was studied using scanning electron microscopy. Ultraviolet–visible absorbance spectroscopy measurements were utilized to understand the optical properties, revealing the dependence of the bandgap on the cobalt doping concentration. Magnetic measurements revealed that the samples exhibited room-temperature ferromagnetism, which should be an intrinsic characteristic. The origin of the room-temperature ferromagnetism was investigated using vibrating-sample magnetometry and electron spin resonance spectroscopy.