Effect of Co-doping in V2O5 nanoparticles synthesized via a gelatin-based sol-gel method

Abstract

The V2-xCoxO5 nanoparticles with Co concentrations up to x = 0.2 were synthesized via a rather facile sol-gel route in gelatin medium. The effect of Co substitution was investigated on the microstructural, optical and magnetic characteristics of the synthesized particles using X-ray diffractometer, transmission electron microscope, UV–vis diffuse reflectance spectroscope and vibrating sample magnetometer. The results showed that the synthesized particles consist mainly of crystalline α-V2O5 phase. The orthorhombic unit cell expands and the particle size increases from about 34 to 49 nm with Co content. It was found that the synthesized V2O5:Co nanoparticles are direct band gap semiconductors whose band gap energies obtained in the range of 2.92–3.09 eV are controlled by the surface and interface effects rather than the chemical composition. The low Co substitution destroys the ferromagnetic nature of the pristine V2O5 sample by decreasing the oxygen vacancies being the probable origin of the observed ferromagnetism. However, the higher Co concentrations go for its restore as a result of the dominant effect of their magnetic moment.