Effect of dilute co-doping of Ni and Cr on physical properties of TiO2 nanoparticles

Abstract

The present study focuses on the dilute co-doping effect of Ni and Cr ions on the structural, optical, electrical, and magnetic properties of TiO2 nanoparticles synthesized by the sol-gel method. A systematic analysis of the results indicates the formation of anatase phase for dilute concentrations of Ni and Cr ions with no sign of the secondary phases. X-ray diffraction measurements indicate that the average crystallite sizes vary in the range of 15–35 nm while SEM measurements elucidate the spherical nature of these nanoparticles. It has been found that the band gap reduces while temperature-dependent electrical conductivities increase with co-doping of Ni and Cr ions. The room temperature ferromagnetism exists in all the co-doped samples with the maximum saturation magnetization of 0.21 emu/gm. The origin of room temperature ferromagnetism is accounted to the creation of shallow levels with doping or co-doping and the bound magnetic polarons (BMPs) mediated exchange interactions. These observed results govern that Ni and Cr co-doped TiO2 nanaoparticles can be the potential candidates for spintronic applications.