Microwave-assisted sol-gel synthesis of Li-Co doped zinc oxide nanoparticles: Investigating the effects of codoping on structural, optical, and magnetic properties for spintronic applications

In this study, we report a cost-effective microwave-assisted sol–gel synthesis of ZnO and Li-Co co-doped ZnO (Zn_1-2xLi_xCo_xO) nanoparticles. The synthesized Zn_1-2xLi_xCo_xO (x = 0, 0.5, 1.0, 2.0 %) nanoparticles were characterized to study their structural, optical, and magnetic properties. The x-ray diffraction analysis led to the identification of the hexagonal wurtzite phase of the prepared samples. The Rietveld refinement of x-ray diffraction patterns was conducted to ascertain the phase purity of the samples. The W-H analysis of the XRD results has been carried out to estimate the several key parameters such as crystallite size, stress, strain and deformation energy density of the samples. The vibrational properties of the prepared nanoparticles were studied by Fourier Transform Infrared spectroscope. The prepared nanoparticles were observed to have a band gap ranging from 3.3 to 3.1 eV as measured by UV–visible spectroscopy. The co-doping of Li and Co elements in ZnO lattice altered its intrinsic properties, particularly its magnetic properties. The vibrating sample magnetometer measurements showed that the nanoparticles exhibit ferromagnetic behavior at room temperature with 2 % dopant concentration. The value of the of the Coercive field, saturation magnetization and remnant magnetization of the ZLC 2.0 sample were found to be 508 gauss, 0.00365 emu/gram and 4.008 × 10^-4 emu/gram, respectively. This makes Zn_1-2xLi_xCo_xO samples a potential candidate for spintronics and optoelectronic device applications.