Effect of co-doped (Ni${}^{2+}$:Co${}^{2+}$) in CdS nanoparticles. Investigation on structural and magnetic properties

Facile chemical precipitation method was used to synthesize Ni (4%) doped and Co (4%): Ni (4%) co-doped CdS nanoparticles. Polyvinylpyrrolidone (PVP) was used as a surfactant to control the particles size and growth rate. The synthesized co-doped sample showed mixed structures of cubic and hexagonal which was confirmed by X-ray diffraction (XRD) study. Average crystallite size is to be 4.2 nm and 3.3 nm for Ni doped and Co:Ni co-doped CdS nanoparticles, respectively. Transmission electron microscopy (TEM) results showed spherical shape with homogeneous particle size distribution of the samples. Due to reduction the particle size, the absorption peak of co-doped CdS shows a significant blue shifting compared to the single metal ion doped CdS nanoparticles. Electron paramagnetic resonance (EPR) spectroscopy was used to study the magnetic g-factor, covalency parameter and magnetic properties of the samples. Anti-ferromagnetic magnetic signal was observed for doped and co-doped samples using Vibrating Sample Magnetometer (VSM) at room temperature. Thermal stability and lattice deformation of the samples were studied using Thermo Gravimetric-Differential Thermal Analysis (TG-DTA). The obtained room temperature based magnetic properties of CdS:Co:Ni nanoparticles demonstrate it could be suitable for spintronic and optoelectronic applications.