Structural, optical and magnetic properties of Ni1-2xMgxRuxO nanoparticles

Ni1-2xMgxRuxO (x = 0, 0.005, 0.01, 0.02, 0.04 and 0.08) nanoparticles were synthesized via the coprecipitation method. The prepared NiO nanoparticles are characterized by thermogravimetric analysis (TGA) that reveal the successful codoping and assure the thermal stability of the samples beyond 550 C. X-ray powder diffraction (XRD) confirms the formation of the NiO cubic structure with RuO2 secondary phase that appears at high codoping concentrations. As the codoping concentration increases, the lattice parameter increases and crystallite size decreases. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) show slightly agglomerated pseudo-spherical nanoparticles. Energy dispersive x-ray (EDX), X-ray photo-induced spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy reveal the elemental composition and deviation from perfect stoichiometry. UV-vis and photoluminescence (PL) spectroscopies are utilized to study the optical properties, where Ni0.84Mg0.08Ru0.08O nanoparticles show the highest direct band gap energy and lowest Urbach energy and electron-phonon interaction. Vibrating sample magnetometer (VSM) shows single domain nanoparticles, such that the coercivity and magnetocrystalline anisotropy decrease as the size decreases. The bound magnetic polaron model was utilized to investigate the weak ferromagnetism exhibited by the prepared Ni1-2xMgxRuxO nanoparticles.