Structural, optical and magnetic properties of Ni_1-2xMg_xRu_xO nanoparticles

Abstract

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 deviation from perfect stoichiometry. UV-vis and photoluminescence (PL) spectroscopies are utilized to study the optical properties, where Ni0.84Mg0.08Ru0.1O nanoparticles showed 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.

Effect of Growth and Calcination Temperatures on the Optical Properties of Ruthenium-Doped ZnO Nanoparticles

“…The impurity phase of RuO 2 shows a remarkable rise as Ru doping increases, caused by the large ionic difference between the dopant Ru 3+ (0.068 nm) and the host Zn 2+ (0.0074 nm) [36,37]. This large ionic difference prevents the dopant from incorporating into the host atoms leading to an increase in the crystallite size, as depicted in Table 1 [38]. From Equations ( 4) and ( 5), the specific surface area and the dislocation density are inversely proportional to the crystallite size.…”