Raman spectroscopic investigations of pure, (Mg, Cu), and (Mg, Ru) codoped NiO nanoparticles

The effect of laser heating on the Raman spectra of pure, (Mg, Cu), and (Mg, Ru) codoped NiO nanoparticles was analyzed. Laser power increase (0.15–4.52 mW) caused Raman shifts and intensity variations that indicated stoichiometry and microstructural deviations. Raman spectra of (Mg, Ru) codoped NiO nanoparticles indicated the presence of RuO2 secondary phase. At higher laser power, peaks associated with phonon modes of secondary phases were eliminated. The laser power impacted the structure by expanding the lattice, reducing instability, and substituting Ru into the lattice. Polarization-dependent Raman measurements showed symmetrical nature and preferred crystallization orientation of each sample.