Temperature-dependent studies of nickel oxide nanoparticles prepared by simple co-precipitation method.

A facile co-precipitation process is used to create nickel oxide (NiO) nanoparticles, which are subsequently annealed at various temperatures starting from 250°C, 300°C, 400°C, and 500°C and distinguished by X-ray diffraction, Raman spectroscopy, TGA/DSC analysis, and Fourier Transform Infrared spectroscopy. The face-centered cubic structure of prepared NiO nanoparticles with average crystallite sizes varying from 3 to 15 nm was revealed by X-ray patterns with increasing annealing temperature. The Raman spectra of the samples revealed the characteristic NiO modes of one-Phonon (1P), two-Phonon (2P), and two-Magnon (2M). The prepared samples' surface optical (SO) phonon modes showed a blue shift and broadening with decreasing size. The 2M mode was present in samples annealed at 500°C but disappeared in samples annealed at lower temperatures. This is due to the crystal lattice's Ni2+ vacancy-induced defects and disorder. The bands in the FTIR spectra of prepared samples associated with Ni-O and O-H stretching vibrations confirmed the formation of NiO nanoparticles. With increasing annealing temperatures, a blue shift was observed. [ABSTRACT FROM AUTHOR]