Simple and Efficient Way of Synthesizing NiO Nanoparticles by Combustion Followed by Ball Milling Method

In this brief article, the synthesis of NiO nanoparticles by combustion followed by ball milling and their characterization are reported. The combustion product was subsequently ball milled for 4 h in a tungsten carbide (WC) jar under 350 rpm, as it showed the mixed phases of NiO and metallic Ni. The thermal behavior of the combustion product examined by thermo-gravimetric and differential thermal analysis (TG-DTA) reveals weight changes (both loss and gain) at four temperatures of 85, 185, 555 and 790 degrees C. The combustion product reveals cubic phase with lattice parameter, a = 0.4179(1) nm and average crystalline size, D of 41 nm, whereas the ball milled materials exhibit the cubic single phase of NiO with a = 0.4176(4) nm and reduced D as 12.36 nm. Both the combustion product and the ball milled materials were extensively characterized by Fourier-transform infrared (FT-IR), near infrared (NIR), photo-luminescence (PL), high resolution scanning electron microscope (HRSEM), and energy dispersive X-ray analyzer (EDX). Unlike other reported nanocrystalline binary oxides such as CeO2, Al2O3, TiO2, MgO and ZnO, the present ball milled NiO nanoparticles reveals very low (<10%) NIR reflectivity in the wavelength range of 650-2500 nm, indicating inferior NIR nature of NiO. The agglomeration of fine particles with the particle size of 14.6 similar to 18.9 nm is seen through HRSEM images on the surface of ball milled NiO nanoparticles.