Nickel OxideNanoparticles with and without Metallic Doping: Synthesis Structure, Conductivity, Dielectric, and Optical Properties

NiO and NiO metal-doped nanoparticles (NPs) were synthesized using a two-step process. These NPs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and nitrogen adsorption desorption. The cubic structure of the NiO was validated from the similarity of the X-ray diffraction peaks and that all the metallic dopants (Cu and Cr) were stabilized in their sites within NiO structure. TEM revealed the configuration whereby the NiO NPs were arranged side by side and aligned along the same direction, forming a small array shaped agglomerates with around 500 nm length and 50–70 nm diameter. Adsorption-desorption isotherms for N2 indicated that NiO NPs could be characterized by type IV isotherms with a hysteresis loop at relative pressures between 0.5 and 1.0. The Hysteresis loop's pattern was of H2 type which is a characteristic pattern for inckbottle shaped pores. Dielectric properties and electrical conductivity were conducted at 25 °C – 110 °C and within the frequency range between 100 Hz and 0.3 MHz. Optical properties (e.g. refractive index, optical energy gap, the molar refractivity) for NiO, NiO:Cu, and NiO:Cr NPs were investigated. The data reveal that, the energy gap and the metallization criterion were the lowest for the NiO:Cu NP sample. On the contrary, the refractive index, molar refractivity were the highest for NiO:Cu NP sample.