Doping Effect of Cobalt on Various Properties of Nickel Oxide Prepared by Solution Combustion Method

Abstract

Pure and cobalt-doped (Co-2 to 10 mol%) nickel oxide (NiO) powder samples were prepared by solution combustion method and annealed at 600 °C for 2 h. The crystalline and structural properties were characterised by using X-ray diffraction (XRD) and Raman spectroscopy. Field emission scanning electron microscope (FESEM) and energy-dispersive spectroscopy (EDAX) techniques were used to study the surface morphology and characteristic elements present in samples. Higher value of retentivity (12.20 × 10−2 emu/g) and coercivity (900 Oe) is found for 10 mol% Co-doped NiO, which is much higher than pure NiO. Such properties improve the magnetic memory and hardness of a magnetic material. A decrease in an optical band gap from 2.67 to 2.05 eV was observed for pure and Co-doped (2 to 10 mol%) NiO powder samples, which is quite useful in optoelectronic devices. Maximum value of conductivity (11.23 × 10−6 Ω−1 cm−1) and dielectric constant (204) is found for Co 6 mol%-doped NiO. All the measurements were recorded at room temperature so as to utilise them for device fabrication readily. A significant improvement in magnetic, optical and dielectric properties was observed for NiO with increasing concentration of cobalt, which makes it a better choice for spintronic, optoelectronic, magnetic and storage devices.