Effect of lattice defects on the structural and optical properties of Ni1-XAgXO (where X=0.0, 0.01, 0.03, 0.05, 0.10 and 0.15) nanoparticles

The Ni1-XAgXO (where X = 0, 0.01, 0.02, 0.03, 0.05, 0.10, and 0.15) nanoparticles are synthesized by sol-gel technique. The effects of Ag-doping in NiO nanoparticle on the structural and optical properties are studied. XRD analysis confirms that the prepared samples are single phase and oxygen deficient in nature. The unit cell volume decreases with the increase in the Ag-doping content. The crystallite size decreases from 23 to 19 nm with increasing the Ag-doping content up to X = 0.10. The strain increases with increase in Ag-doping concentration. FESEM analysis confirms that the pure sample of NiO is quasi-spherical and this shape is deformed as the Ag content increases in the NiO samples. The increase in the agglomeration of nanoparticles with the increase in doping content is also observed. UV-Visible analysis shows that the calculated optical band gap of the pure NiO sample is 3.70 eV which is less than the reported value 4.42 eV of NiO nanoparticles. The optical band gap increases as the Ag-doping content increases in the host NiO lattice. The change in band gap is increased rapidly for the X = 0.01 sample and then become slow for the rest of the samples. FT-IR analysis gives all the information regarding the functional group present in the samples. The effect of disorder created due to Ag-doping in NiO lattice leads to the formation of lattice defects and affects the structural and optical properties, which have been discussed in this paper in detail.