In this study, a hydrothermal technique was used to synthesize lead sulfide (PbS) and silver (Ag)-doped PbS nanoparticles (NPs) at different concentrations of 20, 40, and 60% of Ag. The small lattice phase changes appeared due to the shifting of diffraction angle peaks toward higher 2θ for samples doped with PbS with increasing Ag content. The analysis of average crystallite size, phase structure, and lattice constant was observed under X-ray diffraction. The value of crystallite size, volume of the unit cell, and porosity (%) were found to increase with the increasing concentration of Ag NPs in PbS. The pure PbS crystallite size is small compared to Ag-doped PbS. The optical characteristics including absorption spectra of the prepared samples were investigated and confirmed by using scanning electron microscope and UV-Vis spectroscopy. The observation of the composition showed that higher doping concentrations of Ag lead to an increase in particle size. Absorption peaks in the UV-Vis spectra corresponding to pure and 20, 40, and 60% of Ag/PbS were observed at different wavelengths of 368, 369, 371, and 372 nm, respectively. Fourier transformation infrared spectroscopy peaks were found in the vibration mode of the ions due to the increment in Ag doping concentrations. These results indicate the possibility of tuning the optical structural properties of Ag-doped PbS through doping various concentrations of Ag NPs. Ag-doped PbS is considered promising future semiconductor nanomaterial, which will enhance the efficiency of photovoltaic device applications.
The First principle study based on Density Function Theory (DFT) was accomplished to explore the electronic bandgap configurations of KNbO 3 by transition metal doping such as Iron [Fe], and Nickel [Ni] using PBE-GGA (Perdew-Burke-Ernzerhof-Generalized Gradient Approximation) for the exchange-correlation potentials. In the current study K 1−x Y x NbO 3 doped with various percentages (12.5%, 25%, 50%, and 75%) of [Ni] and [Fe] metal ions. Different unique properties such as electronic, optical conductivity, and magnetic properties of cubic K 1−x Y x NbO 3 (Y=Fe, Ni) compounds have been calculated through the FP-LAW WEIN2k software within DFT. The bandgap of KNbO 3 can be reduced by doping various metal ions such as [Ni] and [Fe]. The spin up band structures was observed semiconductor but spin down metallic behaviour. The bandgap structure of overall K 1−x Y x NbO 3 (Y=Fe, Ni) compound after doping [Fe] and [Ni] with various concentrations become half metallic compound. Under the DFT scheme, iron [Fe] and nickel [Ni] are reliable as dopants for reducing the bandgap of KNbO 3 . After substituting various impurity concentration (12.5%, 25%, 50%, and 75%) of [Fe] and [Ni] the energy absorption peaks are 8.2 to 8.43eV for K 1−x Y x NbO 3 (Y=Fe, Ni). It is also observed that optical conductivity starting points shift towards the large energy because of bandgap enhancement when the doping concentration (12.5%, 25%, 50%, and 75%) of [Fe] and [Ni] increased in K 1−x Y x NbO 3 (Y=Fe, Ni) compound. Magnetic moment was increasing 1.00153 to 3.02210 μB by the increment of doping [Fe] and [Ni] concentrations. K 1−x Y x NbO 3 (Y=Fe, Ni) compounds are appropriate perovskite oxides materials for promising optical, magnetic and photovoltaic device applications.
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