Synthesis and characterization of Cd

Cd1−xZnxS (with x = 0, 0.01, 0.03, 0.05 and 0.1) nanopowder were synthesized by chemical precipitation method under N2 atmosphere at room temperature. Cd1−xZnxS nanostructured thin films were deposited on the glass at 450 °C by spraying the colloidal suspension of the Cd1−xZnxS nanoparticles. Optical and structural properties of both nanostructures were investigated. The prominent peaks of X-ray diffractions (XRD) of samples indicate that the Cd1−xZnxS crystalline grain size in the nanostructured thin film is larger than the Cd1−xZnxS nanoparticles in the nanopowder, due to growing of the grains, originated from high temperature of the substrate. UV-Vis absorption spectra show that both Cd1−xZnxS nanostructures have smaller band edge wavelength in comparison with bulk samples. There is also an increase in blue shift value of the band gap of both Cd1−xZnxS nanostructures, with increasing x, which can be attributed to Burstein-Moss effect. It was found that the variation of the band gap of ZnxCd1−xS nanopowder and nanostructured thin films with Zn concentration are approximately linear with similar slopes. Photoluminescence (PL) spectra indicated that the emission peaks of both the samples are shifted toward the shorter wavelengths with increasing Zn+2 ions

Effect of Sn concentration on optical and structural properties of Pb

Pb1-xSnxS nanopowder with different Sn concentrations (x = 0.02, 0.05, 0.10, 0.20, 0.50 and 1.00) were synthesized by chemical precipitation route under N2 atmosphere. The samples were characterized by X-ray diffraction(XRD), UV-vis absorption spectra and photoluminescence (PL) spectra. The XRD results show that the samples with 0 ≤ x ≤ 0.2 have cubic (fcc) structure with diameter in the 12.8–24 nm range. The sample with x = 0.5 has orthorhombic structure with a diameter of 9.2 nm. The band gap (or absorption edge) of PbS exhibits a large blue shift when the crystallite size is reduced to nanometer scale, from 0.4 eV in bulk samples to 1.8 eV in nanosize samples, which can be related to large Bohr excitonic radius of PbS nanoparticles. PL emission spectra of Pb1-xSnxS in red region excited at 315 nm, for x = 0 showed three broad peaks located at 776.5 nm, 809 nm and 826 nm which due to the defect densities and for x = 0.02, 0.05, 0.10 there are two relatively strong emission peaks located at 786 nm and 823 nm which can be related to transition from sulfur vacancy level and Sn+2 ion level respectively