Papers by Keyword: Lead Sulfide

Abstract: Micro-dendrite structure lead sulfide was synthesized by a simple hydrothermal method at 180°C using lead acetate and thiourea as raw materials. The obtained powder sample was characterized by XRD, TEM and ED. Photocatalytic performance of the sample was investigated by the degradation of Congo red under visible light. The sample shows high photocatalytic activity and the charge-carrier of the hole plays an important role in the photodegradation process.

Abstract: PbS quantum dots (QDs) were prepared through a two-phase approach and an aqueous method respectively. The reaction conditions of the two-phase approach were mild and highly controllable, but the as-prepared QDs were capped with oleic acid. Although the PbS QDs prepared by the aqueous method did not exhibit excellent photoluminescence properties, it was more facile and environmentally friendly, and furthermore the resulting PbS QDs were more promising in biological labeling without ligand exchange. We have investigated the absorption and luminescent properties of QDs prepared by the two methods. The results showed that the absorption shoulder of oil soluble PbS QDs was at 580nm and water soluble PbS QDs was at 600~700nm. And the emission peaks in the photoluminescence spectra were at 755nm and 970nm, respectively. XRD analysis confirmed that the PbS QDs were cubic phase. The TEM results showed that the size of both types of PbS QDs was smaller than the excitons Bohr radius (18nm).

Abstract: Large area (13mm*13mm) PbS thin films with (200) preferred orientation were prepared by chemical deposition. The optical properties of PbS films with annealing treatment in various forming gases with different ratio of nitrogen-oxygen (100ml/min of N₂&O₂(3:1), 100ml/min of N₂&O₂(2:1), 100ml/min of N₂&O₂(1:1), 50ml/min of O₂) were deeply analyzed. X-ray diffraction (XRD), scanning electron microscope (SEM), high and low temperature test chamber and other test methods for photosensitivity were used to investigate the structure and photoelectric properties of PbS films. The results showed that with proper amount of oxidation (when nitrogen-oxygen ratio was 1:1), the impurity barrier tended to fully grow, impurity activation energy increased to 0.314eV, dark resistance reached up to 30.2MΩ, and the photoconductive sensitivity of PbS thin film under this process was about 4 times larger compared with air annealing. According to the analysis of XRD patterns and surface morphologies of films, it can be seen that nitrogen in this process was not only to prevent PbS thin films from excessive oxidation, but also inhibited the formation of surface defects and enhanced the stability of PbS device.

Abstract: Hydrothermal sulfidation of pure white lead with elemental sulfur has been studied in the present paper. The variables considered in the study were temperature, time, particle size and elemental sulfur fraction in the reacting mixture. Temperature and time were the most two important factors, with an increase in temperature and holding time the sulfidation extent of lead improved greatly and the constituent of products changed a lot. At temperatures above 140°C, PbS and PbSO4 were the only stable reaction products in the sulfidation of white lead. The experimental data indicated that under the hydrothermal conditions with a particle size of -58+48 μm and sulfur fraction in reacting mixture of 8% at 140 °C for 90 min, and 86% of lead sulfidation extent was achieved.