Thermo chemical stability of cadmium sulfide nanoparticles under intense pulsed light irradiation and high temperatures

Thermo chemical stability of CdS nanoparticles under an Intense Pulsed Light from a xenon flash lamp and high temperature X-ray Diffraction (XRD) were investigated. The CdS nanoparticles were obtained with a chemical bath method. The CdSO4 (0.16 M) solution was added to an NH3 (7.5 M) solution under constant stirring. Afterwards, a thiourea (0.6 M) solution was added. The bath temperature and pH were maintained at 65 °C and 10, respectively and the mixture was stirred constantly until a solid precipitate of yellow CdS was produced. Its microstructure was investigated with Scanning Electron Microscopy, and its electronic properties were determined by UV–visible and Photo luminescence Spectroscopy. The microstructure of the sintered CdS nanoparticles, obtained the high temperature XRD, was investigated with EDAX and X-ray micro Tomography. In addition, high temperature XRD and Themogravimetric Analysis tests were conducted over the samples. The CdS nanoparticles’ crystallinity increased with the irradiation exposure and they were thermally stable until 600 °C in argon atmosphere. However new phases start to appear after annealing at 400 °C for 30 min in air atmosphere. The main contribution of this paper was to investigate the stability of CdS nanoparticles under intense light and high temperature conditions. It was found that the number of irradiation shots conducted with the IPL technique increased the crystallinity of the CdS, by increasing the CdS nanopillars formation. A simple mechanism of ultra fast melting and cooling like quenching has been proposed to explain the phenomenon. It is also shown than at temperatures higher than 600 °C, different oxides appeared, while temperatures higher than 900 °C had a complete degradation of the CdS.