In3+-doped CuS thin films: physicochemical characteristics and photocatalytic property

Semiconducting Indium-doped copper sulfide thin films were deposited on glass substrate by a simple and economical chemical bath deposition technique. The depositions were carried out for 40 min. The electrical studies namely resistivity, resistance, and sheet resistance of CuS and CuS: In were carried out using four-point probe apparatus. The structural, optical, and morphological characterization were studied and compared with those of CuS: In with the bare CuS thin films. XRD studies confirmed that all the prepared thin films have the hexagonal structure of copper sulfide without any secondary phase after doping and the crystallite size was found to be decrease from 69 to 53 nm. Optical absorption analysis of samples shows a red-shift in the band edge of In: CuS thin films relative to CuS film so that the bandgap energy was decreased from 1.95 eV to 1.86 eV. The functional groups present in the CuS and In: CuS samples were confirmed by FTIR and FT-Raman frequency assignments. Morphological studies of CuS and CuS: In are interpreted using SEM and constituents present in the prepared thin films are viewed by EDS. Further the photocatalytic properties of the prepared films were studied by degrading methylene blue (MB) and rhodamine B (RhB) textile dyes. Maximum degradation efficiency achieved by the photocatalyst is to be 95% and 93% respectively for MB and RhB.

     

Grain refining mechanisms in magnesium alloys — An overview

The literature on mechanisms of grain refinement in magnesium alloys is reviewed with regard to two broad groups of alloys: aluminium-bearing and aluminium-free alloys. While a low level zirconium addition significantly reduces the grain size of the aluminium-free alloys, the understanding of mechanisms of grain refinement in aluminium-bearing alloys is poor and in some cases probably confusing due to the interaction between impurity elements and aluminium in affecting the potency of nucleant particles. Mechanisms of grain refinement in magnesium alloys are dealt based on the experimental results in conjunction with microstructural observations. Informations revealed by this approach identify new directions for further research to focus on obtaining an improved understanding of the detailed mechanisms of grain refinement in magnesium alloys.     

On the Optical,Thermal, and Vibrational Properties of Nano-ZnO:Mn,A Diluted Magnetic Semiconductor

Nano-zinc oxide and Mn-doped zinc oxide were synthesized by a chemical process, and the average size of the particles observed was 35 nm for nano-ZnO. Optical and thermal characterizations were carried out by means of photoluminescence and photoacoustic spectroscopy. It was found that nano-ZnO has a thermal diffusivity one order of magnitude larger than bulk ZnO. Similarly, a less explored localized defect mode in ZnO:Mn was studied theoretically and experimentally using FTIR spectroscopy. The localized mode was experimentally found to be 514cm⁻¹, compared to its theoretical value of 502cm⁻¹. These values suggest that the current theory of bulk materials can also be extended to nanosystems and they are consistent with our hypothesis that Mn goes substitutionally as an impurity displacing Zn in nano-ZnO.