Physical Properties of Nanostructured CdO Films from Alkaline Baths Containing Saccharin as Additive
Nanostructured cadmium oxide (CdO) films were fabricated on glass substrates from alkaline baths containing saccharin as an additive by a successive ionic layer adsorption and reaction (SILAR) method. The effects of saccharin concentration in the bath on the structural, morphological, and optical properties were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence, and Raman spectroscopy. The analyses showed that the surface morphologies, XRD peak intensities, Raman spectroscopy, and photoluminescence properties of CdO films changed with saccharin concentration. From the results, it can be said that morphological characteristic and optical properties of the films could be calibrated by adding various saccharin percentages in the growth bath.
Effect of film thickness on liquefied petroleum gas (LPG) sensing properties of SILAR deposited CdO thin films
Abstract Nanocrystalline cadmium oxide (CdO) thin films of different thicknesses were deposited on a glass substrate by a simple chemical method (successive ionic layer adsorption and reaction, SILAR) based on alternate dipping of the substrate in an alkaline cadmium nitrate solution and double-distilled water containing 1% H 2 O 2 , followed by air heat treatment at 723 K for 5 h. The cadmium oxide thin films were used as sensing layers for liquefied petroleum (LPG) resistive gas sensors. These samples were structurally and morphologically characterized using X-ray diffraction and SEM techniques, respectively. The dependence of LPG sensing properties on the thickness of CdO thin film was investigated. Maximum gas response achieved was 18.75% for the film of thickness 1.5 μm at a fixed gas concentration of 0.08 vol% at 698 K.
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.