Sh. Seyyedin, S. M. Hosseini-Golgoo, M. H. Ghezel Ayagh, F. Agend,
Volume 33, Issue 2 (3-2015)
Abstract
In this paper, manufacturing and evaluation of ethanol gas sensors based on thin films of nanostructure tin oxide have been investigated. SnO2 thin films were prepared by both thermal evaporation (type I) and sputtering (type II) methods and heat treated on silicon wafer substrates. Scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD) and energy dispersive spectra (EDS) are employed to study the morphology and chemical composition of the semiconductor samples. Nano-scale grain size with homogenous distribution showed in SEM images of both types. Sensors resistance in air and its variation-transient response toward ethanol vapours (3000 ppm) was determinated. The response of the stable sensors was obtained 3 and 1.18 for type I and type II, respectively. That showes thin film of nanostructure tin oxide by thermal evaporation (type I) has better sensitivity than the other. More effective surface, adsorption sites and base-line resistance due to the more fine grain size in type I nanostructure, are its important reasons. however, it is slow due extensive rise time and fall time.
V. Mohammadpour, M. Soltanieh, Dr. M. Adeli,
Volume 37, Issue 1 (6-2018)
Abstract
In the present study, alkali roasting and oxalic acid leaching were used to extract titanium dioxide from ilmenite, and the effect of ethanol and ascorbic acid on the purity and recovery of titanium dioxide was investigated. In this research, ilmenite was alkali roasted with sodium carbonate for 4 hours at 900˚C. Then, the roasted ilmenite was leached with distilled water for 1 hour at room temperature. Finally, leaching with a mixture of 0.47M oxalic acid and different amounts of ascorbic acid and ethanol was performed at 65˚C. The results showed that using ethanol caused an increase in the amount of recovery and ascorbic acid increased the purity of the extracted titanium dioxide; also, the presence of these two factors at the same time simultaneously increased the amount of purity and recovery of the final product. Eventually, by choosing 0.47M oxalic acid, 0.005M ascorbic acid, and 48% ethanol as the appropriate conditions for leaching media and increasing the leaching time and temperature to 16 hours and 80˚C, it was possible to get titanium dioxide purities which were as high as 93.3% and 90.9%, respectively.
A. Ghasemi, M. R. Loghman Estarki, S. Torkian, G. R. Gordani,
Volume 39, Issue 2 (8-2020)
Abstract
The purpose of this study was to evaluate phase changes and magnetic properties of neodymium doped Ni0.7Zn0.3NdxFe2-xO4 (x = 0, 0.01, 0.03, 0.05, 0.07, 0.10) nanoparticles synthesized by complexing sol-gel method. In this method, triethanolamine (TEA) acted as both a gelling agent and a chelating agent. Samples were characterized by X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). XRD patterns of all synthesized samples revealed the formation of a spinel ferrite phase. Magnetic evaluation of the specimens showed that the Nd0.01 doped sample with a quasi-spherical morphology and particle size of about 60 nm has the highest saturation magnetization of 50 emu/g and coercive force of 103 Oe.
