Showing 3 results for Sol-Gel
, , Seyed Lotfollah Sharifi,
Volume 11, Issue 3 (2-2011)
Abstract
In this paper nanoparticles of lithium-cobalt oxide on alumina and silica substrates, by sol-gel method and with citric acid as gelling agent were prepared. The effects of different substrates on size, shape and catalytic effects of nanoparticles were studied. To evaluate the catalytic activity, rate of decomposition of hydrogen peroxide in the presence of any of the samples by measuring the volume of oxygen gas released at the time, was investigated. The X-ray diffraction patterns (XRD), scanning electron microscopy (SEM) and FT-IR spectra confirmed the formation of Co3O4 and LiCoO2 phases
Farhad E.ghodsi, , ,
Volume 12, Issue 4 (11-2013)
Abstract
MgO thin films were prepared using sol-gel method. The influence of annealing temperature on optical, structural properties and surface morphology of the films were investigated using FTIR, UV-Visible and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical constants and thickness of the films were determined by pointwise unconstrained minimization approach. The optical transmittance has decreased with increase of annealing temperature. The refractive index and extinction coefficient of the films increased while the thickness and optical band gap of the films decreased with increasing of annealing temperature. The thickness of film decreased from 635 to 420nm and optical band gap decreased from 4.05 to 4.02eV. The photoluminescence (PL) intensity increased with annealing temperature. XRD patterns demonstrated that the prepared films at 500℃ were amorphous. In addition, the crystal structure of MgO nanopowders which was prepared by sol-gel method was investigated. The crystalline orientation of MgO nanopowders was improved by increasing the sintering temperature. The SEM micrographs show that a homogenous and crack-free film can be prepared at 500°C.
Mohammad Ghazi, Mehdi Hasanshah, , ,
Volume 12, Issue 4 (11-2013)
Abstract
Nickelate with general formula La2-xSrxNiO4 (x≈0.33) were synthesized by the sol–gel method. Then by changing the sintering temperature and growth parameters, particles with various sizes were produced. The crystal structure and physical properties of the prepared samples were investigated by X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FE-SEM) and resistivity measurements from room temperature to low temperatures. The XRD results and investigation of the surface morphology show the lowest temperature to get a single phase tetragonal structure is 920°C. These data confirm the formation of single phase structure in samples sintered at higher temperatures. The particle size increases with increase in sintering temperature. The FE-SEM results show that the particles sizes are in range of 50nm to 2mm. The results of resistivity measurements versus temperature by fourprobe method indicate that the charge ordering transition temperature move to lower temperature with decrease in particle size.
