Structural features of La(1-x)SrxMn0.5Co0.5O3 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) nano-particles were investigated using X-ray powder diffraction and FT-IR spectroscopy. The characterization of compounds by X-ray powder diffraction and using Fullprof program show a cubic structure (Pm3m space group) for x = 0.0 and a rhombohedra structure (R-3c space group) for the Sr substituted La(1-x)SrxMn0.5Co0.5O3 samples. Crystallite size and unit cell parameters decrease with Sr substitution. The electrical conductivity of the samples in oxidizing (air) and reducing atmosphere (6%CO in nitrogen) and also band gap of the samples has been investigated to interpret the performance of samples. Results show that their behavior increases non-uniformly with increase in Sr substitution. An increase of Sr substitution up to 0.5 increases the performance of the samples and an optimal catalytic activity in the low-temperature conversion of CO to CO2. It is mainly attributed to a decrease of the crystallite size. پرونده مقاله

La0.55Ca0.45A0.5Co0.5O3(A = Mg, Mn) nanoparticles prepared by citrate method were characterized using X-ray diffraction measurement, transmission electron microscopy, Fourier transform infrared and UV-Vis spectroscopy. The structural analysis using X’Pert package and Fullprof program is an evidence for the presence of the perovskite structure. The calculated value of crystallite size, particle size and band gap energy of La0.55Ca0.45Mg0.5Co0.5O3 is much less than La0.55Ca0.45Mg0.5Co0.5O3. The photocatalytic activity of the product was studied for degradation of an aqueous solution of methyl blue under solar condition. The effects of three operational parameters including irradiation time, pH, and the catalyst amount on the dye degradation were analyzed using optical absorption spectra. The degradation efficiency of MB solutions in the presence of 10 mg La0.55Ca0.45Mn0.5Co0.5O3 nanoparticles under visible light indicate to be higher than La0.55Ca0.45Mg0.5Co0.5O3 nanoparticles. 96 % degradation is obtained in an aqueous solution at pH = 2.33 and containing 30 mg La0.55Ca0.45Mg0.5Co0.5O3 catalyst after 30 minutes. پرونده مقاله

Perovskite-type oxides of LaFe(1+x)O(3+δ) (x = 0.0, 0.2, 0.5 and 0.7) were synthesized by citrate sol–gel method to ensure the formation of nanosized perovskites. The physicochemical properties of these LaFe(1+x)O(3+δ) materials were characterized by thermal gravimetric/differential analyses, Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron and transmission electron microscopies, ultraviolet-visible spectroscopy, Brunauer Emmett Teller nitrogen absorption, electrical conductivity measurements and magnetic studies. Catalytic performances of the prepared materials were evaluated for the carbon monoxide oxidation. Trace of FeCO3 and Fe2O3 phases were detected over the perovskites of LaFe(1+x)O(3+δ) with excess iron (x > 0) using the XRD and FT-IR studies. The SEM results demonstrate the formation of non-spongy particles. The magnetic measurements show a charge ordering transition at ~230 K for LaFe1.2O(3+δ) perovskite. The weak long range charge ordering of Fe2+/Fe3+ destroys over an increase in the content of the phases other than LaFeO3 perovskite. The best σox/σRed and the lowest Ec is accounted for the more suitable path for catching and giving of the gas phase oxygen over LaFe1.2O(3+δ) nanoperovskite; meaning most favorable redox properties. The light off temperature of the CO oxidation in terms of reducibility studies is decreased about 70°C over crystalline LaFe1.2O(3+δ) catalyst. پرونده مقاله

Perovskite-type oxides of LaFe(1+x)O(3+δ) (x = 0.0, 0.2, 0.5 and 0.7) were synthesized by citrate sol–gel methodto ensure the formation of nanosized perovskites. The physicochemical properties of these LaFe(1+x)O(3+δ)materials were characterized by thermal gravimetric/differential analyses, Fourier transform infraredspectroscopy, X-ray powder diffraction, scanning electron and transmission electron microscopies,ultraviolet-visible spectroscopy, Brunauer Emmett Teller nitrogen absorption, electrical conductivitymeasurements and magnetic studies. Catalytic performances of the prepared materials were evaluatedfor the carbon monoxide oxidation. Trace of FeCO3 and Fe2O3 phases were detected over the perovskitesof LaFe(1+x)O(3+δ) with excess iron (x > 0) using the XRD and FT-IR studies. The SEM results demonstratethe formation of non-spongy particles. The magnetic measurements show a charge ordering transitionat ~230 K for LaFe1.2O(3+δ) perovskite. The weak long range charge ordering of Fe2+/Fe3+ destroys over anincrease in the content of the phases other than LaFeO3 perovskite. The best σox/σRed and the lowest Ecis accounted for the more suitable path for catching and giving of the gas phase oxygen over LaFe1.2O(3+δ)nanoperovskite; meaning most favorable redox properties. The light off temperature of the CO oxidationin terms of reducibility studies is decreased about 70°C over crystalline LaFe1.2O(3+δ) catalyst. پرونده مقاله

In this paper, La0.55Ca0.45A0.5Co0.5O3(A=Mg, Mn) nanoparticles were synthesized by citratemethod. The samples were characterized using the techniques of using X-ray diffraction(XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and UVVisspectroscopy. The structure was analyzed by Rietveld fitting of the XRD pattern by usingX’Pert package and Fullprof program, these shows that the samples have perovskite structure.The calculated values of crystallite size, particle size and band gap energy of La0.55Ca0.45Mg0.5Co0.5O3 are much less than La0.55Ca0.45Mg0.5Co0.5O3. The effects of three operational parametersincluding irradiation time, pH, and the catalyst amount on the photocatalytic activity ofthe product on the degradation of methyl blue (MB) under solar condition were studied. Thephotocatalytic degradation efficiency of MB solution over La0.55Ca0.45Mn0.5Co0.5O3 nanoparticlesis higher than that over La0.55Ca0.45Mg0.5Co0.5O3 nanoparticles. 96 % degradation is obtainedin an aqueous solution at pH=2.33 and containing 30 mg La0.55Ca0.45Mg0.5Co0.5O3 catalystafter 30 minutes. پرونده مقاله