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. تفاصيل المقالة

In this work, structural and magnetic properties of LaMnO3+δ compound prepared by citrate precursor method and annealed in presence of oxygen are investigated. The structural characterization of LaMnO3+δ by X-ray powder diffraction and using X’pert package and Fullprof program is evidence for a rhombohedral structure (R-3c space group) confirmed by FTIR measurement. The magnetic measurements show a super-paramagnetic behavior of LaMnO3+δ due to low values of coercive field and romance magnetization and also high value of saturation magnetization. In addition, a comparative study of the crystallite size of the compounds obtained from powder XRD is reported. The Williamson-Hall analysis, size-strain plot and Halder-Wagner methods were used to study the individual contributions of crystallite sizes and lattice micro-strain on isotropic line broadening of all the reflection peaks of the LaMnO3+δ compound. The results show the Halder-Wagner method is more accurate, with all data points touching the fitting line better than the other methods. The crystallite sizes estimated from XRD (30.86 nm) and particle size estimated from TEM method (36 nm) and also the magnetic core size (33.6 nm) estimated from magnetic measurement agree well, while a little difference reflects a spherical shape of the nanoparticles. تفاصيل المقالة

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. تفاصيل المقالة

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. تفاصيل المقالة

In the present work CuBi2O4 nano-spinel has been synthesized via mild hydrothermal method at 180°C for 10 h. The synthesized nanomaterials were characterized by several techniques to emphasis the structure and properties of produced materials. The crystal structure was investigated by X-ray powder diffraction method and the values of refined unit cell volume and the structure properties were studied by using the Rietveld analysis is done using fullprof program. The results shew the formation of tetrahedral structure with space group P4/ncc for this sample. Also, the morphologies of the synthesized materials were figured out by field emission scanning electron microscope (FE-SEM). According to the FESEM images, several nano cubic form particle grew on micro spherical particles. As well, the catalytic performance of obtained CuBi2O4 was studied in Biginelli reaction. The reaction conditions of this study optimized by experimental design method. This experiment stablished high catalytic performance of copper bismuth oxide in compare with some other metal oxide catalysts.Also, the results shew this product is reusable homogenous catalyst. تفاصيل المقالة

In this work, the structural and elastic moduli properties of ZnFe2O4, Zn0.5Cu0.5Fe2O4, and Ni0.3Cu0.2Zn0.5Fe2O4 ferrites prepared by citrate method have been investigated. The structural characterization of the samples is evidence for a cubic structure with Fd-3m space group. The Halder-Wagner analysis was used to study crystallite sizes and lattice strain and also stress and energy density. The cation distribution for each composition has been suggested. The experimental and theoretical lattice constants were found to be in good agreement with each other confirming the agreeability of the suggested cation distribution. The force constants for tetrahedral and octahedral sites have been determined by infrared spectral analysis. The increase in force constants of ZnFe2O4 nanoparticles compared to other samples suggests the elastic properties of this sample is better than the other samples. The values of Young’s modulus, rigidity modulus, bulk modulus, Debye temperature have been determined. In addition, using the values of the compliance sij obtained from elastic stiffness constants, the values of Young’s modulus and Poisson’s ratio along the oriented direction have been calculated for the samples. Consequently, we can conclude the ZnFe2O4 nanoparticles could be more useful in industry applications because of their elastic properties compared to other samples. تفاصيل المقالة

In this paper, microstructure and swelling behavior of five superabsorbent hydrogels have been investigated. These samples were prepared by dispersing watermelon shell powder (WSP) and cucumber shell powder (CSP), mixture bentonite and WSP, mixture bentonite and CSP, zeolite (Z) bentonite (B), into poly(acrylamide-co-acrylic acid) (P) backbone in an aqueous medium. The nanocomposites have been synthesized through chemical cross-linking by polymerization technique using N,N-methylenebis acrylamide as a cross-linker and potassium persulfate as an initiator in a simple aqueous environmental conditions. The nanocomposite hydrogels named as P-WSP-CSP، P-WSP-B، P-CSP-B، P-Z، P-B, respectively. These superabsorbent nanocomposites were characterized by X-ray diffraction, Fourier transform infrared and field emission-scanning electron microscope measurements. The water absorption and desorption of the superabsorbent nanocomposites have also been studied. Our findings show that very high water absorption and lower drying rate of P-CSP-B are attributed to higher porous surfaces observed in FE-SEM images. The results show the superabsorbent hydrogels based on CSP represent very high water absorbency capacity and water retention ability that make them suitable for technology applications. تفاصيل المقالة

In this work, the structural and elastic moduli properties of ZnFe2O4, Zn0.5Cu0.5Fe2O4, and Ni0.3Cu0.2Zn0.5Fe2O4 ferrites prepared by the citrate method have been investigated. The structuralcharacterization of the samples is evidence for a cubic structure with Fd-3m space group. TheHalder-Wagner analysis was used to study crystallite sizes and lattice strain and also stressand energy density. The cation distribution for each composition has been suggested. Theexperimental and theoretical lattice constants were found to be in good agreement with eachother confirming the agreeability of the suggested cation distribution. The force constantsfor tetrahedral and octahedral sites have been determined by infrared spectral analysis. Theincrease in force constants of ZnFe2O4 nanoparticles compared to other samples suggests theelastic properties of this sample is better than the other samples. The values of Young’s modulus,rigidity modulus, bulk modulus, Debye temperature have been determined. In addition,using the values of the compliance sij obtained from elastic stiffness constants, the values ofYoung’s modulus and Poisson’s ratio along the oriented direction have been calculated for thesamples. Consequently, we can conclude the ZnFe2O4 nanoparticles could be more useful inindustrial applications because of their elastic properties compared to other samples. تفاصيل المقالة

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. تفاصيل المقالة

In this paper, microstructure and swelling behavior of five superabsorbent hydrogels have been investigated. These samples were prepared by dispersing watermelon shell powder (WSP) and cucumber shell powder (CSP), mixture bentonite and WSP, mixture bentonite and CSP, zeolite (Z) bentonite (B), into poly(acrylamide-co-acrylic acid) (P) backbone in an aqueous medium. The nanocomposites have been synthesized through chemical cross-linking by polymerization technique using N,N-methylenebis acrylamide as a cross-linker and potassium persulfate as an initiator in simple aqueous environmental conditions. The nanocomposite hydrogels named as P-WSP-CSP، P-WSP-B، P-CSP-B، P-Z، P-B, respectively. These superabsorbent nanocomposites were characterized by X-ray diffraction, Fourier transforms infrared and field emission-scanning electron microscope measurements. The water absorption and desorption of the superabsorbent nanocomposites have also been studied. Our findings show that very high water absorption and lower drying rate of P-CSP-B are attributed to higher porous surfaces observed in FE-SEM images. The results show the superabsorbent hydrogels based on CSP represent very high water absorbency capacity and water retention ability that make them suitable for technology applications. تفاصيل المقالة

In the present work CuBi2O4 nano-spinel has been synthesized via mild hydrothermal methodat 180°C for 10 h. The synthesized nanomaterials were characterized by several techniquesto emphasis the structure and properties of produced materials. The crystal structure wasinvestigated by X-ray powder diffraction method and the values of the refined unit cell volumeand the structure properties were studied by using the Rietveld analysis is done using Fullprofprogram. The results shew the formation of tetrahedral structure with space group P4/ncc for this sample. Also, the morphologies of the synthesized materials were figured outby field emission scanning electron microscope (FE-SEM). According to the FESEM images,several nano cubic form of particles grew on micro spherical particles. As well, the catalyticperformance of obtained CuBi2O4 was studied in Biginelli reaction. The reaction conditions ofthis study optimized by experimental design method. This experiment stablished high catalyticperformance of copper bismuth oxide in compare with some other metal oxide catalysts. Also,the results shew this product is reusable homogenous catalyst. تفاصيل المقالة

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. تفاصيل المقالة