T (+98) 23 352 20220
Email: international@du.ac.ir
Damghan University
University Blvd, Damghan, IR
Ahmad Gholizadeh
Assistant Professor of Condensed Matter Physics
Biography
Ahmad Gholizadeh was born in 1980 and earned his Ph.D in 2011 in Condensed Matter Physics from Ferdowsi University of Mashhad (Iran). Since 2012 at present, his major fields of study are related to Nanomaterials, Nanocomposites for Nanosciences and Nanotechnology.
Education
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Ph.D. 2006-2011
Solid State Physics
Thesis: Magnetoelastic properties of RE3 (Fe, Co, M)29 (RE = Tb, Y, Ce, Pr and M = V, Cr, Ti) alloys
Supervisor: Prof. Naser Tajabor
Ferdowsi University of Mashhad, Mashhad, Iran
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M.Sc.2003-2006
Solid States Physics
Thesis: Influence of N2-and Ar-ambient annealing on the physical properties of SnO2:Co transparent conducting films prepared by spray pyrolysis technique
Supervisor: Prof. Mohammad Reza Alinejad
Ferdowsi University of Mashhad, Mashhad, Iran
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B.Sc. 1999-2003
Solid States Physics
Project: Determination of Miller Indices: Rotational Crystal Method
Supervisor: Prof. N. TajaborFaculty of Science, Kharazmi University, Tehran, Iran
Selected Publications
DOI: 10.1016/j.ceramint.2018.09.158
In this paper, Mn0.3−xMgxCu0.2Zn0.5Fe3O4 (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30) nanoparticles were prepared by the nitrate-citrate technique at low temperature. The structural, microstructural, magnetic and elastic properties of the samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, Transmission electron microscopy, field emission-scanning electron microscopy and vibrating-sample magnetometer at room temperature. Rietveld refinement of the XRD patterns indicated the formation of the single phase cubic spinel structure (space group Fd-3m) without any detectable impurity phase in all the samples that also was confirmed by FTIR studies. The lattice parameter is found to increase non-monotonically with an increase in Mg ion concentration. Also, the bond lengths and bond angles (A and B sites) of the studied ferrites were calculated by the refining of the XRD data. The values of the crystallite size decrease with increasing micro-strain (and conversely) and both of them reach extremum at x = 0.15. The low remanence and coercivity values confirmed the formation of the superparamagnetic ferrites nanoparticles. The saturation magnetization of the samples gradually grows with Mg substitution and reach extremum at x = 0.15. Variation of saturation magnetization with Mg content can be mainly attributed to change of cation distribution, and Yafet-Kittel angle occurred between magnetic moments on B-site in the samples. The values of Young's modulus, Debye temperature, bulk modulus, rigidity modulus of the samples were determined by the values of elastic constant and wave velocities obtained from the force constants. The improvement of the elastic properties of sample x = 0.05 could be explained regarding the smaller values of the lattice parameter (a), the bond length and angle and the smaller crystallite size. © 2018 Elsevier Ltd and Techna Group S.r.l.
AUTHOR KEYWORDS: Citrate-nitrate method; Mg-Cu-Zn ferrite; Mn-Cu-Zn ferrite; Spinel ferrite; Structural, magnetic and elastic properties
INDEX KEYWORDS: Bond length; Copper alloys; Crystallite size; Elastic moduli; Elasticity; Electron emission; Ferrite; Ferrites; Field emission microscopes; Fourier transform infrared spectroscopy; High resolution transmission electron microscopy; Lattice constants; Magnesium; Magnesium alloys; Magnetic moments; Manganese alloys; Nanomagnetics; Nanoparticles; Nitrates; Rietveld refinement; Scanning electron microscopy; Structural properties; Temperature; Ternary alloys; Transmission electron microscopy; X ray diffraction; Zinc alloys, Cation distributions; Citrate-nitrate method; Cubic spinel structure; Elastic properties; Field emission scanning electron microscopy; Mg-Cu-Zn ferrites; Spinel ferrites; Vibrating sample magnetometer, Saturation magnetization
PUBLISHER: Elsevier Ltd
DOI: 10.1007/s10854-018-0069-y
Graphene oxide (GO) and reduced graphene oxide (RGO) nanostructures were synthesized using a novel method of CO gas flow under ambient pressure and at several temperatures. The produced samples of GO and RGO were structurally, chemically and optically characterized and the results were analyzed using the techniques of UV–Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, field-effect scanning electron microscopy (FE-SEM), and sheet resistance measurements. Thermo-gravimetric analysis, and FTIR indicated the successful preparation of GO and RGO. FE-SEM was used to demonstrate the layer structure of GO and RGO nanostructures. The band gap energy (Eg) of the samples was estimated through the optical absorption spectra of GO and RGOs recorded between 200 and 1100 nm wavelengths using UV–Vis spectroscopy. The results are in good agreement with the data determined by other workers. Sheet resistance of RGO shows a decreasing trend versus annealing reduced temperature. This behavior is in accordance with variation of c-axis parameter with temperature which can be suggested to be due to the removal of water molecules and oxygen-containing functional groups between the carbon layers of the GO. Removing of the latter components may results in decreasing the distance between the graphene nano-layers. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
INDEX KEYWORDS: Energy gap; Flow of gases; Graphene; Gravimetric analysis; Light absorption; Molecules; Nanosheets; Scanning electron microscopy; Sheet resistance; Thermogravimetric analysis, Ambient atmosphere; Ambient pressures; Efficient synthesis; Layer structures; Oxygen-containing functional groups; Reduced graphene oxides; Reduced graphene oxides (RGO); Sheet resistance measurements, Fourier transform infrared spectroscopy
PUBLISHER: Springer New York LLC
DOI: 10.1016/j.jmmm.2018.02.017
In this work, Y3−xSrxZrxFe5O12 (0.0 ≤ x ≤ 0.7) were synthesized by citrate precursor method at 1050 °C. The structural and magnetic properties of Y3−xSrxFe5−xZrxO12 were studied by using the X-ray diffraction technique, scanning electron microscopy, transmission electron microscopy, the Fourier transform infrared spectroscopy and vibrating sample magnetometer. XRD analysis using X'Pert package show a pure garnet phase with cubic structure (space group Ia-3d) and the impurity phase SrZrO3 is observed when the range of x value is exceeded from 0.6. Rietveld refinement using Fullprof program shows the lattice volume expansion with increasing the degree of Sr/Zr substitution. The crystallite sizes remain constant in the range of x = 0.0 − 0.5 and then increase. The different morphology observed in SEM micrographs of the samples can be related to different values of the microstrain in the samples. The hysteresis loops of the samples reveal a superparamagnetic behaviour. Also, the drop in coercivity with increasing of the substitution is mainly originated from a reduction in the magneto-elastic anisotropy energy. The values of the saturation magnetization (MS) indicate a non-monotonically variant with increasing the Sr/Zr substitution and reach a maximum 26.14 emu/g for the sample x = 0.1 and a minimum 17.64 emu/g for x = 0.0 and x = 0.2. The variation of MS, in these samples results from a superposition of three factors; reduction of Fe3+ in a-site, change in angle FeT-O-FeO, and magnetic core size. © 2018 Elsevier B.V.
AUTHOR KEYWORDS: Citrate–nitrate method; Sr/Zr substitution; Structural and magnetic properties; Yttrium iron garnet
INDEX KEYWORDS: Critical path analysis; Electron microscopy; Fourier transform infrared spectroscopy; Garnets; High resolution transmission electron microscopy; Iron oxides; Magnetic materials; Magnetic properties; Magnetism; Rietveld refinement; Saturation magnetization; Scanning electron microscopy; Strontium compounds; Transmission electron microscopy; X ray diffraction; Yttrium compounds; Zirconium compounds, Citrate precursor; Lattice volume expansion; Scanning electrons; Structural and magnetic properties; Superparamagnetics; Vibrating sample magnetometer; X-ray diffraction techniques; Yttrium iron garnets, Nanomagnetics
PUBLISHER: Elsevier B.V.
DOI: 10.1016/j.jmmm.2017.12.109
In the present work, the influence of different sintering atmospheres and temperatures on physical properties of the Cu0.5Zn0.5Fe2O4 nanoparticles including the redistribution of Zn2+ and Fe3+ ions, the oxidation of Fe atoms in the lattice, crystallite sizes, IR bands, saturation magnetization and magnetic core sizes have been investigated. The fitting of XRD patterns by using Fullprof program and also FT-IR measurement show the formation of a cubic structure with no presence of impurity phase for all the samples. The unit cell parameter of the samples sintered at the air- and inert-ambient atmospheres trend to decrease with sintering temperature, but for the samples sintered under carbon monoxide-ambient atmosphere increase. The magnetization curves versus the applied magnetic field, indicate different behaviour for the samples sintered at 700 °C with the respect to the samples sintered at 300 °C. Also, the saturation magnetization increases with the sintering temperature and reach a maximum 61.68 emu/g in the sample sintered under reducing atmosphere at 600 °C. The magnetic particle size distributions of samples have been calculated by fitting the M–H curves with the size distributed Langevin function. The results obtained from the XRD and FTIR measurements suggest that the magnetic core size has the dominant effect in variation of the saturation magnetization of the samples. © 2018 Elsevier B.V.
AUTHOR KEYWORDS: Citrate procedure method; Cu-Zn ferrite nanoparticles; Magnetic core size; Structural and magnetic properties
INDEX KEYWORDS: Binary alloys; Carbon; Carbon monoxide; Copper alloys; Copper compounds; Curve fitting; Infrared imaging; Iron compounds; Magnetic cores; Magnetism; Magnetization; Nanomagnetics; Nanoparticles; Particle size; Physical properties; Saturation magnetization; Sintering; Zinc; Zinc alloys; Zinc compounds, Applied magnetic fields; Citrate procedure method; Ferrite nanoparticles; Magnetic enhancement; Magnetization curves; Sintering atmospheres; Sintering temperatures; Structural and magnetic properties, Atmospheric temperature
PUBLISHER: Elsevier B.V.
DOI: 10.1016/j.jmrt.2017.12.006
In this study, LaFe1-yCoyO3 and La1-xSrxFe0.5Co0.5O3 nano-particles with y =0.00, 0.25, 0.50, 0.75, and 1.00 and x =0.00, 0.15, 0.30, 0.45, and 0.60 were prepared using the citrate method. The samples were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and tunneling electron microscopy. Detailed structural analysis of the samples was conducted through refining via the Rietveld method and using the Fullprof program. The structural analysis of LaFe1-yCoyO3 revealed that orthorhombic-toward-rhombohedral phase transition with Co doping and rhombohedral-to-cubic phase transformation took place in La1-xSrxFe0.5Co0.5O3 due to an increase in the Sr content. The electrical conductivity and catalytic activity of La1-xSrxFe1-yCoyO3 were also investigated. The results of the structural analysis of LaFe1-yCoyO3 pointed out to the presence of Co2+, Co3+, Fe3+ and Fe4+ ions that would contribute to the overall oxidation activity of these samples. In addition, substituting the lower ionic radius transition metal would decrease the temperature of the complete CO conversion. The increase in the catalytic activity of the sample y =0.50 in series of LaFe1-yCoyO3 could be mainly attributed to (i) the presence of Fe3+ OFe4+ and Co2+ OCo3+ couples, (ii) a rhombohedral structure with higher symmetry, and also (iii) the lower value of activation energy and higher value of σ Ox/σ Red. However, substituting Sr for La could increase the temperature of the CO conversion. LaFe0.5Co0.5O3 exhibited 95% CO conversion at 536K. © 2018 Brazilian Metallurgical, Materials and Mining Association.
AUTHOR KEYWORDS: CO oxidation; Electrical conductivity; Ferrite-cobaltite; Nano-particles; Structural phase transition; X-ray diffraction analysis
INDEX KEYWORDS: Activation energy; Binary alloys; Catalyst activity; Electric conductivity; Ferrite; Infrared spectroscopy; Lanthanum; Nanoparticles; Rietveld analysis; Scanning electron microscopy; Strontium; Structural analysis; X ray diffraction analysis; X ray powder diffraction, Catalytic properties; Co oxidation; Electrical conductivity; Lanthanum ferrites; Oxidation activities; Rhombohedral structures; Structural phase transition; Tunneling electron microscopy, Cobalt
PUBLISHER: Elsevier Editora Ltda
DOI: 10.1111/jace.14896
Magnetite exhibits unique structural, electronic, and magnetic properties in extreme conditions that are of great research interest. In this work, the effects of preparation technique on X-ray peak broadening, magnetic and elastic moduli properties of Fe3O4 nanoparticles prepared by coprecipitation (FcP-NPs) and citrate (FC-NPs) methods have been investigated. The structural characterization of the samples is evidence for a cubic structure with Fd-3m space group. The Williamson-Hall analysis was used to study crystallite sizes and lattice strain of the samples and also stress and energy density. In addition, the crystallite sizes are compared with the particle sizes and the magnetic core sizes obtained from TEM and VSM methods, respectively. In addition, the cation distribution obtained from calculated inversion parameter indicate that in the smaller particles, more amount of Fe2+ on the tetrahedral sites can be related to higher stress induced in the FcP-NPs compared to the FC-NPs. The saturation magnetization of the FcP-NPs is almost two times bigger than the saturation magnetization of the FC-NPs. It could be attributed to the decrease in the negative interaction on the octahedral site and also the magnetic moment on the tetrahedral site of the FcP-NPs. The increase in force constants of the FC-NPs determined by infrared spectra analysis compared to FcP-NPs suggests the strengthening of their interatomic bonding. The values of shear and longitudinal wave velocities obtained from force constants have been used to determine the values of Young's modulus, rigidity modulus, bulk modulus, and Debye temperature. By comparison of the elastic results of FC-NPs with the FcP-NPs, we can observe that the elastic properties of the F-NPs have been improved by synthesis method, while Poisson's ratio almost remains constant. 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 [hkl] have been calculated for the samples. © 2017 The American Ceramic Society
AUTHOR KEYWORDS: ferrites; fourier transform infrared spectroscopy; magnetic materials/properties; mechanical properties; x-ray method
INDEX KEYWORDS: Coprecipitation; Elastic moduli; Ferrite; Fourier transform infrared spectroscopy; Magnetic materials; Magnetic moments; Magnetism; Magnetization; Mechanical properties; Nanomagnetics; Nanoparticles; Poisson ratio; Rubidium compounds; Shear flow; Single crystals, Elastic stiffness constant; Infrared spectra analysis; Longitudinal wave velocity; Preparation technique; Structural characterization; Williamson-hall analysis; X ray methods; X ray peak broadening, Saturation magnetization
PUBLISHER: Blackwell Publishing Inc.
DOI: 10.1111/ijac.12650
In this work, structural and catalytic properties of La0.7Bi0.3Mn1−xCoxO3 nanocatalysts with x=0.00, 0.25, 0.50, 0.75, and 1.00 prepared by citrate method are investigated. The structural characterization using X'Pert package and Fullprof program is an evidence for structural phase transition. The values of refined unit cell volume obtained from the Rietveld analysis show decreasing and increasing tendencies for values of x≤0.5 and x>0.5, respectively. The catalytic performance tests of the catalysts show that the samples x=0.00 and 0.25 have lower temperature of CO oxidation and C2H6 combustion, respectively. © 2017 The American Ceramic Society.
AUTHOR KEYWORDS: C2H6 combustion and CO oxidation; manganite-cobaltite; nanoperovskites; structural phase transition; X-ray diffraction analysis
INDEX KEYWORDS: Combustion; Manganese; Oxidation; Rietveld analysis; X ray diffraction analysis, Catalytic performance; Catalytic properties; Co oxidation; Lower temperatures; Nanoperovskites; Structural characterization; Structural phase transition; Unit-cell volume, Catalytic oxidation
PUBLISHER: Blackwell Publishing Ltd
DOI: 10.1111/jace.14602
In this work, structural and catalytic properties of LaCo1− yMgyO3 and La1− xCaxCo0.50Mg0.50O3 nanocatalysts with x=0.00, 0.15, 0.30, 0.45, 0.60, 0.75 and y=0.00, 0.25, 0.50 prepared by citrate method are investigated. The structural characterization using X'Pert package and Fullprof program is an evidence for structural phase transition. The structural results suggest the presence of Co4+ and Co3+ ions that help to overall oxidation activity of these samples and this feature is higher for x=0.60. When substituting Mg and Ca in LaCoO3 the catalytic activity of CO oxidation shifts to lower temperature. La0.5Ca0.50Co0.5Mg0.5O3 nanocatalyst exhibits excellent CO conversion rate of 95% at 267°C. These results suggest that the lower temperature conversion of the sample x=0.60 in series of La1− xCaxCo1− yMgyO3 can be mainly attributed to the presence of (i) higher Co3+–O–Co4+ couples, (ii) a structure having the higher tolerance factor, and (iii) a lower crystallite size. © 2016 The American Ceramic Society
AUTHOR KEYWORDS: CO oxidation; cobaltite; nano-Perovskites; structural phase transition; X-ray diffraction analysis
INDEX KEYWORDS: Calcium; Catalyst activity; Crystallite size; Oxidation; Perovskite; X ray diffraction analysis, Catalytic properties; Co oxidation; Cobaltite; Lower temperatures; Nano perovskites; Oxidation activities; Structural characterization; Structural phase transition, Catalytic oxidation
PUBLISHER: Blackwell Publishing Inc.
DOI: 10.1016/j.jmmm.2016.09.029
In this work, effects of sintering atmosphere and temperature on structural and magnetic properties of Ni0.3Cu0.2Zn0.5Fe2O4 nanoparticles prepared by citrate precursor method have been studied. The structural characterization of the samples by X-ray powder diffraction and FT-IR spectroscopy is evidence for formation of a cubic structure with no presence of impurity phase. Calculated values of crystallite size and unit cell parameter show an increase with sintering temperature under different atmospheres. Variation of saturation magnetization with sintering temperature and atmosphere can be attributed to change of three factors: magnetic core size, inversion parameter and the change of Fe3+-ion concentration due to the presence of Fe4+ and Fe2+ ions. The saturation magnetization gradually grows with sintering temperature due to increase of magnetic core size and a maximum 63 emu/g was achieved at 600 °C under carbon monoxide-ambient atmosphere. © 2016 Elsevier B.V.
AUTHOR KEYWORDS: Nanoparticles; Ni-Cu-Zn ferrite; Soft ferrite; Structural and magnetic properties
INDEX KEYWORDS: Carbon; Carbon monoxide; Crystallite size; Ferrite; Ferrites; Magnetic cores; Magnetic properties; Magnetism; Magnetization; Nanomagnetics; Nanoparticles; Nickel; Saturation magnetization; Sintering; X ray powder diffraction; Zinc, Inversion parameters; Magnetic enhancement; Sintering atmospheres; Sintering temperatures; Soft ferrite; Structural and magnetic properties; Structural characterization; Unit cell parameters, Atmospheric temperature
PUBLISHER: Elsevier B.V.
DOI: 10.1016/j.ceramint.2016.04.134
In this work, structural and catalytic properties of La1−xCaxMn0.5Co0.5O3 and La1−xSrxMn0.5Co0.5O3 nano-catalysts in the concentration range of 0.00≤x≤1.00 are investigated. The structural characterization of the compounds obtained by X-ray powder diffraction and using X′Pert package and Fullprof program is an evidence for structural phase transition of the samples that can be described by variation of tolerance factor. The obtained results also have been confirmed by FTIR measurements. The structural results, and the non-uniformly changes of activation energy, band gap energy and electrical conductivity values suggest the presence of different concentration of various cations Co+2, Co+3, Co+4, Mn+4 and Mn+3 in the compounds studied. The decrease of the crystallite size with increasing Ca and Sr substitution for x up to 0.5 in La1−x(Sr, Ca)xMn0.5Co0.5O3 can be related to the increase and decrease of micro-strain, respectively. Substituting Sr having higher ionic radius with respect to La in LaMn0.5Co0.5O3 shifts the catalytic activity of CO oxidation to lower temperature, whereas, for Ca substitution the catalytic activity shifts to higher temperature. The trend of catalytic activity observed for Ca- and Sr-substituted samples can be related to different morphology observed in SEM micrographs due to different types of micro-strain. La0.5Sr0.5Mn0.5Co0.5O3 nano-catalyst exhibits excellent CO conversion rate of 95% at 175 °C. © 2016 Elsevier Ltd and Techna Group S.r.l.
AUTHOR KEYWORDS: CO oxidation; Manganite–cobaltite; Nano-catalysts; Structural phase transition
INDEX KEYWORDS: Activation energy; Calcium; Catalyst activity; Catalysts; Catalytic oxidation; Cobalt compounds; Crystallite size; Energy gap; Lanthanum; Manganites; Oxidation; Temperature; X ray powder diffraction, Catalytic properties; Co oxidation; Concentration ranges; Electrical conductivity; Low-temperature CO oxidation; Nano-catalyst; Structural characterization; Structural phase transition, Manganese
PUBLISHER: Elsevier Ltd
DOI: 10.1016/j.ceramint.2015.12.101
Structural, magnetic and catalytic properties of La0.7Sr0.3Mn1-xCoxO3 (x=0.00, 0.25, 0.50, 0.75, 1.00) nano-perovskites prepared by the citrate method are investigated. The structural characterization of the compounds by X-ray powder diffraction and using X'Pert package and Fullprof program is an evidence for a monoclinic structure (P21/n space group) with x=0.50 and a rhombohedral structure (R-3c space group) for other samples. These results have been confirmed by the FT-IR measurements. Crystallite size of the powders obtained from Halder-Wagner method has been compared with the Scherrer method. The structural and magnetic results suggest the presence of different concentrations of various cations of Co+2, Co+3, Co+4, Mn+4 and Mn+3 in the samples. Activation energy, band gap energy, and electrical conductivity measurements have been employed to explain catalytic performance of the samples. The results of performance tests show that the sample with x=0.25 has the highest catalytic activity for CO oxidation, whereas, the sample with x=0.75 has the highest catalytic activity for C2H6 combustion. © 2016 Elsevier Ltd and Techna Group S.r.l.
AUTHOR KEYWORDS: C2H6 combustion; CO oxidation; Magnetic phase transition; Manganite-cobaltite; Nano-perovskite
INDEX KEYWORDS: Activation energy; C (programming language); Catalytic oxidation; Combustion; Crystallite size; Energy gap; Infrared imaging; Magnetism; Manganese; Oxidation; Perovskite; X ray powder diffraction, Catalytic performance; Co oxidation; Electrical conductivity measurements; Magnetic phase transitions; Monoclinic structures; Nano perovskites; Rhombohedral structures; Structural characterization, Catalyst activity
PUBLISHER: Elsevier Ltd
In this work, structural, magnetic and catalytic properties of LaMn1-xCoxO3 (x = 0.00, 0.25, 0.50, 0.75, 1.00) are investigated. The structural characterization of the samples by X-ray powder diffraction and using the X'Pert package and Fullprof program is evidence for a monoclinic structure (P21/n space group) with x = 0.5 and a rhombohedral structure (R-3c space group) for other samples. These results have been confirmed by FTIR measurements. The magnetic characterizations of the samples have been studied by magnetization measurement versus temperature and field. The structural and magnetic results show the ferromagnetic interactions of Co2+-Mn4+ for x ≤ 0.5 are being progressively replaced by the less effective Co2+-Co3+ and Mn4+-Co3+ interactions for x > 0.5. The catalytic activity of LaMn1-xCoxO3 was evaluated for C2H6 combustion and CO oxidation reactions. Under similar reaction conditions, the catalytic results show that the LaMn0.5Co0.5O3 nano-perovskite is the best catalyst for C2H6 combustion and CO oxidation. © 2016 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.
AUTHOR KEYWORDS: C2H6 combustion; CO oxidation; Manganite-cobaltite; Nano-perovskite; Structural and magnetic phase transition
PUBLISHER: Bulgarian Academy of Sciences
DOI: 10.1016/j.ica.2016.07.028
In the present work, a series of new Schiff base ligands from acetylacetone and salicylaldehyde with sulfonamides derivatives were synthesized and characterized by spectral and analytical techniques. The molecular structures of ligands, N-({4-[(E)-(2-hydroxybenzylidene)amino]phenyl}sulfonyle)acetamide (HL1), N-({4-[(E)-(2-hydroxybenxiliden)amino]phenyl}sulfonyle)benzamide (HL2) and 4-((4-oxopentan-2ylidene)amino)benzenesulfonamide (HL3) were also determined by the method of X-ray diffraction. Also, new copper(II) complexes [CuLx](x = 1 for 1, x = 2 for 2, x = 3 for 3) constructed from HLxwere synthesized and characterized by FT-IR, UV–vis spectroscopy and XRD. The copper(II) complexes were screened for their antimicrobial activities against the selected bacteria and compared to the free ligands, using the disc diffusion method. © 2016 Elsevier B.V.
AUTHOR KEYWORDS: Antibacterial activity; Crystal structures; Rietveld analysis; Schiff base; Sulfonamides
PUBLISHER: Elsevier S.A.
DOI: 10.1016/j.jmmm.2015.06.016
Bi1-y-xBayErxFeO3 [BByExFO, (0.13y0.17, 00.2)] nanoparticles were successfully synthesized by a sol-gel method. The structural, microstructural and magnetic properties have been investigated, using X-ray diffraction, Raman scattering, field emission scanning electron microscopy (FE-SEM) and magnetometry measurements at room temperature. The refinement of X-ray diffraction pattern of BB0.15E0FO indicates a phase transition from rhombohedral (R3c) to tetragonal (P4mm) with increasing Ba content and a transition from the coexistence of rhombohedral-tetragonal phase to orthorhombic (Pbnm) in BB0.15ExFO samples with increasing Er concentration. The Raman analysis confirms crystal phase transition in BB0.15ExFO compounds. The FE-SEM and TEM analysis show that the average nanoparticle size is about 50-100 nm and it decreases with Er concentration. The remnant magnetisation of BB0.15E0.1FO sample (Mr=0.98 emu/g) is approximately two times greater than compared to BB0.15E0FO (Mr=0.51 emu/g) that may be attributed to the collapse of spin structure and modifying exchange interactions because of Er+3 doping. This enhancement in magnetic properties at room temperature can play an important role for the practical applications. © 2015 Elsevier B.V. All rights reserved.
AUTHOR KEYWORDS: BiFeO3; Magnetic properties; Nanoparticles; Raman spectroscopy; Sol-gel preparation
INDEX KEYWORDS: Bismuth compounds; Enamels; Erbium; Ferromagnetism; Field emission microscopes; Magnetic properties; Magnetism; Nanoparticles; Raman spectroscopy; Scanning electron microscopy; Sol-gel process; Sol-gels; Synthesis (chemical); X ray diffraction, Crystal phase transition; Er concentrations; Field emission scanning electron microscopy; Magnetometry measurements; Nanoparticle sizes; Room temperature; Sol gel preparations; Tetragonal phase, Nanomagnetics
PUBLISHER: Elsevier
DOI: 10.1002/crat.201200423
Lanthanum oxide nanoparticles were synthesized via thermal decomposition method of the lanthanum nitrate in the presence of citric acid or starch as emulsifier. The effects of emulsifier and calcination temperature were investigated on the phase transformation and particle size distribution of the products. La2O3 nanoparticles were synthesized by drying lanthanum precursor and emulsifier solution, followed by calcination process at 600 and 900°C, respectively. Products were characterized by Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermal analysis (TG/DTA) and nitrogen adsorption method (porous characteristics). The morphology of the samples analyzed using scanning electron microscopy (SEM). Average crystallite size of the products was calculated by XRD data and average particle size was measured from the TEM micrographs. Lanthanum dioxycarbonate in different forms of the tetragonal and monoclinic is crystallized in the presence of citric acid and starch during the calcination at 600°C, respectively. The hexagonal structure, however, is detected as the only crystalline phase formed by calcination at 900°C. Lanthanum oxide nanoparticles are formed at lower temperature in the presence of starch in compared with citric acid when is used as emulsifier. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
AUTHOR KEYWORDS: Citric acid; Emulsifier; Lanthanum oxide; Nanoparticles; Starch
INDEX KEYWORDS: Average particle size; Calcination temperature; Emulsifier; Fourier transform infra red (FTIR) spectroscopy; Hexagonal structures; Lanthanum precursors; Porous characteristics; Thermal decomposition methods, Calcination; Citric acid; Decomposition; Emulsification; Gas adsorption; Lanthanum; Lanthanum alloys; Lanthanum oxides; Nanoparticles; Particle size analysis; Scanning electron microscopy; Starch; Thermoanalysis; Transmission electron microscopy; X ray diffraction, Synthesis (chemical)
DOI: 10.1016/j.catcom.2012.08.009
The effect of partial substitution of lanthanum by strontium or bismuth in LaMnO 3 nano-perovskites, i.e. La (1 - x)(Sr or Bi) xMnO 3 samples, in which x = 0.0, 0.2 or 0.4, is explored for stoichiometric oxidation of carbon monoxide with air. FT-IR and XRD analyses confirmed the perovskite structure for the catalysts. Average crystallite size of the products was calculated by the data of XRD and average particle size was measured from the TEM micrographs. Small effect is observed on perovskite phase formation of LaMnO 3 on substitution of lanthanum with strontium or bismuth. Under similar reaction conditions, small substitution of bismuth has a more positive effect than strontium on lowering the CO oxidation temperature. © 2012 Elsevier B.V.
AUTHOR KEYWORDS: Bismuth; Carbon monoxide; Lanthanum manganite; Nano-perovskite; Oxidation; Strontium
INDEX KEYWORDS: Average particle size; Carbon monoxide oxidation; Co oxidation; Lanthanum manganites; Nano perovskites; Partial substitution; Perovskite phase formation; Perovskite structures; Reaction conditions; Structural feature; XRD; XRD analysis, Bismuth; Carbon monoxide; Catalysts; Lanthanum alloys; Manganese oxide; Oxidation; Perovskite; Strontium; Transmission electron microscopy, Lanthanum
DOI: 10.1016/j.physb.2012.04.034
In this work, The magnetoelastic properties of polycrystalline samples of Tb 3 (Fe 28-xCo x) V 1.0 (x=0, 3, 6) intermetallic compounds are investigated by means of linear thermal expansion and magnetostriction measurements in the temperature range of 77-515 K under applied magnetic fields up to 1.5 T. The linear thermal expansion increases with the Co content. The well-defined anomalies observed in the linear thermal expansion coefficients for Tb 3 (Fe 28-xCo x) V 1.0 (x=0, 3, 6) compounds are associated with the magnetic ordering temperature for x=0 and spin reorientation temperatures for x=3, 6. Below transition temperatures, the value of the longitudinal magnetostriction (λ Pa) at 1.6 T increases with Co content. © 2012 Elsevier B.V. All rights reserved.
AUTHOR KEYWORDS: 3:29 Intermetallic compounds; Magnetocrystalline anisotropy; Magnetostriction; Thermal expansion
INDEX KEYWORDS: Applied magnetic fields; Co content; Linear thermal expansion coefficients; Linear thermal expansions; Magnetic ordering temperatures; Magnetoelastic properties; Magnetostriction measurements; Polycrystalline samples; Spin reorientation temperature; Temperature range, Magnetic fields; Magnetocrystalline anisotropy; Magnetostriction; Magnetostrictive devices; Neel temperature; Thermal expansion, Cobalt compounds
DOI: 10.1016/j.mssp.2010.10.004
Co-doped SnO2 TCOs were prepared by spray pyrolysis technique and the influence of N2- and Ar-ambient annealing on their structural, electrical and optical properties was studied. XRD results show that all samples become single phase after post-annealing treatments. In addition, the Co-doped films exhibit a faceting characteristic that is conserved after the post-annealing treatments. Analysis of the XRD patterns shows that the size of crystallite decreases with increasing microstrain and both of them reach extremum at about 20 at% doping level. Electrical measurements demonstrate gradual increase in resistivity with increasing doping level. The annealing causes increase in the electrical resistivity of the cobalt-doped samples. About 40% of this increase should be due to penetration of nitrogen ions within the rutile structure and the remaining 60% may be attributed to the structural and compositional relaxations. The optical spectra show that transparency of the samples in the visible region decreases between 10% and 40% with increasing cobalt content. Although transparency of the samples at lower than 30 at% doping level slightly increases after post-annealing treatments, this increase is compensated for by compositional relaxations in the samples with more cobalt content. The band gap energies are increased by about 1.5% by post annealing treatment. © 2010 Elsevier Ltd. All rights reserved.
AUTHOR KEYWORDS: Dilute magnetic semiconductors; Spray pyrolysis; Transparent conducting oxide
INDEX KEYWORDS: Band gap energy; Co-doped; Co-doped SnO; Cobalt content; Dilute magnetic semiconductors; Doped sample; Doping levels; Electrical and optical properties; Electrical measurement; Electrical resistivity; Micro-strain; Nitrogen ions; Optical spectra; Post annealing treatment; Rutile structure; Single phase; Spray-pyrolysis techniques; Transparent conducting films; Transparent conducting oxide; Visible region; XRD; XRD patterns, Annealing; Cobalt; Conductive films; Crystallite size; Electric conductivity; Magnetic semiconductors; Oxide minerals; Semiconducting antimony; Semiconductor doping; Transparency, Spray pyrolysis
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