Geitu Yirga; H C Ananda Murthy; Eshetu Bekele
Abstract
Humic acid modified magnetite nanoparticles (HA-Fe3O4 NPs) were synthesized by co-precipitation method by varying the precursor magnetite to HA ratio of 10:1 and 20:1. The synthesized NPs were characterized by FTIR, XRD, SEM-EDX and UV-Vis DR Techniques. The appearance of C=O vibration at 1390 cm -1 ...
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Humic acid modified magnetite nanoparticles (HA-Fe3O4 NPs) were synthesized by co-precipitation method by varying the precursor magnetite to HA ratio of 10:1 and 20:1. The synthesized NPs were characterized by FTIR, XRD, SEM-EDX and UV-Vis DR Techniques. The appearance of C=O vibration at 1390 cm -1 confirms positive interaction of carboxylate anion of HA and Fe3O4. The XRD pattern and SEM image shows bare Fe3O4 and HA-Fe3O4 (10:1 and 20:1) exhibit cubic spinel structure and the spherical shape morphology, respectively. The crystallite sizes of NPs were found to be 11.50 nm, 9.17 nm and 12.65 nm for bare, 10:1 and 20:1 Fe3O4-NPs, respectively. The adsorption capacity for the dye was found to increase with increase in contact time, adsorbent dose and initial pH of the solution. The result was best fitted to pseudo 2 nd order kinetics model and Langmuir isotherm model. The methylene blue (MB) removal efficiency of bare, 10:1 and 20:1 Fe3O4-NPs from aqueous solutions was recorded to be 95.8%, 99.4%, and 97.6%, respectively. The study confirms the greater efficiency of HA-Fe3O4 NPs compared to bare Fe3O4 for the removal of MB dye. The MB removal efficiency of HA-Fe3O4 NPs was found to be proportional to amount of adsorbed HA. Copyright © VBRI Press.
Lili Zhang; Hongxiang Jiang; Jiuzhou Zhao
Abstract
The microstructure evolution in a Fe-Cu alloy with/without pre-deformation during the aging treatment is investigated numerically. The results demonstrate that although the Cu precipitates first nucleate on dislocations, the summit of the nucleation rate occurs in the matrix. Most of Cu particles situate ...
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The microstructure evolution in a Fe-Cu alloy with/without pre-deformation during the aging treatment is investigated numerically. The results demonstrate that although the Cu precipitates first nucleate on dislocations, the summit of the nucleation rate occurs in the matrix. Most of Cu particles situate in the matrix immediately after the nucleation. The preferential dissolution of Cu precipitates in the matrix occurs during the Ostwald repining stage, and the vast majority of the residual particles situate on dislocations in an overaged alloy.
Kamlesh V. Chandekar; K. Mohan Kant
Abstract
Cobalt ferrite (CoFe2O4) nanoparticles were synthesized by co-precipitation route at 80 °C. X-ray diffraction pattern (XRD) confirmed cubic inverse spinel structure of CoFe2O4 nanoparticles. The average crystallite size of CoFe2O4 nanoparticles estimated by X-ray line profile fitting was 12±2 ...
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Cobalt ferrite (CoFe2O4) nanoparticles were synthesized by co-precipitation route at 80 °C. X-ray diffraction pattern (XRD) confirmed cubic inverse spinel structure of CoFe2O4 nanoparticles. The average crystallite size of CoFe2O4 nanoparticles estimated by X-ray line profile fitting was 12±2 nm for high-intensity peak (311). The particle size, distribution and surface morphology was estimated using Transmission electron microscopy (TEM) with average particle size of 16±2 nm. Raman spectra of CoFe2O4 nanoparticles exhibits phonon modes corresponding to tetrahedral sites (679 cm -1 ) and octahedral sites (465 cm -1 ) respectively. The saturation magnetization Ms for CoFe2O4 sample is found to be 63 and 82 emu/g at 300 K and 10 K respectively. The cubic magnetic anisotropy constant K1 and saturation magnetization Ms are obtained by fitting M versus H isotherm to the saturation approach law. By fitting, K1 and Ms is 2.16 x10 5 J/m 3 and 66 emu/g respectively at 300 K. The cubic magnetic anisotropy constant K1 = 5.49 x10 5 J/m 3 is evaluated at blocking temperature of 144 K. The particle size and L-S coupling is responsible for superparamagnetic behaviour of CoFe2O4 nanoparticles. Fitting of FC curve provides Curie temperature at Tc = 823K using modified Bloch’s law for CoFe2O4 nanoparticles. Tunable particle sizes by controlling the magnetic anisotropy and L-S coupling will tailor magnetic properties and usage in bio-medical applications
S.E.Naina Vinodini
Abstract
Al3Fe5O12 (AIG) nanopowders were synthesized at different pH using aqueous co-precipitation method. The effect of pH on the phase formation of AIG is characterized using XRD, TEM, FTIR and TG/DTA. From the Scherer formula, the particle sizes of the powders were found to be 15, 21, 25 and 30 nm for pH= ...
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Al3Fe5O12 (AIG) nanopowders were synthesized at different pH using aqueous co-precipitation method. The effect of pH on the phase formation of AIG is characterized using XRD, TEM, FTIR and TG/DTA. From the Scherer formula, the particle sizes of the powders were found to be 15, 21, 25 and 30 nm for pH= 9, 10, 11 and 12, respectively. It is found that as the pH of the solution increase the particle size also increases. It is clear from the TG/DTA curves that as the pH is increasing the weight losses were found to be small. The nanopowders were sintered at 900°C/4hrs using conventional sintering method. The phase formation is completed at 800°C/4h which is correlated with TG/DTA. The average grain size of the samples is found to be ~55 nm. As the pH increases the magnetization values are also increasing. The saturation magnetization was found to be 4 emu/g, 6 emu/g, 7 emu/g and 9 emu/g corresponding to pH= 9, 10, 11 and 12, respectively which clearly shows that the magnetization values are dependent on pH. Room temperature magnetization measurements established these compounds to be soft magnetic. The dielectric and magnetic properties (εʹ, εʺ, µÊ¹ and µÊº) of AIG was studied over a wide range of frequency (1GHz-50GHz). With increase of pH both εʹ and µÊ¹ increased. This finding provides a new route for AIG materials that can be used in the gigahertz range.
Satyendra Singh; B. C. Yadav; Archana Singh; Prabhat K. Dwivedi
Abstract
In this paper we report the synthesis of iron-antimonate (FeSbO4) via co-precipitation method for the LPG sensing application. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDAX) were used to confirm the crystal structure, crystallite size, surface ...
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In this paper we report the synthesis of iron-antimonate (FeSbO4) via co-precipitation method for the LPG sensing application. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDAX) were used to confirm the crystal structure, crystallite size, surface morphology and elemental composition of the sensing material. Our XRD results confirm the single phase formation with tetragonal crystal structure of the synthesized material. Extremely broad reflections were observed indicating nanosized particle nature of the material obtained. The estimated value of average crystallite size was found 3 nm. Optical characterizations were done using UV-visible spectrophotometer and the value of energy band gap was found 3.8 eV by Tauc plot. Fine powder resulted from the chemical co-precipitation reaction was used to prepare the LPG sensing element in the form of pellet. The average sensor response of the FeSbO4 pellet was 2.2. LPG sensor based on iron-antimonate shows 97% reproducibility after one month, which illustrates the stability of the fabricated sensor. Electrical properties of iron-antimonate in air were also investigated.
V. Ramaswamy; R.M. Vimalathithan; V. Ponnusamy
Abstract
Precipitation is a hopeful process for nanoparticle production due to rapid expedient, highly economic and uncomplicated. Barium sulphate nanoparticles were prepared through precipitation process via barium chloride and sodium sulphate as the reagents in water-benzene reaction medium. Eight different ...
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Precipitation is a hopeful process for nanoparticle production due to rapid expedient, highly economic and uncomplicated. Barium sulphate nanoparticles were prepared through precipitation process via barium chloride and sodium sulphate as the reagents in water-benzene reaction medium. Eight different compositions of mixed solvents, including pure water, 20 vol. %, 30 vol. %, 50 vol. %, 70 vol. %, 80 vol. %, 90 vol. % and 95 vol. % of benzene were practiced. The effects of the volume percentage of benzene in the aqueous medium on the resultant barium sulphate nanoparticles were scrutinized. The products were characterized through X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) with Energy Dispersive X-ray Spectrum (EDX) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. The synthesized nanoparticles are well dispersed and they exhibit an orthorhombic structure and spherical in morphology with an average size of 35.9 nm. From this we establish, water-benzene mixed solvent inhibits barium sulphate nucleation growth.