Iron oxide (Fe3O4) nanoparticles were synthesized by a facile microwave combustion method. X-ray diffraction and energy dispersive X-ray spectroscopy results showed that the as-prepared product was pure Fe3O4 without any impurity. The mechanism for the formation of Fe3O4 by microwave combustion method is also discussed. Microwave combustion produced sufficient energy for the formation of Fe3O4, because of its homogeneous distribution within the raw materials. This results in the formation of nanoparticles, early phase formation and different morphologies within few minutes. Magnetic analysis revealed that the Fe3O4 nanoparticles had ferromagnetic behavior at room temperature with saturation magnetization of 66.12 emu/g. © 2013 The Korean Society of Industrial and Engineering Chemistry.

John Kennedy L

Physics

School of Advanced Sciences

Chennai Campus

Manikandan A

Vijaya J.J

Mary J.A

Dinesh A.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Journal of Industrial and Engineering Chemistry

International Journal of Environmental Health Research

Comparative ecotoxicity assessment of magnetosomes and magnetite nanoparticles

Zn1−xNixO with 0 ≤ x ≤ 0.2 nanoparticles (NPs) were prepared by co-precipitation with subsequent annealing at 500 °C for 2 h. For a better control of particle's growth, a non-ionic surfactant namely Tween-80 was used during the preparation process. XRD Rietveld analysis confirmed the formation of the hexagonal wurtzite-type structure along with a secondary phase namely NiO. SEM observations revealed remarkable change in morphology, including rods, sheets and spheres. The purity of the as-prepared NPs as checked by EDAX analysis indicated that the chemical composition of Zn, Ni and O was in good agreement with the starting stoichiometries. The defect states were revealed from the UV and visible emissions of the photoluminescence spectra. The DRS analysis showed blue shift as Ni2+increases from 5 to 20%. The existence of a peak at 432 cm−1in FTIR spectra confirmed the formation of ZnO phase. The Magnetization-Field (M-H) curves revealed the existence of ferromagnetism in Ni-doped ZnO NPs, which was attributed to bound magnetic polaron (BMP) mechanism. © 2016 Elsevier B.V.

Journal of Alloys and Compounds

Optical and magnetic properties of Ni-doped ZnO nanoparticles

Recent developments show that the exceptional physical, optical, magnetic, and electrical properties of spinel ferrite (SF) nanomaterials have now attracted the attention as high-density data storage materials, catalysts, gas sensors, rechargeable lithium batteries, information storage systems, magnetic bulk cores, adsorbents, magnetic fluids, microwave absorbers, and medical diagnostics. The aim of this review consists on an overview on the methods of preparation, the crystal structure and application of SFs used in technology for the design of new materials and devices. The chapter begins with a review of the different synthesis methods commonly used for the preparation of SFs. Then, the structural features of spinel unit cell, crystal chemical parameters, and extrinsic magnetic and optical properties are described in this chapter. Since the magnetism of SFs depends not only on particle chemistry and phase but also on the particle size and environment, the role of cationic distribution and ion exchange interaction are explored in determining the magnetic properties of the system. In addition, the potential applications of SFs in different fields of technology are also discussed. © Springer International Publishing AG 2017.

Springer Proceedings in Physics Nanophysics, Nanomaterials, Interface Studies, and Applications

Spinel Ferrite Nanoparticles: Synthesis, Crystal Structure, Properties, and Perspective Applications

Zn1-xCuxO (0 ≤ x ≤ 0.2) nanoparticles were prepared by co-precipitation method followed by drying at 200 °C. A non-ionic surfactant Tween-80 which was not reported in earlier studies, was used during preparation process. X-ray diffraction analysis showed the formation of wurtzite ZnO phase nanostructures. The Rietveld analysis showed the appearance of impurity phase (CuO), when Cu2+ was doped with ZnO (x = 0.05 to 0.2). Morphological observations using scanning electron microscopy show the formation of nanoparticles with remarkable morphologies. Photoluminescence spectra revealed emission bands in both UV and visible regions due to the defect centres acting as trap levels. Diffuse reflectance spectroscopy (DRS) showed a decreasing trend in the value of the band gap with increasing Cu2+ doping for lower concentration (x = 0 to 0.1) and then increasing trend for higher concentration of Cu2+ doping. (x = 0.1 to 0.2). The elemental composition of Zn, Cu and O was quantitatively obtained from EDAX analysis where the chemical composition was close to the starting stoichiometries. Magnetisation-Field (M-H) hysteresis curves revealed the appearance of ferromagnetic behaviour, where the magnetic characteristics such as coercivity and saturation magnetization values, were found to be sensitive to Cu2+ doping level. © Copyright 2016 American Scientific Publishers.

Journal of Nanoscience and Nanotechnology

Structural, Optical and Magnetic Properties of Cu-Doped ZnO Nanoparticles by Co-Precipitation Method

Pure and Mn2+ doped ZnO nanoparticles (Zn1-xMnxO with 0 ≤ x ≤ 0.2) were prepared by co-precipitation method followed by drying at 200°C. A non-ionic surfactant, Tween-80, was used during preparation process to control the particles growth. X-ray diffraction analysis revealed the formation of hexagonal wurtzite for pure and Mn2+ doped ZnO samples with a minor secondary phase. The Rietveld analysis confirmed the formation of hexagonal wurtzite structure as well as the secondary phase as Mn3O4 for all doping levels. Morphological observations showed the formation of nanoparticles with remarkable morphologies of which spherical nanostructures seem to be more dominant. The quantitative analysis from EDAX confirmed the purity of the as-prepared nanopowders and that the chemical composition of Zn, Mn and O seem to be close to the starting stoichiometries. Emission bands in both UV and visible regions were revealed by photoluminescence spectra, which were due to defect centers acting as trap levels. The diffuse reflectance spectroscopy (DRS) indicated a decrease in the value of bandgap with increasing Mn doping concentration. The ferromagnetic behaviour was very clear from the Magnetisation-Field (M-H) hysteresis curves, where the magnetic characteristics such as coercivity and saturation magnetization values, were found to be sensitive to Mn doping level. © 2016 Elsevier B.V. All rights reserved.

Journal of Molecular Structure

Structural, microstructural, optical and magnetic properties of Mn-doped ZnO nanostructures

Nano-sized copper doped zinc ferrite powders, Zn1-xCu xFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized by microwave combustion method. The structural, morphological and magnetic properties of the products were determined and characterized in detail by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). X-ray analysis showed that all compositions crystallize with a cubic spinel-type structure. The lattice parameter decreased from 8.443 to 8.413 Å with increasing Cu content. The average crystallite size was found in the range of 41.20-45.84 nm. Magnetic measurements revealed that for lower Cu concentration (x ≤ 0.2), the system shows a superparamagnetic behavior whereas for higher concentration (x ≥ 0.2), it becomes ferromagnetic. It has been explained in terms of random distribution of Zn2+ and Fe 3+ ions at tetrahedral [A] and octahedral [B] sites. The saturation magnetization (Ms) varies considerably with Cu content to reach a maximum value for Cu0.5Zn0.5Fe2O4 composition, i.e. 58.58 emu/g. The high saturation magnetization of these samples suggests that this method is suitable for preparing high quality nanoparticles for magnetic applications. The broadband visible emission is observed in the entire photoluminescence (PL) spectrum and the estimated energy band gap is about 2.1 eV. The composition with x = 0.5 showed the highest intensity and was explained on the basis of disordered cluster model. © 2012 Elsevier B.V. All rights reserved.

Structural, optical and magnetic properties of Zn1−xCuxFe2O4 nanoparticles prepared by microwave combustion method

Nickel oxide (NiO) nano- and microstructures were synthesized by the microwave combustion method (MCM) and the conventional combustion method (CCM) using urea as the fuel. The as-synthesized NiO powders were characterized by X-ray powder diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, Brunauer-Emmett-Teller (BET) analysis and vibrating sample magnetometer (VSM) analysis. The XRD results confirmed the formation of cubic phase NiO. The formation of NiO nano- and microstructures were confirmed by HR-SEM and HR-TEM and their possible formation mechanisms were also proposed. The optical absorption and photoluminescence emissions were determined by DRS and PL spectra respectively. The band gap was measured using the Kubelka-Munk model and it shows 3.36 eV for NiO (MCM) and 2.70 eV for NiO (CCM). The magnetic properties of the synthesized NiO nano- and microstructures were investigated with a vibrating sample magnetometer (VSM) and their hysteresis loops were obtained at room temperature. The relatively high saturation magnetization (21.22 emu/g) of NiO-MCM shows that it is ferromagnetic and low saturation magnetization (7.43 emu/g) of NiO-CCM confirms the superparamagnetic behavior. © 2013 Elsevier B.V.

Physica E: Low-dimensional Systems and Nanostructures

Comparative investigation of NiO nano- and microstructures for structural, optical and magnetic properties

Pure and strontium doped zinc ferrite (Zn1-xSr xFe2O4) nanoparticles were prepared by the microwave combustion method using urea as the fuel. Rietveld refinements of X-ray diffraction pattern confirm the formation of single cubic spinel phase with an average crystallite size in the range of 25-42 nm. The broad visible emission band is observed in the entire photoluminescence spectrum. The estimated band gap energy is found to decrease with increasing Sr content, i.e. 2.1-1.72 eV. Magnetic measurements at room temperature revealed that at lower Sr concentration (x≤0.2), the system shows a superparamagnetic behavior, whereas at higher Sr concentration (x≥0.2), it becomes ferromagnetic. The relatively high saturation magnetization of the as-prepared Sr-doped ZnFe 2O4 nanoparticles suggest that this method is suitable for preparing high-quality nanocrystalline magnetic ferrites for practical applications. The mechanism for the formation of ZnFe2O4 by the microwave combustion method is also discussed in the present study. Microwave combustion produced sufficient energy for the formation of ZnFe 2O4, because of its homogeneous distribution within the raw materials. This results in the formation of nanoparticles and early phase formation within few minutes of time. © 2013 Elsevier Ltd and Techna Group S.r.l.

Journal	Data powered by TypesetJournal of Industrial and Engineering Chemistry
Publisher	Data powered by TypesetElsevier BV
ISSN	1226-086X
Open Access	0