Structural, morphological and magnetic properties of divalent copper-substituted Co–Zn Nanoferrites

2018 ◽  
Vol 32 (14) ◽  
pp. 1850172 ◽  
Author(s):  
B. B. V. S. Vara Prasad ◽  
K. V. Ramesh ◽  
Adiraj Srinivas
Keyword(s):  
Magnetic Properties ◽  
Magnetocrystalline Anisotropy ◽  
Copper Ions ◽  
Spinel Phase ◽  
Structural Parameters ◽  
Spherical Particles ◽  
Divalent Copper ◽  
Absorption Bands ◽  
Cobalt Ions ◽  
Morphological Studies

Nanocrystalline Co[Formula: see text]Zn[Formula: see text]Cu[Formula: see text]Fe2O4 spinel ferrites were prepared by autocombustion method with citric acid as fuel. Paramagnetic divalent copper ions substituted in place of ferromagnetic cobalt ions resulted in the modifications of structural and magnetic properties of the system. All samples were characterized with X-ray diffraction technique for structure determination. Crystallite sizes were calculated using Williamson–Hall plot and size–strain plots. Cation distribution and all other structural parameters were presented. Transmission electron microscopy measurements were done for x = 0 and x = 0.15 and they showed well-developed spherical particles with average sizes of 35 nm and 48 nm. Morphological studies were performed and grain growth was observed to be increased with copper concentration. EDAX measurements revealed the stoichiometric proportions of the samples as per the chemical composition. Mid-IR spectroscopy was used to characterize the spinel phase and displayed two characteristic absorption bands in all samples with a slight shift. M–H loops were recorded using vibrating sample magnetometer at room-temperature and highest saturation magnetization was observed to be 50.2 emu/g for the base (x = 0) sample. Magnetocrystalline anisotropy was discussed with the help of magnetocrystalline anisotropy constant K1.

scholarly journals Morphology and magnetic properties of lanthanum (La3+) substituted manganese, chromium nano ferrites

2019 ◽  
Vol 10 (2) ◽  
pp. 1102
Author(s):  
Hayder Abdulameer Abbas ◽  
Adnan Hussein Ali ◽  
Ban Mohammad Hasan
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Sol Gel ◽  
Particle Diameter ◽  
Average Crystallite Size ◽  
Spherical Particles ◽  
Average Particle ◽  
Absorption Bands ◽  
X Ray ◽  
Manganese Chromium

<span>Several studies have been carried out to investigate the effect of Lanthanum (La<sup>3+</sup>) ion substitution on the structural and magnetic properties of manganese-chromium (Mn-Cr) ferrite of chemical formula Mn La<sub>x</sub>Cr Fe<sub>2</sub>O<sub>4</sub>(x=0.0, 0.25 and 0.5). Such studies have made efforts to improve the magnetic and structural properties of manganese-chromium (Mn-Cr) ferrite by using lanthanum substituted nano ferrites and then synthesized using the sol-gel method and annealed at a temperature of 700<sup>o</sup>C. The changes that occurred in the structure of the nano ferrites as a result of lanthanum substitution were identified using X-ray diffraction (XRD). Based on Debye-Scherrer equation, the XRD data were used in measuring the particle sizes of different diffraction and average crystallite size by means of Fourier Transform infrared spectroscopy (FTIR). In analyzing the morphology of the nano ferrites, scanning electron microscopy (SEM) was used, elemental compassion was studied using energy dispersive X-ray spectroscopy (EDAX), and the average particle diameter was determined using Transmission electron microscopy (TEM) studies. FTIR spectral analysis of the prepared samples under investigations revealed the formation of a single phase spherical particles. Two important absorption bands were observed; one (<em>ν<sub>1</sub></em>) around 556 cm<sup>-1</sup>, which is attributed to the intrinsic vibrations of tetrahedral complexes, while the other low frequency band (<em>ν<sub>2</sub></em>) was around 430 cm<sup>-1</sup>, and attributed to octahedral complexes.</span>

scholarly journals Microwave Studies of Environmental Friendly Ferroelectrics

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
S. N. Mathad ◽  
Vijaya Puri
Keyword(s):  
Structural Parameters ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
Band Frequency ◽  
Lattice Constants ◽  
Texture Coefficients ◽  
Morphological Studies ◽  
Absorption Studies ◽  
Coupling Mode

The structural and microwave studies of lead-free barium niobates ceramics prepared by the high temperatures solid state reaction technique are reported. The structural parameters such as the lattice constants, average crystallite size (D), texture coefficients (TC), dislocation density, and microstrain have been determined using X-ray diffraction data. Surface morphological studies were carried out using scanning electron microscopy (SEM) technique. The strong absorption bands at ~816 cm−1, 641 cm−1, and 482 cm−1 are associated with the coupling mode between Nb–O stretching modes observed in FTIR studies. The electromagnetic transmittance, absorption, studies of barium niobates in the X band frequency range frequencies using waveguide reflectometer technique are reported.

scholarly journals Absorption spectra and crystal chemistry of quartz implanted with cobalt ions

2021 ◽  
Vol 63 (5) ◽  
pp. 57-66
Author(s):  
A. I. Bakhtin ◽  
A. V. Mukhametshin ◽  
O. N. Lopatin ◽  
V. F. Valeev ◽  
V. I. Nuzhdin ◽  
...  
Keyword(s):  
Raw Materials ◽  
Spinel Phase ◽  
Ion Beam ◽  
South Urals ◽  
High Dose ◽  
Rock Crystal ◽  
Absorption Bands ◽  
Cobalt Ions ◽  
Cobalt Spinel ◽  
Wide Range

Background. High-dose implantation of cobalt ions into the crystal structure of natural colourless quartz was carried out. Samples of crystal plates of rock crystal from the Svetlinskoye deposit in the South Urals plane-parallel were studied. All samples were crystallographically oriented perpendicular to the symmetry axis of the third order. Cobalt implantation into quartz was carried out using an ILU-3 ion-beam accelerator along the С axis of symmetry.Aim. To determine the ranges of thermal annealing for a controlled change in the sample colour and to establish the crystal-chemical features of the changes occurring in quartz matrix due to ionbeam modification of mineral properties.Materials and methods. Implantation modes included: room temperature, residual vacuum 10–5 torr, radiation dose from 1.0×1017 to 1.5×1017 ion/cm2 at a constant ion current density of 10 μA/cm2. Post-implantation heat treatment was carried out in three stages. The control of crystallochemical changes was carried out using a highly sensitive spectrophotometer with a wide range of wavelengths.Results. It was found that the revealed absorption bands are associated with electronic transitions in cobalt ions (Со2+ and Со 3+) coordinated in the crystal matrix of implanted and heat-treated rock crystal. The formation of an independent ultradispersed spinel phase in the irradiated quartz matrix was confirmed. The newly formed phase belongs to a partially reversed cobalt spinel.Conclusions. Taking into account the quantum-optical properties of cobalt spinel (laser shutters), the method of ion-beam modification of mineral crystal structures, quartz in particular, is highly promising in terms of creating new composite materials based on natural and artificial mineral raw materials.

Structural and magnetic properties of nitrided finemet-type ribbons

2000 ◽  
Vol 77 (9) ◽  
pp. 731-736
Author(s):  
H Atmani ◽  
S Grognet ◽  
J Teillet ◽  
K Zellama ◽  
R Zuberek
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Crystalline Phase ◽  
Room Temperature ◽  
Structural Parameters ◽  
Thermochemical Treatment ◽  
Specific Magnetization ◽  
Nano Structure ◽  
Magnetostriction Constant ◽  
Structural And Magnetic Properties

Nitriding thermochemical treatment under suitable parameters is used to nano-crystallize Fe73.5Cu1Nb3Si13.5B9 ribbon. This new kind of treatment leads to finer nano-structure and modifies the structural parameters of the α-Fe(Si) phase, obtained during the treatment. The magnetic properties are also improved; specific magnetization at room temperature and Curie temperature of the crystalline phase increase, and the magnetostriction constant becomes smaller. The nitrogenation seems to offer a new way to obtain nanostructured ribbons. PACS No.: 75.70

scholarly journals Purification and properties of a phytase from Candida melibiosica 2491

2018 ◽  
Author(s):  
Danail Georgiev ◽  
Georgi Dobrev ◽  
Stefan Shilev
Keyword(s):  
Molecular Weight ◽  
Copper Ions ◽  
Phytase Activity ◽  
Gel Chromatography ◽  
Experimental Conditions ◽  
Cobalt Ions ◽  
Whole Cells ◽  
Inhibition Effect ◽  
Total Inhibition ◽  
Purification And Properties

Aim: To characterize the enzyme phytase produced by phytase-active Candida melibiosica 2491 for subsecuent use in feed industry. Methods: C. melibiosica 2491 had been selected among 118 strains as the most productive strain of phytase. In present study, the enzyme was first purified through electrophoresis grade in four steps: precipitation with organic solvent, ultrafiltration, gel chromatography and Denaturing gel electrophoresis (SDS–PAGE). Results: Higher levels of purification were obtained using ethanol. The gel chromatography showed an elution maximum at 11-12 fractions that characterize the corresponding one as high-molecular weight phytase. The purification level was found to be 19.5 folds with specific enzyme activity of 2.75 U/mg protein and yield – 19.64 %. Furthermore, the molecular weight of purified phytase was estimated to 35.9 кDa, with optimum of pH – at 4.5 and optimum of temperature at 55 °C. Maximum phytase activity in case of whole cells was found at 50 оС, which was less than using the purified enzyme. It was activated through 5 mM of Ba2+, 10 mM of Mn2+ and K+ ions. Total inhibition effect was achieved from Fe3+, Hg2+ and Zn2+. Copper ions (Cu2+) in concentrations at 5 mM conducted to partial inhibition effect, but at 10 mM the phytase activity was equal to zero. Low inhibition effect was determined in case of cobalt ions (Co2+) at concentrations of 10 mM. The phytase displayed broad sub­strate specificity and the Km for phytate was estimated to be 0.21 mM under the experimental conditions, while Vmax – 19.9 µМ/ml. Conclusion: Although the phytase produced by C. melibiosica 2491 is a promising enzyme to be used successfully in feed production, more investigations are needed to ensure its advantages.

Investigations on Cu2+-substituted Ni–Zn ferrite nanoparticles

2016 ◽  
Vol 30 (32n33) ◽  
pp. 1650347
Author(s):  
Amarjeet ◽  
Vinod Kumar
Keyword(s):  
Spinel Phase ◽  
Thermo Gravimetric Analysis ◽  
Peak Position ◽  
Precipitation Method ◽  
Gravimetric Analysis ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
X Ray ◽  
Zn Ferrite

[Formula: see text] ([Formula: see text] = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700[Formula: see text]C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz–5 MHz. Temperature dependence of the dielectric constant of [Formula: see text] was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz–5 MHz. It was found that the electrical conductivity decreases with increasing Cu[Formula: see text] ion content while it increases with the increase in temperature.

Magnetic properties of DyFe5−Co Al7: Suppression of exchange interactions and magnetocrystalline anisotropy by Co substitution

2018 ◽  
Vol 741 ◽  
pp. 715-722 ◽  
Author(s):  
D.I. Gorbunov ◽  
A.V. Andreev ◽  
D.S. Neznakhin ◽  
M.S. Henriques ◽  
J. Šebek ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetocrystalline Anisotropy ◽  
Exchange Interactions ◽  
Co Substitution
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