Magnetic and Catalytic Properties of Cu0.5Zn0.5Fe2O4 Nanocrystallite Powders

2006 ◽  
Vol 6 (1) ◽  
pp. 114-119 ◽  
Author(s):  
M. M. Rashad ◽  
M. H. Khedr ◽  
K. S. Abdel-Halim
Keyword(s):  
Magnetic Properties ◽  
Crystallite Size ◽  
Ferrous Sulfate ◽  
Average Crystallite Size ◽  
Sulfate Solution ◽  
Stoichiometric Ratio ◽  
Spent Catalyst ◽  
Hydrothermal Temperature ◽  
Iron And Steel ◽  
Average Size

Cu0.5Zn0.5Fe2O4 nanocrystallite powders (average size 13 nm) were synthesized from Cu–Zn spent catalyst (fertilizers) industries and ferrous sulfate wastes formed during iron and steel making. Cu–Zn catalyst (22.4% Cu and 26.4% Zn) was chemically treated with sulfuric acid at temperature 80 °C for 1 hr for the complete dissolving of copper and zinc into sulfate solution, then the produced solution was mixed with stoichiometric ratio of ferrous sulfate and the mixture was chemically precipitated as hydroxides followed by hydrothermal processing. The parameters affecting the magnetic properties and crystallite size of the produced ferrites powder e.g., temperature, time, and pH were systemically studied. X-ray diffraction analysis was used in order to determine the average crystallite size and phase identifications of the produced powder. The magnetic properties were studied by vibrating sample magnetometry. The results showed that the average crystallite size of the powder decreased for the ferrites powder formed at 150 °C and then increased by increasing the temperature to 200 °C. Interestingly, the saturation magnetization (Bs), remanent magnetization (Br) and coercive force (Hc) were 25.03 emu/g, 0.71 emu/g, and 4.83 Oe, respectively at hydrothermal temperature 150 °C for 24 hr and changed to 16.38 emu/g, 0.3864 emu/g, and 5.2 Oe at 150 °C and 72 hr. The produced nanoferrite powders are used for studying the catalytic activity of CO conversion to CO2 at different temperatures, pH and times. The maximum conversion (82%) is obtained at temperature 150 °C for 24 hrs and pH 12.

scholarly journals Structural and Magnetic Properties of Co‒Mn Codoped ZnO Nanoparticles Obtained by Microwave Solvothermal Synthesis

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 410 ◽  
Author(s):  
Jacek Wojnarowicz ◽  
Myroslava Omelchenko ◽  
Jacek Szczytko ◽  
Tadeusz Chudoba ◽  
Stanisław Gierlotka ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Crystallite Size ◽  
Doping Level ◽  
Solvothermal Synthesis ◽  
Zinc Acetate Dihydrate ◽  
Average Particle Size ◽  
Average Crystallite Size ◽  
Average Particle ◽  
Acetate Tetrahydrate ◽  
Preparation Methods

Zinc oxide nanoparticles codoped with Co2+ and Mn2+ ions (Zn(1−x−y)MnxCoyO NPs) were obtained for the first time by microwave solvothermal synthesis. The nominal content of Co2+ and Mn2+ in Zn(1−x−y)MnxCoyO NPs was x = y = 0, 1, 5, 10 and 15 mol % (the amount of both ions was equal). The precursors were obtained by dissolving zinc acetate dihydrate, manganese (II) acetate tetrahydrate and cobalt (II) acetate tetrahydrate in ethylene glycol. The morphology, phase purity, lattice parameters, dopants content, skeleton density, specific surface area, average particle size, average crystallite size, crystallite size distribution and magnetic properties of NPs were determined. The real content of dopants was up to 25.0% for Mn2+ and 80.5% for Co2+ of the nominal content. The colour of the samples changed from white to dark olive green in line with the increasing doping level. Uniform spherical NPs with wurtzite structure were obtained. The average size of NPs decreased from 29 nm to 21 nm in line with the increase in the dopant content. Brillouin type paramagnetism and an antiferromagnetic interaction between the magnetic ions was found for all samples, except for that with 15 mol % doping level, where a small ferromagnetic contribution was found. A review of the preparation methods of Co2+ and Mn2+ codoped ZnO is presented.

Magnetic Properties of the La0.50Ba0.50MnO3 Nanomanganites

2009 ◽  
Vol 152-153 ◽  
pp. 135-138 ◽  
Author(s):  
S.V. Trukhanov ◽  
A.V. Trukhanov ◽  
Christian E. Botez ◽  
H. Szymczak
Keyword(s):  
Magnetic Properties ◽  
Crystallite Size ◽  
Sol Gel ◽  
Exchange Interactions ◽  
Average Crystallite Size ◽  
Anomalous Behavior ◽  
Air Atmosphere ◽  
Crystallite Surface ◽  
Step Heat Treatment ◽  
Lattice Compression

Nanocrystalline La0.50Ba0.50MnO3 manganite was synthesized by an optimized sol-gel method. The initial sample was subjected to step-by-step heat treatment under air atmosphere. The ion stoichiometry, the morphology of crystallites of ceramics, and the magnetic properties were studied. It is established that the average crystallite size increases with increasing annealing temperature. All of the samples studied are characterized by a perovskite-like cubic structure, with the unit cell parameter a increasing continuously with the average crystallite size. The most significant lattice compression occurs in the sample with an average crystallite size of ~ 30 nm. The increase in the average crystallite size causes a nonmonotonic increase in the Curie temperature and in the spontaneous magnetic moment. The anomalous behavior of the magnetic properties of the La0.50Ba0.50MnO3 manganites obtained is explained by the competition between two size effects, namely, the frustration of the indirect exchange interactions Mn3+ – O – Mn4+ on the nanocrystallite surface and the crystal lattice compression due to the crystallite surface tension.

High-Energy Ball Milling Conditions in Formation of NiTiCu Shape Memory Alloys

2021 ◽  
pp. 1-7
Author(s):  
Tomasz Goryczka ◽  
Piotr Salwa ◽  
Maciej Zubko
Keyword(s):  
Chemical Composition ◽  
Shape Memory ◽  
Crystallite Size ◽  
Ball Milling ◽  
Average Crystallite Size ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Energy Ball ◽  
Average Size ◽  
Grinding Time

The properties and the shape memory effect depend, among other things, on chemical composition, as well as the method of shape memory alloy (SMA) production. One of the manufacturing methods that leads to the amorphous/nanocrystalline SMA is high-energy ball milling combined with annealing. Using this technique, an SMA memory alloy, with the nominal chemical composition of Ni25Ti50Cu25, was produced from commercial elemental powders (purity −99.7%). The structure and morphology were characterized (at the various stages of its production) by the use of X-ray diffraction, as well as electron microscopy (both scanning and transmission). Choosing the appropriate grinding time made it possible to produce an NiTiCu alloy with a different crystallite size. Its average size changed from 6.5 nm (after 50 h) to about 2 nm (100 h). Increasing the grinding time up to 140 h resulted in the formation of areas that showed the B19 martensite and the Ti2(Ni,Cu) phase with the average crystallite size of about 6 nm (as milled). After crystallization, the average size increased to 11 nm.

MAGNETIC PROPERTIES OF NANOCRYSTALLINE NiFe2O4 POWDERS PREPARED BY AN AQUEOUS OXIDATIVE PRECIPITATION PROCESS

2001 ◽  
Vol 15 (03) ◽  
pp. 305-312 ◽  
Author(s):  
M. RAJENDRAN ◽  
A. K. BHATTACHARYA ◽  
D. DAS ◽  
S. N. CHINTALAPUDI ◽  
C. K. MAJUMDAR
Keyword(s):  
Magnetic Properties ◽  
Hyperfine Field ◽  
Crystallite Size ◽  
Room Temperature ◽  
Magnetic Hyperfine Field ◽  
Average Crystallite Size ◽  
Precipitation Process ◽  
Saturation Magnetisation ◽  
Crystallite Sizes ◽  
Oxidative Precipitation

Nanocrystalline NiFe 2 O 4 powder has been prepared by an oxidative precipitation process at room-temperature and the crystallite size dependent magnetic properties have been studied. The NiFe 2 O 4 powders prepared at room-temperature had an average crystallite size of 6 nm and showed a reduced saturation magnetisation (M s ) of 3 emu · g -1. The crystallite size was increased by heating the samples to increasingly higher temperatures. The M s value increased from 3 to 40 emu·g -1 as the crystallite size was increased from 6 to 120 nm. The samples having crystallite sizes from 6 to 20 nm were superparamagnetic at room-temperature. The Mössbauer spectrum of the 6 nm sized sample showed a broad quadruple doublet, whereas, the 40 nm sized sample showed a clear sextet pattern, with a hyperfine field values of 466 and 504 kOe for A(tetraheral) and B(octahedral) sublattices, respectively. It is shown that the saturation magnetisation and magnetic hyperfine field values are significantly reduced in nanocrystalline NiFe 2 O 4 as a function of crystallite size.

Tuning of Magnetic Properties in Cobalt-Doped Nanocrystalline Bismuth Ferrite

2011 ◽  
Vol 1368 ◽  
Author(s):  
Gina Montes Albino ◽  
Oscar Perales-Pérez ◽  
Boris Renteria ◽  
Marco Galvez ◽  
Maxime J-F Guinel
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Crystallite Size ◽  
Bismuth Ferrite ◽  
Average Crystallite Size ◽  
Fine Tuning ◽  
Free Standing ◽  
Cobalt Ions ◽  
Polyol Medium ◽  
Co Doped

ABSTRACTThis study reports on the structural and magnetic characterizations of free-standing bismuth ferrite, BiFeO3, nanoparticles synthesized in polyol medium. Fine tuning of the ferrite magnetic properties was achieved by adding an excess bismuth species or doping with cobalt ions, coupled with thermal annealing. Crystalline Bi1-yCoyFeO3 powders (where ‘y’ ranges from 0.00 to 0.10) were produced after annealing the precursors for one hour at 700οC. The average crystallite size was calculated to be approximately 22 nm. We found that the synthesis under stoichiometric excess of Bi species (up to 10 at.%) promoted a more complete crystallization of the material, i.e., no precursor phases remained. Furthermore, both the saturation magnetization and the coercivity of the synthesized powders were strongly influenced by the concentration of Co. They increased from 0.13 emu/g and 19 Oe to 3.5 emu/g and 1183 Oe for pure BiFeO3 and 10 at.% Co-doped BiFeO3, respectively.

scholarly journals The Structural and Magnetic Properties of Gadolinium Doped CoFe2O4Nanoferrites

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Qing Lin ◽  
Jinpei Lin ◽  
Yun He ◽  
Ruijun Wang ◽  
Jianghui Dong
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Crystallite Size ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Structural And Magnetic Properties

Gadolinium substituted cobalt ferrite CoGdxFe2−xO4(x= 0, 0.04, 0.08) powders have been prepared by a sol-gel autocombustion method. XRD results indicate the production of a single cubic phase of ferrites. The lattice parameter increases and the average crystallite size decreases with the substitution of Gd3+ions. SEM shows that the ferrite powers are nanoparticles. Room temperature Mössbauer spectra of CoGdxFe22−xO4are two normal Zeeman-split sextets, which display ferrimagnetic behavior. The saturation magnetization decreases and the coercivity increases by the Gd3+ions.

Effect performance of the nanomagnetic properties of Ni–Cu–Co ferrites by Al3+ ions adulteration

2020 ◽  
Vol 34 (05) ◽  
pp. 2050059 ◽  
Author(s):  
Nanzhaxi Suo ◽  
Aimin Sun ◽  
Lichao Yu ◽  
Zhuo Zuo ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Properties ◽  
Fourier Transform ◽  
Crystallite Size ◽  
Spinel Structure ◽  
Average Crystallite Size ◽  
Doping Amount ◽  
X Ray ◽  
Transmission Electron

In this paper, aluminum-doped Ni–Cu–Co ferrite nanomagnetic material powder was prepared by sol–gel technique using citric acid as a complexing agent and high-purity nitrate as raw material. The effect of doping amount of different Al[Formula: see text] ions on the structure and magnetic properties of ferrites has been studied. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX) and Vibrating sample magnetometer (VSM) were used to characterize the structural and magnetic properties of ferrite. The XRD analysis showed that all samples of Ni–Cu–Co ferrites have a single-phase cubic spinel structure. Average crystallite size was calculated by the Debye–Scherrer formula and it was found that the average crystallite size of the sample was affected by the doping concentration. As the amount of Al[Formula: see text] ion doping increases, the crystallite size decreases from 54.88 nm to 46.09 nm. The absorption peak of Fourier transform infrared spectroscopy (FTIR) at 590 cm[Formula: see text] further indicates the formation of cubic spinel structure of Ni–Cu–Co ferrite. Transmission electron microscopy (TEM) images show the presence of particles which are spherically cubic-shaped particles. The constituent elements of the samples were analyzed by EDX spectroscopy. In addition, the ferromagnetism of the samples was confirmed by VSM measurements. The saturation magnetization (Ms) and remanent magnetization (Mr) first increase and then decrease when the aluminum ion concentration increases. Compared with pure samples and other doped samples, they have the best magnetic properties when the doping amount of Al[Formula: see text] ions is [Formula: see text]. It also shows that the prepared samples are suitable for magnetic recording materials.

scholarly journals The Influence of Co-Precipitation Technique on the Structure, Morphology and Dual-Modal Proton Relaxivity of GdFeO3 Nanoparticles

Inorganics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 39
Author(s):  
Yamen Albadi ◽  
Maria S. Ivanova ◽  
Leonid Y. Grunin ◽  
Kirill D. Martinson ◽  
Maria I. Chebanenko ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Relaxation Times ◽  
Average Crystallite Size ◽  
Nitrogen Adsorption ◽  
Mri Contrast Agents ◽  
Colloidal Solutions ◽  
Characteristic Particle ◽  
Diffraction Patterns ◽  
Co Precipitation ◽  
Average Size

Nanocrystals of gadolinium orthoferrite (GdFeO3) with morphology close to isometric and superparamagnetic behavior were successfully synthesized using direct, reverse and microreactor co-precipitation of gadolinium and iron(III) hydroxides with their subsequent heat treatment in the air. The obtained samples were investigated by PXRD, FTIR, low-temperature nitrogen adsorption-desorption measurements, HRTEM, SAED, DRS and vibration magnetometry. According to the X-ray diffraction patterns, the GdFeO3 nanocrystals obtained using direct co-precipitation have the smallest average size, while the GdFeO3 nanocrystals obtained using reverse and microreactor co-precipitation have approximately the same average size. It was shown that the characteristic particle size values are much larger than the corresponding values of the average crystallite size, which indicates the aggregation of the obtained GdFeO3 nanocrystals. The GdFeO3 nanocrystals obtained using direct co-precipitation aggregate more than the GdFeO3 nanocrystals obtained using reverse co-precipitation, which, in turn, tend to aggregate more strongly than the GdFeO3 nanocrystals obtained using microreactor co-precipitation. The bandgap of the obtained GdFeO3 nanocrystals decreases with decreasing crystallite size, which is apparently due to their aggregation. The colloidal solutions of the obtained GdFeO3 nanocrystals with different concentrations were investigated by 1H NMR to measure the T1 and T2 relaxation times. Based on the obtained r2/r1 ratios, the GdFeO3 nanocrystals obtained using microreactor, direct and reverse co-precipitation may be classified as T1, T2 and T1–T2 dual-modal MRI contrast agents, respectively.

Effect of Different Synthesis Methods on Structural, Morphological and Magnetic Properties of La0.7Ba0.25Nd0.05MnO3

2020 ◽  
Vol 860 ◽  
pp. 89-94
Author(s):  
Dicky Rezky Munazat ◽  
Budhy Kurniawan ◽  
Dhawud Sabilur Razaq ◽  
Ikhwan Nur Rahman ◽  
Arief Sudarmaji ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Crystallite Size ◽  
Sol Gel ◽  
Magnetic Hysteresis ◽  
Double Exchange ◽  
Average Crystallite Size ◽  
Rhombohedral Structure ◽  
Hysteresis Curve ◽  
Synthesis Methods ◽  
Double Exchange Interaction

La0.7Ba0.25Nd0.05MnO3 (LBNMO) compounds were synthesized using two different methods, namely are solid-state reaction (SS) and sol-gel (SG). All samples were heat-treated at 1200 °C for 12 hours. The investigation on structural, morphological, and magnetic properties was carried out by X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM), and Vibrating Samples Magnetometer (VSM) at room temperature. From the Rietveld refinement, both samples have formed a rhombohedral structure with an R-3c (167) space group. The average crystallite size was calculated using the Scherrer formula and Williamson-Hall (W-H) method for comparison. It was shown that the crystallite size of the sample produced by the SG method has larger than the SS method. This result is fairly consistent with the result obtained from SEM analysis, which shows that the average grain for the SG sample is larger than of the grain of the SS samples. From the magnetic hysteresis curve, the magnetization saturation value for the SG was higher and sharper than that of the SS sample. These confirm the occurrence of the double exchange interaction in the samples, which is mainly associated with the reduction of bandwidth and grain size.

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