MAGNETIC STRUCTURE OF ZINC-FERRITE APPROACHING NANOMETER SIZES

2001 ◽  
Vol 15 (24n25) ◽  
pp. 3312-3316 ◽  
Author(s):  
A. H. MORRISH ◽  
Z. W. LI ◽  
J. Z. JIANG
Keyword(s):  
Magnetic Structure ◽  
Zinc Ferrite ◽  
Bulk Material ◽  
Spinel Ferrite ◽  
Average Particle Size ◽  
Average Particle ◽  
Octahedral Sites ◽  
Tetrahedral Sites ◽  
Zn Ferrite ◽  
Nanometer Particles

A unit cell of a spinel ferrite is just under 1 nm, actually about 0.8 nm. Particles approaching this size can be expected to possess properties that differ from the bulk material. Bulk polycrystalline Zn-ferrite ( ZnFe2O4 ) has been ball milled; after 50 h the average particle size is about 13 nm. The 57 Fe Mössbauer spectra at T = 4.2 K with and without a large (52 kOe) magnetic field applied longitudinally establish that the antiferromagnetic structure of the bulk has become ferrimagnetic in the ten nanometer particles via the transfer of some Zn cations from the A (tetrahedral) sites to the B (octahedral) sites. In addition, there is a large non-collinearity in the magnetic structure.

scholarly journals Structural and Electrical Properties of Nano [Ni 0.6 Zn 0.4 Fe2 O4] Spinel Ferrite

2021 ◽  
pp. 115-118
Author(s):  
Ramesh N. Taikar ◽  
Sadanand R. Sarve ◽  
Disha T. Yele ◽  
Deepak R. Taikar ◽  
Kalpana R. Nagde
Keyword(s):  
Electrical Properties ◽  
Spinel Ferrite ◽  
Sol Gel ◽  
Average Particle Size ◽  
Combustion Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zn Ferrite ◽  
Auto Combustion

Nano Ni-Zn ferrite with composition Ni 0.6 Zn 0.4 Fe2O4 is prepared by using sol-gel auto-combustion method with citric acid as a fuel. The structural properties of synthesized nano-ferrite is characterized by powder X-ray diffraction (XRD) technique while the electrical properties have been studied using two probe method. The X-ray diffraction study confirms that, there is a formation of single-phase cubic spinel with most intense peak at [311] having lattice constant of 8.3585 A0 and the average particle size is found to be 45.63 nm. In addition to this, the electrical resistivity of Ni-Zn Ferrite decreases with increase in temperature which exhibits semiconductor nature.

Influence of temperature and humidity on the angle of repose of wood bulk materials

2016 ◽  
Author(s):  
И.В. Бачериков ◽  
Б.М. Локштанов
Keyword(s):  
Field Experiments ◽  
Bulk Material ◽  
Average Particle Size ◽  
Operating Conditions ◽  
Angle Of Repose ◽  
Wood Dust ◽  
Average Particle ◽  
Bulk Materials ◽  
Technical Literature ◽  
The Impact

При проектировании открытых и закрытых хранилищ измельченных сыпучих материалов древесных материалов, таких как щепа и опилки, большое значение имеет угол естественного откоса (статический и динамический) этих материалов. В технической литературе приводятся противоречивые сведения о величине этих углов, что приводит к ошибкам при проектировании складов. В справочных данных не учитываются условия, в которых эксплуатируются емкости для хранения сыпучих материалов, свойства и состояние этих сыпучих материалов. В свою очередь, ошибки при проектировании приводят к проблемам (зависание, сводообразование, «затопление» и т. д.) и авариям при эксплуатации бункеров и силосов на производстве. В статье представлены сведения, посвященные влиянию влажности и температуры на угол естественного откоса сыпучих материалов. На основании лабораторных и натурных экспериментов, проведенных с помощью специально разработанных методик и установок, была скорректирована формула для определения углов естественного откоса (статического и динамического) для измельченных древесных материалов в зависимости от их фракционного и породного состава, влажности (абсолютной и относительной) и температуры. При помощи скорректированной формулы можно определить угол естественного откоса древесных сыпучих материалов со среднегеометрическим размером частицы от 0,5 мм до 15 мм (от древесной пыли до технологической щепы) в различных производственных условиях. Статья может быть полезна проектировщикам при расчете угла наклона граней выпускающей воронки бункеров и силосов предприятий лесной отрасли и целлюлозо-бумажной промышленности. In the design of open and closed storage warehouses chopped wood materials for bulk materials such as wood chips and sawdust, great importance has an angle of repose (static and dynamic) of these materials. In the technical literature are conflicting reports about the magnitude of these angles, which leads to errors in the design of warehouses. In the referencesdoes not take into account the conditions under which operated capacities for storage of bulk materials, and properties and condition of the bulk material. The design errors lead to problems (hanging, arching, «flooding», etc.) and accidents in the operation of hoppers and silos at the mills. The article provides information on the impact of humidity and temperature on the angle of repose of granular materials. On the basis of laboratory and field experiments, conducted with the help of specially developed techniques and facilities has been adjusted formula for determining the angle of repose (static and dynamic) for the shredded wood materials depending on their fractional and species composition, humidity (absolute and relative) and temperature. It is possible, by using the corrected formula, to determine the angle of repose of loose wood materials with average particle size of from 0.5 mm to 15 mm (wood dust to pulpchips) in various operating conditions. The article can be helpful to designers in the calculation of the angle of inclination of the funnel faces produces bunkers and silos forest industries and pulp and paper industry.

A Magnetically Ordered Non-Stoichiometric Zinc Ferrite for the Oxidative Dehydrogenation Reactions.

2001 ◽  
Vol 676 ◽  
Author(s):  
J. A. Toledo ◽  
N. Nava ◽  
X. C. Sun ◽  
X. Bokhimi
Keyword(s):  
Catalytic Activity ◽  
Oxidative Dehydrogenation ◽  
Spinel Structure ◽  
Zinc Ferrite ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Octahedral Sites ◽  
Tetrahedral Sites ◽  
Dehydrogenation Reactions ◽  
Hydrothermal Reduction

ABSTRACTZnFe2O4 nanoparticles were prepared by hydrothermal reduction approach. A considerable amount of α-Fe2O3 was segregated in the as-synthesized sample, which diffused into the tetrahedral and octahedral sites of the ZnFe2O4 spinel structure with increasing the annealing temperature. The introduction of Fe3+ into the tetrahedral positions was observed by Mössbauer spectra. Magnetization measurements showed an unusual ferrimagnetic behavior of the ZnFe2O4 phase, even at room temperature, confirming the introduction of Fe3+ into the tetrahedral sites of the spinel structure. Catalytic activity measured in the oxidative dehydrogenation of 1-butene reaction increased with increasing annealing temperature, indicating that those interactions of Fe3+ in tetrahedral and octahedral positions also promotes the activity and selectivity to butadiene formation.

scholarly journals Magnetic and Structural Studies of CoFe2O4Nanoparticles Suspended in an Organic Liquid

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Branka Babić-Stojić ◽  
Vukoman Jokanović ◽  
Dušan Milivojević ◽  
Zvonko Jagličić ◽  
Darko Makovec ◽  
...  
Keyword(s):  
Room Temperature ◽  
Bulk Material ◽  
Organic Liquid ◽  
Average Particle Size ◽  
Hydrodynamic Diameter ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Ferrite Nanoparticle ◽  
Nanoparticle System

We present a study of magnetic and structural properties of CoFe2O4nanoparticles suspended in an organic liquid. Transmission electron microscopy shows that the nanoparticles have a narrow size distribution of average particle size 5.9 ± 1.0 nm. X-ray diffraction shows that the particles are of cubic spinel crystal structure. Dynamic light scattering measurements reveal the existence of an organic shell around the CoFe2O4nanoparticles with an average hydrodynamic diameter of 14.4 nm. Coercive magnetic field atT=5 K is found to be 11.8 kOe. Disappearance of the coercive field and remanent magnetization at about 170 K suggests that the CoFe2O4nanoparticles are superparamagnetic at higher temperatures which is confirmed by the room temperature Mössbauer spectrum analysis. Saturation magnetization of the nanoparticles of 80.8 emu/g(CoFe2O4) at 5 K reaches the value detected in the bulk material and remains very high also at room temperature. The cobalt ferrite nanoparticle system synthesized in this work exhibits magnetic properties which are very suitable for various biomedical applications.

scholarly journals Fabrication and Magnetic Properties of Mn1 - xZnxFe2O4 (0 ≤ x ≤ 0.8) Nanoparticles

2009 ◽  
Vol 19 (1) ◽  
pp. 19-25
Author(s):  
Pham Hoai Linh ◽  
Tran Dang Thanh ◽  
Do Hung Manh ◽  
Nguyen Chi Thuan ◽  
Le Van Hong ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Biomedical Applications ◽  
Spinel Ferrite ◽  
Average Particle Size ◽  
Precipitation Method ◽  
Average Particle ◽  
Promising Candidate ◽  
Zn Concentration ◽  
Co Precipitation ◽  
Curie Temperature Tc

In this paper, we report results on the fabrication and magnetic properties of spinel ferrite Mn1-xZnxFe2O4 (0 ≤ x ≤ 0.8) nanoparticles. The nanoparticles were synthesized by a co-precipitation method. The effects of substituting Zn for Mn on the magnetic properties and particles size were focused. It was found that the phase-formation temperature is 90OC and the average particle size decreases from 40 nm to 10 nm when increased Zn concentration from zero to 0.8. The Curie temperature TC strongly decreases from 585 K (x = 0) to 320 K (x = 0.8) concomitantly with a decrease of the saturation magnetization MS. With a TC of 320 K and MS of 17 emu/g, the x=0.8 sample could be a promising candidate for some biomedical applications.

Structure and magnetic properties of 4H-SrMnO3-δ(δ=0.0 and 0.18) nanoparticles synthesized by thermal decomposition of appropriate precursor

2014 ◽  
Vol 1708 ◽  
Author(s):  
M. Parras ◽  
I. N. González-Jiménez ◽  
A. Torres-Pardo ◽  
A. E. Sánchez-Pelaez ◽  
A. Gutiérrez ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Structural Information ◽  
Bulk Material ◽  
Oxygen Deficiency ◽  
Average Particle Size ◽  
Reduction Process ◽  
High Energy ◽  
Structural Features ◽  
High Energy Resolution ◽  
Average Particle

ABSTRACTStoichiometric 4H-SrMnO3.0 nanoparticles have been successfully synthesized for the first time from thermal decomposition of a new heterometallic precursor [SrMn(edta)(H2O)5]·3/2H2O. From this precursor, highly homogeneous 4H-SrMnO3.0 nanoparticles with average particle size 70 nm are obtained. Local structural information, provided by atomically-resolved microscopy techniques, shows that 4H-SrMnO3.0 nanoparticles exhibit the same general structural features than the bulk material, although structural disorder, due to edge-dislocations, is observed. The nanometric size of particles enables a topotactic reduction process at low temperature stabilizing a metastable 4H-SrMnO2.82 phase. The oxygen deficiency is accommodated through extra cubic layers breaking the …hchc… 4H-sequence. These defect areas are Mn3+ rich as evidenced by high energy resolution EELS data. Magnetic characterization of nano-4H-SrMnO3-δ shows significant variations with respect to the bulk material.

scholarly journals Effect of zinc, magnesium, and copper substitutions on the initial permeability of nickel ferrite

2020 ◽  
Author(s):  
SAREH SHAFIEE ◽  
Ali Arab ◽  
NASTARAN RIAHI-NOURI
Keyword(s):  
Particle Size ◽  
Lattice Constant ◽  
Spinel Ferrite ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Average Crystallite Size ◽  
Initial Permeability ◽  
Gradient Force ◽  
Average Particle ◽  
Auto Combustion

Abstract Zinc, magnesium, and copper substituted nickel spinel ferrite were synthesized in the form of Ni1 − x (Zn06Mg0.2Cu0.2) x Fe2O4 (where x = 0.0, 0.3, 0.5 and 0.7) via auto combustion method. The effect of the presence of these dopants on the average of crystallite, average particle size, the lattice constant, morphology, initial permeability, and magnetization of the synthesized ferrites was investigated. The structural properties, morphology, and magnetic properties were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), LCR meter and alternative gradient force magnetometer (AGFM). XRD study shows the formation of a single-phase cubic spinel structure. Also, the average crystallite size was found to increase from 6 nm to 11 nm with increasing the Zn2+, Mg2+, and Cu2+ doping ratio from 0.0 to 0.7. Moreover, FE-SEM results were indicated the presence of nanosized spherical shape of prepared particles with agglomeration. The lattice constant and the particle size were found to increase with the increase in Zinc, magnesium, and copper. The values of initial permeability and magnetization were increased to a maximum value of 76 H/M and 71.37 emu/g for x = 0.7 sample. Furthermore, coercivity was found to decrease with increasing Zinc, magnesium, and copper concentration, which is useful for power applications. The variations of initial permeability and magnetization as a function of average particle size were discussed and were compared with previous works. The results were indicated the increase in initial permeability and magnetization with the enhancement of average particle size. The constancy in permeability throughout the frequency range studied from 10 kHz to1 MHz was indicated the compositional stability and quality of the samples. The results were indicated that the ferrites with high initial permeability can be an excellent choice as magnetic cores.

scholarly journals Synthesis of Green-Emitting Gd2O2S:Pr3+ Phosphor Nanoparticles and Fabrication of Translucent Gd2O2S:Pr3+ Scintillation Ceramics

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1639 ◽  
Author(s):  
Zhigang Sun ◽  
Bin Lu ◽  
Guiping Ren ◽  
Hongbing Chen
Keyword(s):  
Bulk Material ◽  
Average Particle Size ◽  
Green Emission ◽  
Chemical Precipitation ◽  
Ammonia Solution ◽  
Average Particle ◽  
Excitation Spectra ◽  
Flowing Hydrogen ◽  
Excited Luminescence ◽  
Uv Excitation

A translucent Gd2O2S:Pr ceramic scintillator with an in-line transmittance of ~31% at 512 nm was successfully fabricated by argon-controlled sintering. The starting precipitation precursor was obtained by a chemical precipitation route at 80 °C using ammonia solution as the precipitate, followed by reduction at 1000 °C under flowing hydrogen to produce a sphere-like Gd2O2S:Pr powder with an average particle size of ~95 nm. The Gd2O2S:Pr phosphor particle exhibits the characteristic green emission from 3P0,1→3H4 transitions of Pr3+ at 512 nm upon UV excitation into a broad excitation band at 285–335 nm arising from 4f2→4f5d transition of Pr3+. Increasing Pr3+ concentrations induce two redshifts for the two band centers of 4f2→4f5d transition and lattice absorption on photoluminescence excitation spectra. The optimum concentration of Pr3+ is 0.5 at.%, and the luminescence quenching type is dominated by exchange interaction. The X-ray excited luminescence spectrum of the Gd2O2S:Pr ceramic is similar to the photoluminescence behavior of its particle. The phosphor powder and the ceramic scintillator have similar lifetimes of 2.93–2.99 μs, while the bulk material has rather higher external quantum efficiency (~37.8%) than the powder form (~27.2%).

Effect of chromium substitution on crystal and lattice structure of soft manganese zinc ferrites

2017 ◽  
Vol 31 (14) ◽  
pp. 1750153 ◽  
Author(s):  
Anand Yadav ◽  
Dinesh Varshney
Keyword(s):  
Zinc Ferrite ◽  
Lattice Structure ◽  
Average Particle Size ◽  
Wave Number ◽  
Average Particle ◽  
Phonon Modes ◽  
Ionic Radii ◽  
Small Shift ◽  
Manganese Zinc ◽  
Manganese Zinc Ferrite

Chromium-doped manganese–zinc ferrite samples were prepared by solid-state reaction route to probe the effect of chromium ion on the crystal and lattice structure of mixed manganese–zinc ferrite. X-ray diffraction patterns reveal that Mn[Formula: see text]Zn[Formula: see text]Cr[Formula: see text]Fe[Formula: see text]O[Formula: see text] ([Formula: see text] = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) ferrite has polycrystalline cubic spinel structure with some secondary phase of [Formula: see text]–Fe[Formula: see text]O[Formula: see text]. The Raman spectra reveal four Raman active phonon modes in the measurement range of 200–750 cm[Formula: see text] with small shift in Raman modes towards higher wave number. The average particle size for Mn[Formula: see text]Zn[Formula: see text]Fe[Formula: see text]O[Formula: see text] is found to be 37.28 nm which reduces to 33.64 nm for Mn[Formula: see text]Cr[Formula: see text]Fe[Formula: see text]O[Formula: see text]. As the ion doping of chromium increases, the modes of vibration are found to shift towards higher wavelength and blueshift is attributed to the higher ionic radii of Cr[Formula: see text] as compared to Zn[Formula: see text].

scholarly journals Tunable heat generation in nickel-substituted zinc ferrite nanoparticles for effective magnetic hyperthermia

2021 ◽  
Author(s):  
Ralandinliu Kahmei ◽  
Papori Seal ◽  
Jyoti Prasad Borah
Keyword(s):  
Particle Size ◽  
Applied Field ◽  
High Performance ◽  
Cetyltrimethylammonium Bromide ◽  
Zinc Ferrite ◽  
Magnetic Nanoparticle ◽  
Average Particle Size ◽  
Magnetic Hyperthermia ◽  
Ferrite Nanoparticles ◽  
Average Particle

We report a high performance magnetic nanoparticle as hyperthermic agent under low applied field and frequency. CTAB (cetyltrimethylammonium bromide)-coated NixZn1-xFe2O4 nanoparticles of average particle size < 25 nm with various...

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