scholarly journals Structural Analysis and Magnetic Properties of FeCo Alloys Obtained by Mechanical Alloying

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
F. Sánchez-De Jesús ◽  
A. M. Bolarín-Miró ◽  
C. A. Cortés Escobedo ◽  
G. Torres-Villaseñor ◽  
P. Vera-Serna
Keyword(s):  
Magnetic Properties ◽  
Mechanical Alloying ◽  
Room Temperature ◽  
Intermetallic Phase ◽  
Weight Ratio ◽  
Hardened Steel ◽  
Specific Saturation Magnetization ◽  
Maximum Value ◽  
Feco Alloys ◽  
Almost All

A systematic study on the structural and magnetic properties of Fe100-xCox alloys (10<x<90, Δx=10 in wt. percent) obtained by mechanical alloying is presented. Elemental powders of Fe and Co mixed in an adequate weight ratio were milled at room temperature in a shaker mixer mill using vials and balls of hardened steel as milling media with a ball : powder weight ratio of 12 : 1. The mixtures were milled for 3 h. The results show that, after milling, for almost all the composition (up to x=60), solid solutions based on bcc structures were obtained. For Co-rich alloys (x≥70), different phases were found, revealing the formation of a metastable intermetallic phase (FeCo, wairauite) together with fcc-Co and hcp-Co phases. The specific saturation magnetization increases by increasing Co content, reaching a maximum value of 225 emu/g for hcp-Fe70Co30, and then it shows a diminution up to 154 emu/g for bcc-Fe30Co70. All studied alloys (Fe100-xCox) present low coercivity, in the range from 0 to 65 Oe, which is lower than reported. The coercivity increases with the increment in Co, reaching a maximum of 64.1 Oe for Fe40Co60. After that, the coercivity falls up to 24.5 Oe for Co-rich alloys, which make them a very low coercive material.

Microstructural and Magnetic Properties of Nanostructured Fe65Co35 Powders Prepared by Mechanical Alloying

2013 ◽  
Vol 829 ◽  
pp. 778-783 ◽  
Author(s):  
Mohsen Razi ◽  
Ali Ghasemi ◽  
Gholam Hossein Borhani
Keyword(s):  
Magnetic Properties ◽  
Mechanical Alloying ◽  
Milling Time ◽  
Cooling System ◽  
Average Particle Size ◽  
Weight Ratio ◽  
Lattice Parameter ◽  
Milling Process ◽  
Protective Atmosphere ◽  
Average Particle

Nanostructured Fe65Co35 alloy powders were fabricated by mechanical alloying in an attritor mill with different milling times. The milling process carried out in speed of 350 rpm, with 20:1 ball to powder weight ratio and under argon protective atmosphere. A continuous cooling system applied to avoid increasing temperature during the milling. The effect of milling time on structural and magnetic properties investigated by X-ray diffraction, scanning electron microscopy and vibration sample magnetometer. According to the obtained results, nanostructured Fe65Co35 solid solution powders resulted with an average particle size of 400 nm and crystallite size of 6.8 nm by milling for 20 hours. With increasing the milling time, the lattice parameter decreased and the lattice strain increased for Fe65Co35 powders. The maximum saturation magnetization with 1311 emu/cc value and the minimum coercivity with 22 Oe value occurs after milling for 15 hours.

scholarly journals Structure and Ferromagnetism in Carbon Nanofibers from PAN/PVP

2021 ◽  
Author(s):  
Suminya - Teeta ◽  
Somchai - Sonsupap ◽  
Ratchaneekorn - Wanchanthuek ◽  
Santi - Maensiri ◽  
Narong - Chanlek ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Carbon Nanofibers ◽  
Chemical Bonding ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
New Technologies ◽  
Room Temperature Ferromagnetism ◽  
Weight Ratio ◽  
Average Diameter ◽  
X Ray

Abstract We report on the room-temperature ferromagnetism in carbon nanofibers. Carbon nanofibers were fabricated using sequential electrospinning of polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP). The morphologies, crystal structures, chemical bonding states and magnetic properties were characterized for three different polyacrylonitrile (PAN) to polyvinylpyrrolidone (PVP) weight ratios (10:0, 7:3 and 6:4) of PAN/PVP. The as-spun PAN/PVP were carbonized in three steps; stabilization, carbonization and activation at 800 ºC to obtain carbon nanofibers. The morphology and structure of the carbon nanofibers (CNFs) were completely characterized by field emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD) and Raman spectroscopy. The elemental composition and the chemical bonding of CNFs were analyzed by x-ray photoelectron spectroscopy (XPS), the magnetic properties of CNFs were measured by vibrating sample magnetometer (VSM) at room-temperature. XRD patterns showed the phase of amorphous carbon structure. The average diameter sizes of the carbon nanofibers ranged from 340 to 484 nm. Raman analysis was used to determine the carbon qualities in the samples by the numbers of sp3/sp2 hybridized atoms. Chemical analysis with XPS indicated that there were no magnetic contaminants in the samples. The PAN/PVP weight ratio of 6:4 showed ferromagnetic carbon nanofibers with the highest specific magnetization as ~144.2 memu/g at 300 K. These results inspire us to further research the potential of carbon materials, as a completely new class of magnetic devices. This will aid the development of new technologies in the near future.

Synthesis, Microstructure and Magnetic Properties of Nanocrystalline Ni-Zn Ferrite by a Modified Wet Chemical Method

2008 ◽  
Vol 368-372 ◽  
pp. 594-597
Author(s):  
Yin Liu ◽  
Tai Qiu
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Wet Chemical Method ◽  
Specific Saturation Magnetization ◽  
Random Anisotropy ◽  
Zn Ferrite ◽  
Wet Chemical ◽  
Critical Grain Size ◽  
Microstructure And Magnetic Properties

Nanocrystalline Ni1-xZnxFe2O4 ferrites with 0 ≤ x ≤ 1 were prepared by sprayingcoprecipitation method. The microstructure was investigated by TG-DSC, XRD, SEM, TEM and BET. Magnetic properties were measured with vibrating sample magnetometer at room temperature. The results showed that uniform and fine nanocrystalline Ni1-xZnxFe2O4 ferrites are obtained. The grain size of sample calcined at 600°C for 1.5h is about 30nm. There are a few agglomerates with average sizes below 100nm. The specific saturation magnetization, Ms, of the sample increases with increasing Zn2+ concent x at room temperature, and the maximum Ms is 66.8 A·m2·kg-1 as the Zn2+ content x is around 0.5mol. As calcining temperature increased from 400°C to 1050°C, the Ms of Ni0.5Zn0.5Fe2O4 ferrite increases from 40.2 A·m2·kg-1 to 75.6 A·m2·kg-1. The coercivity maximum is about 5.97 kA·m-1 as its critical grain size is about 62.0nm. The relation between coercivity and grain size for nanocrystalline Ni0.5Zn0.5Fe2O4 ferrite may be explained based on random anisotropy theory.

The effect of Oxygen partial pressure during deposition in the magnetic properties of ZnO thin film

2011 ◽  
Vol 1292 ◽  
Author(s):  
Anis Biswas ◽  
Wang Shirong ◽  
Sandeep Nagar ◽  
L. Belova ◽  
K. V. Rao
Keyword(s):  
Magnetic Properties ◽  
Total Pressure ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Zno Thin Films ◽  
Zno Thin Film ◽  
Xrd Study ◽  
Maximum Value ◽  
Partial Pressures ◽  
Effect Of Oxygen

ABSTRACTWe have studied the magnetic properties of 100 nm thick ZnO thin films prepared by magnetron sputtering in different oxygen partial pressures (ratio of oxygen pressure to total pressure in deposition chamber, POxy). Only the films fabricated at POxy below ~ 0.5 show room temperature ferromagnetism. The saturation magnetization at room temperature is initially found to increase as POxy increases and reaches maximum value of ~ 5 emu/gm at POxy ~ 0.3 and then starts to decrease and becomes diamagnetic for POxy > 0.5. From small angle XRD study of structural properties of the films, we find that the lattice stress developed in the film along c-axis also exhibits a similar behavior with the variation of POxy. Thus, both the room temperature ferromagnetism and lattice stress appear to originate from the intrinsic defects present in the sample.

Giant Magnetocaloric Effect in the Region of Magnetic Phase Transition in Mn (As,Sb) Compounds

2012 ◽  
Vol 190 ◽  
pp. 343-346 ◽  
Author(s):  
N.Yu. Pankratov ◽  
V.I. Mitsiuk ◽  
A.I. Krokhotin ◽  
A.I. Smarzhevskaya ◽  
G.A. Govor ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Magnetic Phase ◽  
Small Concentration ◽  
Maximum Value ◽  
Giant Magnetocaloric Effect ◽  
Magnetic Filed ◽  
Direct Investigation

The MCE in MnAs and doped Mn (As,Sb) compounds with low concentration of Sb has been studied by direct investigation. It was shown that for MnAs the maximum value of MCE is ΔT = 0.28 K on heating (at 308 K) and ΔT = 0.88 K on cooling (at T = 306 K) in magnetic filed 12.5 kOe. In doped Mn (As,Sb) compounds the temperature dependence of MCE is similar to MnAs. All investigated compounds demonstrate a strong temperature and field hysteresis of magnetic properties in magnetic field less than 40 kOe. It was established that a small concentration of Sb leads to decrease of MCE hysteresis and preserves the phase transition at room temperature region.

Microstructure of mechanically alloyed and hot-pressed Al5CuZr2

1990 ◽  
Vol 48 (4) ◽  
pp. 970-971
Author(s):  
T. E. Mitchell ◽  
P. B. Desch ◽  
R. B. Schwarz
Keyword(s):  
Mechanical Alloying ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Rapid Quenching ◽  
Hardened Steel ◽  
Alloyed Powder ◽  
Ion Milling ◽  
Mechanical Grinding ◽  
Mechanically Alloyed ◽  
Steel Container

Al3Zr has the highest melting temperature (1580°C) among the tri-aluminide intermetal1ics. When prepared by casting, Al3Zr forms in the tetragonal DO23 structure but by rapid quenching or by mechanical alloying (MA) it can also be prepared in the metastable cubic L12 structure. The L12 structure can be stabilized to at least 1300°C by the addition of copper and other elements. We report a TEM study of the microstructure of bulk Al5CuZr2 prepared by hot pressing mechanically alloyed powder.MA was performed in a Spex 800 mixer using a hardened steel container and balls and adding hexane as a surfactant. Between 1.4 and 2.4 wt.% of the hexane decomposed during MA and was incorporated into the alloy. The mechanically alloyed powders were degassed in vacuum at 900°C. They were compacted in a ram press at 900°C into fully dense samples having Vickers hardness of 1025. TEM specimens were prepared by mechanical grinding followed by ion milling at 120 K. TEM was performed on a Philips CM30 at 300kV.

STRUCTURAL CHARACTERIZATION, PREPARATION AND MAGNETIC PROPERTIES OF SEVERAL ROOM-TEMPERATURE MAGNETIC OXIDES WITH THE PEROVSKITE-LIKE STRUCTURE

1977 ◽  
Vol 38 (C1) ◽  
pp. C1-95-C1-101 ◽  
Author(s):  
B. BOCHU ◽  
M. N. DESCHIZEAUX ◽  
J. C. JOUBERT ◽  
J. CHENAVAS ◽  
A. COLLOMB ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Structural Characterization ◽  
Room Temperature ◽  
Magnetic Oxides

Photoluminescence and Magnetic Properties of Undoped and (Mn, Co) co-doped ZnO Nanoparticles

2020 ◽  
Vol 16 (4) ◽  
pp. 655-666
Author(s):  
Mona Rekaby
Keyword(s):  
Magnetic Properties ◽  
Zno Nanoparticles ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Structural Defects ◽  
Ferromagnetic Behavior ◽  
Secondary Phases ◽  
Antiferromagnetic Ordering ◽  
Doped Zno ◽  
Co Doped

Objective: The influence of Manganese (Mn2+) and Cobalt (Co2+) ions doping on the optical and magnetic properties of ZnO nanoparticles was studied. Methods: Nanoparticle samples of type ZnO, Zn0.97Mn0.03O, Zn0.96Mn0.03Co0.01O, Zn0.95Mn0.03 Co0.02O, Zn0.93Mn0.03Co0.04O, and Zn0.91Mn0.03Co0.06O were synthesized using the wet chemical coprecipitation method. Results: X-ray powder diffraction (XRD) patterns revealed that the prepared samples exhibited a single phase of hexagonal wurtzite structure without any existence of secondary phases. Transmission electron microscope (TEM) images clarified that Co doping at high concentrations has the ability to alter the morphologies of the samples from spherical shaped nanoparticles (NPS) to nanorods (NRs) shaped particles. The different vibrational modes of the prepared samples were analyzed through Fourier transform infrared (FTIR) measurements. The optical characteristics and structural defects of the samples were studied through Photoluminescence (PL) spectroscopy. PL results clarified that Mn2+ and Co2+ doping quenched the recombination of electron-hole pairs and enhanced the number of point defects relative to the undoped ZnO sample. Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM). (Mn, Co) co-doped ZnO samples exhibited a ferromagnetic behavior coupled with paramagnetic and weak diamagnetic contributions. Conclusion: Mn2+ and Co2+ doping enhanced the room temperature Ferromagnetic (RTFM) behavior of ZnO. In addition, the signature for antiferromagnetic ordering between the Co ions was revealed. Moreover, a strong correlation between the magnetic and optical behavior of the (Mn, Co) co-doped ZnO was analyzed.

Effect of Annealing temperature on the Structural and Magnetic Properties of TbxY3-xFe5O12(x = 0.0, 1.0, 2.0) Thin Films Prepared by Sol-Gel Process

2012 ◽  
Vol 501 ◽  
pp. 236-241 ◽  
Author(s):  
Ftema W. Aldbea ◽  
Noor Bahyah Ibrahim ◽  
Mustafa Hj. Abdullah ◽  
Ramadan E. Shaiboub
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Vibrating Sample Magnetometer ◽  
X Ray ◽  
Garnet Phase ◽  
Sol Gel Process ◽  
Amorphous Structures

Thin films nanoparticles TbxY3-xFe5O12 (x=0.0, 1.0, 2.0) were prepared by the sol-gel process followed by annealing process at various annealing temperatures of 700° C, 800° C and 900° C in air for 2 h. The results obtained from X-ray diffractometer (XRD) show that the films annealed below 900°C exhibit peaks of garnet mixed with small amounts of YFeO3 and Fe2O3. Pure garnet phase has been detected in the films annealed at 900°C. Before annealing the films show amorphous structures. The particles sizes measurement using the field emission scanning electron microscope (FE-SEM) showed that the particles sizes increased as the annealing temperature increased. The magnetic properties were measured at room temperature using the vibrating sample magnetometer (VSM). The saturation magnetization (Ms) of the films also increased with the annealing temperature. However, different behavior of coercivity (Hc) has been observed as the annealing temperature was increased.

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