The Role of Disorder in the Magnetic Properties of Mechanically Milled Nanostructured Alloys

2001 ◽  
Vol 674 ◽  
Author(s):  
Diandra L. Leslie-Pelecky ◽  
Elaine M. Kirkpatrick ◽  
Tom Pekarek ◽  
Richard L. Schalek ◽  
Paul Shand ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Spin Glass ◽  
Defect Formation ◽  
Fold Increase ◽  
Nanostructured Alloys ◽  
Glassy Behavior ◽  
Mean Grain Size ◽  
20 Nm

ABSTRACTMechanical milling provides a unique means of studying the influence of grain size and disorder on the magnetic properties of nanostructured alloys. This paper compares the role of milling in the nanostructure evolution of two ferromagnets – SmCo5 and GdAl2 – and the subsequent impact of nanostructure on magnetic properties and phase transitions. The ferromagnetic properties of SmCo5 are enhanced by short (< 2 hours) milling times, producing up to an eight-fold increase in coercivity and high remanence ratios. The coercivity increase is attributed to defect formation and strain. Additional milling increases the disorder and produces a mix of ferromagnetic and antiferromagnetic interactions that form a magnetically glassy phase. GdAl2, which changes from ferromagnetic in its crystalline form to spin-glass-like in its amorphous form, is a model system for studying the dependence of magnetically glassy behavior on grain size and disorder. Nanostructured GdAl2 with a mean grain size of 8 nm shows a combination of ferromagnetic and magnetically glassy behavior, in contrast to previous studies of nanostructured GdAl2 with a grain size of 20 nm that show only spin-glass-like behavior.

Magnetic behaviors of Ti50Zr33Ni17 quasicrystals measured by VSM

2009 ◽  
Vol 224 (1-2) ◽  
Author(s):  
Yunman Lee ◽  
Jae-kyun Jeon ◽  
Hyemin Shin ◽  
Jae-yong Kim
Keyword(s):  
Magnetic Properties ◽  
Spin Glass ◽  
Rapid Quenching ◽  
Aperiodic Structure ◽  
Quenching Method ◽  
Magnetic States

AbstractQuasicrystals made with Ti, Zr and Ni are good candidate materials studying the magnetic properties of aperiodic structure because the role of Ni in stabilization of the quasicrystal phase is important. Various magnetic states in quasicrystals have been reported including diamagnetism, paramagnetism, spin glass, ferromagnetism and ferrimagnetism. We prepared Ti–Zr–Ni quasicrystals by rapid quenching method. The magnetization (

Superplasticity and Microstructure Evolution of Electrodeposited Nanocrystalline Nickel

2007 ◽  
Vol 551-552 ◽  
pp. 539-544 ◽  
Author(s):  
S. Ding ◽  
Kai Feng Zhang ◽  
Guo Feng Wang
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Room Temperature ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Intergranular Cracking ◽  
Mean Grain Size ◽  
Electrodeposited Nickel ◽  
Superplastic Properties

Nanocrystalline pure nickel (nc-Ni) was produced by pulse electrodeposition and its superplastic properties at and above room temperature were investigated. The electrodeposited nickel has a narrow grain size distribution with a mean grain size of 70nm. Uniaxial tensile tests at room temperature showed that nc-Ni has a limited plasticity but high tensile strength up to 1GPa at strain rates between 10-5 and 10-2s-1. However, when the temperature increased to 420 and higher, test specimens showed uniform deformation and the elongation value was larger than 200%. A maximum elongation value of 380% was observed at 450°C and a strain rate of 1.67x10-3s-1, SEM and TEM were used to examine the microstructures of the as-deposited and deformed specimens. The results indicated that fracture was caused by intergranular cracking and most cracks were originated from the brittle oxide formed during the tensile test. Grain coarsening was observed in the deformed specimen. The role of temperature and strain on grain growth was evaluated by comparing the microstructure of deformed samples with that of samples statically annealed. Deformation mechanism was discussed based upon the deformed microstructure and strain rate jump tests.

Role of grain size on the magnetic properties of La0.7Sr0.3MnO3

2013 ◽  
Vol 328 ◽  
pp. 86-90 ◽  
Author(s):  
P.A. Yadav ◽  
A.V. Deshmukh ◽  
K.P. Adhi ◽  
B.B. Kale ◽  
N. Basavaih ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties

AN INVESTIGATION OF THE INFLUENCE OF CLIMATIC FACTORS ON THE EROSIVE WEAR KINETICS OF POLYMER COATINGS

Tribologia ◽  
2016 ◽  
Vol 268 (4) ◽  
pp. 115-125
Author(s):  
Danuta KOTNAROWSKA ◽  
Andrzej KOTNAROWSKI
Keyword(s):  
Grain Size ◽  
Climatic Factors ◽  
High Surface ◽  
Surface Hardness ◽  
Surface Profile ◽  
Erosive Wear ◽  
Epoxy Coatings ◽  
Mean Grain Size ◽  
Resistance Decrease ◽  
20 Nm

The paper presents investigation results concerning the influence of the modification with nanoparticles of silica (of mean grain size 12 nm or 20 nm) or aluminium trioxide (20 nm) of the structure of epoxy coatings on their resistance to climatic factors and the action of erosive particles. Epoxy coatings aged in natural climatic conditions showed an erosive resistance decrease with ageing. The erosive resistance decrease was accompanied by a hardness decrease as well as surface roughness increase. The highest resistance to erosive wear after 3 years of ageing revealed coatings modified with aluminium trioxide nanoparticles, while the lowest one showed coatings modified with silica nanoparticles of 12 nm mean grain size. Nanocoatings modified with aluminium trioxide nanoparticles also had the highest resistance to ageing; which was proven by the lowest increase of Ra and Rz surface profile parameter values with time, as well as by a high surface hardness, which was higher than hardness of new unmodified coatings.

scholarly journals The Magnetic Properties of Fe/Cu Multilayered Nanowires: The Role of the Number of Fe Layers and Their Thickness

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2729
Author(s):  
Sofia Caspani ◽  
Suellen Moraes ◽  
David Navas ◽  
Mariana P. Proenca ◽  
Ricardo Magalhães ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Segment Length ◽  
Magnetic Reversal ◽  
Micromagnetic Simulations ◽  
Cu Nanowires ◽  
Alumina Membranes ◽  
Magnetic Layers ◽  
20 Nm ◽  
Multilayered Nanowires

Multi-segmented bilayered Fe/Cu nanowires have been fabricated through the electrodeposition in porous anodic alumina membranes. We have assessed, with the support of micromagnetic simulations, the dependence of fabricated nanostructures’ magnetic properties either on the number of Fe/Cu bilayers or on the length of the magnetic layers, by fixing both the nonmagnetic segment length and the wire diameter. The magnetic reversal, in the segmented Fe nanowires (NWs) with a 300 nm length, occurs through the nucleation and propagation of a vortex domain wall (V-DW) from the extremities of each segment. By increasing the number of bilayers, the coercive field progressively increases due to the small magnetostatic coupling between Fe segments, but the coercivity found in an Fe continuous nanowire is not reached, since the interactions between layers is limited by the Cu separation. On the other hand, Fe segments 30 nm in length have exhibited a vortex configuration, with around 60% of the magnetization pointing parallel to the wires' long axis, which is equivalent to an isolated Fe nanodisc. By increasing the Fe segment length, a magnetic reversal occurred through the nucleation and propagation of a V-DW from the extremities of each segment, similar to what happens in a long cylindrical Fe nanowire. The particular case of the Fe/Cu bilayered nanowires with Fe segments 20 nm in length revealed a magnetization oriented in opposite directions, forming a synthetic antiferromagnetic system with coercivity and remanence values close to zero.

scholarly journals Role of Zn And Polyaniline In Magnetic Nanocomposites And Enhanced Arsenic Adsorption Capacity In Wastewater

2021 ◽  
Author(s):  
Tran Minh Thi ◽  
Nguyen Mau Lam ◽  
Do Khanh Tung ◽  
Nguyen Manh Nghia ◽  
Duong Quoc Van ◽  
...  
Keyword(s):  
Grain Size ◽  
Adsorption Capacity ◽  
Relative Pressure ◽  
Arsenic Adsorption ◽  
Saturation Magnetic Moment ◽  
Structure Of Nanoparticles ◽  
Bet Method ◽  
Xrd Patterns ◽  
20 Nm

Abstract Polyaniline/Fe0.90Zn0.10Fe2O4 (PANI/Zn0.10Fe2.90O4) nanocomposites were synthesized by a chemical method and an onsite polymerization method. XRD patterns showed that the Zn0.10Fe2.90O4 grain size about 12 nm, while TEM image showed grain size from 10 to 20 nm. The results of Raman spectra and DTA analyses showed that PANI participated in part of the PANI/Zn0.10Fe2.90O4 nanocomposite samples. The grain size of PANI/Zn0.10Fe2.90O4 samples measured by SEM was about 35–50 nm. These results demonstrated the shell–core structures of the nanocomposite material. The magnetization measurements at room temperature showed that in 1250 Oe magnetic field, the saturation magnetic moment of PANI/Zn0.10Fe2.90O4 samples decreased from 71.2 to 42.3 emu/g when the PANI concentration increased from 0 % to 15 %. The surface area and porous structure of nanoparticles were investigated by the BET method at 77 K and a relative pressure P/P0 of about 1. The arsenic adsorption capacity of the PANI/Zn0.10Fe2.90O4 sample with the PANI concentration of 5 % was better than that of Fe3O4 and Zn0.10Fe2.90O4 in a solution of pH 7. In the solution with pH P14, the arsenic adsorption of magnetic nanoparticles was insignificant. Due to substitution of Fe ions by Zn transition metal and coating polyaniline, these materials could be reabsorbed and reused.

Random and exchange anisotropy in consolidated nanostructured Fe and Ni: Role of grain size and trace oxides on the magnetic properties

1998 ◽  
Vol 57 (5) ◽  
pp. 2915-2924 ◽  
Author(s):  
Jörg F. Löffler ◽  
Jürg P. Meier ◽  
Bernard Doudin ◽  
Jean-Philippe Ansermet ◽  
Werner Wagner
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Exchange Anisotropy

Strength and Ductility in Electrodeposited Nanocrystalline Nickel

2009 ◽  
Vol 633-634 ◽  
pp. 411-420 ◽  
Author(s):  
Heather W. Yang ◽  
Farghalli A. Mohamed
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Annealing Treatment ◽  
Average Grain Size ◽  
Annealing Twins ◽  
Grain Distribution ◽  
Small Grains ◽  
20 Nm ◽  
Strength And Ductility

Electrodeposited nanocrystalline (nc) Ni having an average grain size of 20 nm was annealed at 443 K for different holding times. An examination of the microstructure following annealing showed three important features. First, all annealed samples exhibited abnormal grain growth, which was manifested by the presence of large grains that were surrounded by regions of small grains (bimodal grain distributions). Second, annealing twins existed in the large grains of the samples that showed a bimodal grain distribution. Third, by estimating the density of annealing twin, it was found that annealing nc-Ni at 443 K resulted in a maximum twin density after 5h. Following annealing treatment, specimens with different volume fractions of twins were tested under uniaxial tension at 393 K and a strain rate of 10-4 s-1. The results showed that both strength and ductility in nc-Ni attained maximum values after annealing for 5h. The role of both bimodal grain distributions and annealing twins in enhancing ductility and strength was discussed.

scholarly journals Role of superoxide anion radicals in ethanol metabolism by blood monocyte-derived human macrophages.

1989 ◽  
Vol 169 (3) ◽  
pp. 755-763 ◽  
Author(s):  
S N Wickramasinghe
Keyword(s):  
Superoxide Anion ◽  
Ethanol Oxidation ◽  
Fold Increase ◽  
Ethanol Metabolism ◽  
Blood Monocyte ◽  
Human Macrophages ◽  
20 Nm ◽  
Superoxide Anion Radicals ◽  
Anion Radicals

The effects of a number of additives on the rate of conversion of ethanol (1 mg/ml; 21.7 mM) to acetate by monolayers of blood monocyte-derived human macrophages were investigated. The additives studied were superoxide dismutase (SOD; 1,500 U/ml), catalase (1,500 U/ml), tetrahydrofurane (20 mM), and PMA (20 nM), either singly or in various combinations. SOD, catalase, SOD plus catalase, tetrahydrofurane, and tetrahydrofurane plus SOD inhibited ethanol oxidation by 49.2, 12.1, 52.9, 60.4, and 66.8%, respectively. PMA caused a 4.0-8.3-fold increase in the rate of ethanol metabolism and this increase was completely suppressed in the presence of SOD. The data indicate that a substantial proportion of the ethanol metabolism by both unstimulated and PMA-stimulated blood monocyte-derived macrophages was dependent on the generation of superoxide anion radicals.

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