scholarly journals Fabrication and characterization of magnetic FePt nanoparticles prepared by extraction–pyrolysis method

Chemija ◽  
2018 ◽  
Vol 29 (2) ◽  
Author(s):  
V. Serga ◽  
M. Maiorov ◽  
A. Cvetkovs ◽  
A. Krumina ◽  
A. I. Popov
Keyword(s):  
Magnetic Measurements ◽  
Iron Chloride ◽  
Molar Ratio ◽  
Disperse Powder ◽  
Fept Nanoparticles ◽  
Fept Alloy ◽  
Extraction Pyrolysis ◽  
Pyrolysis Method ◽  
The Face ◽  
Face Centered

In the present work, possibilities of the extraction–pyrolysis method (EPM) to produce FePt nanoparticles with the face-centered tetragonal (fct) phase were studied. A mixture of fine-disperse powder of carbonyl iron and n-trioctylammonium hexachloroplatinate [(С8Н17)3NH]2PtCl6 solution in toluene, preliminary produced by the solvent extraction method, is used as a precursor. Precursors with a different molar ratio of metals were used. The performed investigations show that as a result of pyrolysis in the air (Tpyr = 600°C, tanneal = 30 min), a FePt alloy with the fct phase is produced. Moreover, such phases as FePt3 and/or Fe3Pt with the cubic structure may be also present in the final products. The phase composition of the produced samples depends on the Fe:Pt molar ratio in the precursor. An increase of the fct phase part with the growth of the iron content from 40 to 60 mol% is observed. Also, with the Fe80%Pt20% molar ratio of the metals in the precursor, only the ordered fct phase along with a small amount of hematite and iron chloride exists in the produced sample. Magnetic measurements confirm the fct-FePt phase formation in all produced samples and evidence that the coercivity exceeds the value (3 kOe) at the 50 mol% Fe concentration in the precursor and significantly decreases with increasing the Fe concentration to 80 mol%.

Formation of Ferromagnetic FePt Nanoparticles by Ion Implantation

2001 ◽  
Vol 704 ◽  
Author(s):  
C. W. White ◽  
S. P. Withrow ◽  
J. D. Budai ◽  
L. A. Boatner ◽  
K. D. Sorge ◽  
...  
Keyword(s):  
Particle Size ◽  
Ion Implantation ◽  
Single Crystal ◽  
Fept Nanoparticles ◽  
Fept Alloy ◽  
The Face ◽  
Face Centered

AbstractOriented ferromagnetic FePt nanoparticles with the face-centered tetragonal L10 structure were produced in Al2O3 single crystal hosts by ion implantation and annealing. Both the orientation and particle-size of the FePt particles depend strongly on the implantation conditions. The magnetic coercivities are extremely high, reaching values in excess of 20 kOe for Pt concentrations of ∼45% in the FePt alloy. Ferromagnetic FePt nanoparticles were also produced in amorphous SiO2 by ion implantation and annealing.

Novel Nanohybrids Derived from the Attachment of FePt Nanoparticles on Carbon Nanotubes

2008 ◽  
Vol 8 (11) ◽  
pp. 5942-5951 ◽  
Author(s):  
Theodoros Tsoufis ◽  
Aphrodite Tomou ◽  
Dimitrios Gournis ◽  
Alexios P. Douvalis ◽  
Ioannis Panagiotopoulos ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Carbon Nanotubes ◽  
Particle Size ◽  
Fept Nanoparticles ◽  
Face Centered Cubic ◽  
Magnetization Measurements ◽  
Hybrid Sample ◽  
The Face ◽  
Face Centered ◽  
Mwcnts Surface

Multiwalled carbon nanotubes (MWCNTs) were used as nanotemplates for the dispersion and stabilization of FePt nanoparticles (NPs). Pre-formed capped FePt NPs were connected to the MWCNTs external surface via covalent binding through organic linkers. Free FePt NPs and MWCNTs-FePt hybrids were annealed in vacuum at 700 °C in order to achieve the L10 ordering of the FePt phase. Both as prepared and annealed samples were characterized and studied using a combination of experimental techniques, such as Raman and Mössbauer spectroscopies, powder X-ray Diffraction (XRD), magnetization and transmittion electron microscopy (TEM) measurements. TEM measurements of the hybrid sample before annealing show that a fine dispersion of NPs along the MWCNTs surface is achieved, while a certain amount of free particles attached to each other in well connected dense assemblies of periodical or non-periodical particle arrangements is also observed. XRD measurements reveal that the FePt phase has the face-centered cubic (fcc) disordered crystal structure in the as prepared samples, which is transformed to the face-centered tetragonal (fct) L10 ordered crystal structure after annealing. An increase in the average particle size is observed after annealing, which is higher for the free NPs sample. Superparamagnetic phenomena due to the small FePt particle size are observed in the Mössbauer spectra of the as prepared samples. Mössbauer and magnetization measurements of the MWCNTs-FePt hybrids sample reveal that the part of the FePt particles attached to the MWCNTs surface shows superparamagnetic phenomena at RT even after the annealing process. The hard magnetic L10 phase characteristics are evident in the magnetization measurements of both samples after annealing, with the coercivity of the hybrid sample over-scaling that of the free NPs sample by a factor of 1.25.

Investigation on Structure Transition of Fullerene During Mechanical Alloying and Subsequent Treatments

2000 ◽  
Vol 15 (7) ◽  
pp. 1528-1537
Author(s):  
Z. G. Liu ◽  
H. Ohi ◽  
K. Masuyama ◽  
K. Tsuchiya ◽  
M. Umemoto
Keyword(s):  
Mechanical Milling ◽  
Polymerization Process ◽  
Molar Ratio ◽  
Face Centered Cubic ◽  
Scanning Calorimetry ◽  
Structure Transition ◽  
Characterization Methods ◽  
Fullerene Soot ◽  
The Face ◽  
Face Centered

Mechanical milling of fullerene (soot containing C60/C70 fullerenes in a 8:2 molar ratio) was investigated through various characterization methods. It was found that mechanical milling would not destroy the molecular structure of fullerene C60 (C70), while the long-range order of the face-centered-cubic crystalline structure was easily modified and transformed into amorphous phase, a mixture of fullerene C60 (C70) polymers and monomers. Differential scanning calorimetry analysis revealed a recovery of polymers to pristine fullerene molecules at 678 K, which is much higher than the reported depolymerization temperature of fullerene polymers induced by photo irradiation and by high-pressure–temperature processes. It is suggested that the contaminated Fe acts as a catalyst in the polymerization process.

scholarly journals Synthesis of Bimetallic PdAg Nanoparticles and Their Electrocatalytic Activity toward Ethanol

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Fahui Gao ◽  
Yanru Yin ◽  
Zhengshuai Cao ◽  
Hongliang Li ◽  
Peizhi Guo
Keyword(s):  
Electrocatalytic Activity ◽  
Bimetallic Nanoparticles ◽  
Molar Ratio ◽  
Face Centered Cubic ◽  
Ethanol Electrooxidation ◽  
Uniform Size ◽  
Catalytic Current ◽  
The Face ◽  
Alloy Nanostructures ◽  
Face Centered

Palladium-based bimetallic nanoparticles (NPs) have been studied as important electrocatalysts for energy conversion due to their high electrocatalytic performance and the less usage of the noble metal. Herein, well-dispersed PdAg NPs with uniform size were prepared via oil bath accompanied with the hydrothermal method. The variation of the Ag content in PdAg NPs changed the lattice constant of the face-centered cubic alloy nanostructures continuously. The Pd/Ag molar ratio in the PdAg alloy NPs affected their size and catalytic activity toward ethanol electrooxidation. Experimental data showed that PdAg NPs with less Ag content exhibited better electrocatalytic activity and durability than pure Pd NPs owing to both the small size and the synergistic effect. PdAg-acac-4 with the Pd/Ag molar ratio of 4 : 1 in the start system possessed the highest catalytic current density of 2246 mA/mg for the electrooxidation of ethanol. The differences in the morphology and electrocatalytic activity of the as-made PdAg NPs have been discussed and analyzed.

scholarly journals Theoretical confirmation of Ga-stabilized anti-ferromagnetism in plutonium metal

2014 ◽  
Vol 1683 ◽  
Author(s):  
Per Söderlind ◽  
Alex Landa
Keyword(s):  
Density Functional ◽  
Magnetic Measurements ◽  
Theory Model ◽  
Face Centered Cubic ◽  
Mechanical Instability ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
The Face ◽  
Face Centered ◽  
Plutonium Metal

ABSTRACTThe density-functional-theory model for plutonium metal is shown to be consistent with recent magnetic measurements that suggest anti-ferromagnetism in Pu-Ga alloys at low temperatures. The theoretical model predicts a stabilization of the face-centered-cubic (fcc, δ) form of plutonium in an anti-ferromagnetic configuration when alloyed with gallium. The ordered magnetic phase occurs because Ga removes the mechanical instability that exists for unalloyed δ-Pu. The cause of the Ga-induced stabilization is a combination of a lowering of the band (kinetic) and electrostatic (Coulomb) energies for the cubic relative to the tetragonal phase.

A study of interface sliding at F.C.C.-B.C.C. boundaries in a Cu-Zn alloy

1978 ◽  
Vol 36 (1) ◽  
pp. 422-423
Author(s):  
F. Monchoux ◽  
A. Rocher ◽  
J.L. Martin
Keyword(s):  
Face Centered Cubic ◽  
Creep Tests ◽  
High Voltage Electron Microscopy ◽  
Diffusion Treatment ◽  
Voltage Electron ◽  
The Face ◽  
Face Centered ◽  
Interface Sliding ◽  
Zn Alloy ◽  
Made In

Interphase sliding is an important phenomenon of high temperature plasticity. In order to study the microstructural changes associated with it, as well as its influence on the strain rate dependence on stress and temperature, plane boundaries were obtained by welding together two polycrystals of Cu-Zn alloys having the face centered cubic and body centered cubic structures respectively following the procedure described in (1). These specimens were then deformed in shear along the interface on a creep machine (2) at the same temperature as that of the diffusion treatment so as to avoid any precipitation. The present paper reports observations by conventional and high voltage electron microscopy of the microstructure of both phases, in the vicinity of the phase boundary, after different creep tests corresponding to various deformation conditions.Foils were cut by spark machining out of the bulk samples, 0.2 mm thick. They were then electropolished down to 0.1 mm, after which a hole with thin edges was made in an area including the boundary

scholarly journals Structural and Magnetic Properties of Potassium-Doped 2,3-DiMethylnaphthalene

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 608
Author(s):  
Xiao-Lin Wu ◽  
Ren-Shu Wang ◽  
Hui Yang ◽  
Jie Zhang ◽  
Ming-An Fu ◽  
...  
Keyword(s):  
Benzene Ring ◽  
Organic Molecules ◽  
Magnetic Measurements ◽  
Ring Structure ◽  
Molar Ratio ◽  
First Principles Calculations ◽  
Paramagnetic Behavior ◽  
Polycyclic Aromatic ◽  
Metal Doped ◽  
Derivatives Of

The development of potential magnetic materials in metal-doped polycyclic aromatic hydrocarbons has been a research hotspot in recent years. Here we have successfully synthesized stable potassium-doped 2,3-dimethylnaphthalene samples. The combination of first-principles calculations and XRD results identifies that doping of potassium into 2,3-dimethylnaphthalene forms a monoclinic structure with a molar ratio of 1:2 between potassium and molecule. The red shifts in the Raman spectra indicate that potassium 4s electrons are transferred to the organic molecules. The magnetic measurements show that the doped materials exhibit a temperature-independent magnetization in the temperature region of 1.8–300 K, which is consistent with the Pauli paramagnetic behavior. This is distinct from the diamagnetism of pristine material. Compared to the previous focus on benzene ring structure, our study of aromatic hydrocarbon derivatives of benzene ring opens a new route for the development of this field.

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