L12 Ordering in Disordered NiAIFe Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
A.R Yavari ◽  
M.D. Baro ◽  
G. Fillion ◽  
S. Surinach ◽  
S. Gialanella ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Magnetic Moment ◽  
Cold Working ◽  
Magnetic Measurements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fe Alloys

ABSTRACT:Ordering of the disordered state (obtained by cold-working or by meltspinning) of L12 type Ni,AI,Fe alloys has been monitored by calorimetric, magnetic and X-ray diffraction measurements .It is found that the magnetic moment per atom of the Ni,Al,Fe alloys in the γ-disordered state is about half of that of the LI2 -γ'state. Magnetic measurements such as ours constitute a new tool for studyingthe γ→γ' transition below the Curie temperature.

scholarly journals Влияние Cr и Ni на формирование фаз в механосинтезированном нанокомпозите на основе Fe-=SUB=-75-=/SUB=-C-=SUB=-25-=/SUB=-

2020 ◽  
Vol 90 (5) ◽  
pp. 787
Author(s):  
А.А. Чулкина ◽  
А.И. Ульянов ◽  
В.А. Волков ◽  
А.Л. Ульянов ◽  
А.В. Загайнов
Keyword(s):  
Curie Temperature ◽  
Amorphous Phase ◽  
Annealing Temperature ◽  
Magnetic Measurements ◽  
Nickel Content ◽  
X Ray Diffraction ◽  
Mechanical Synthesis ◽  
X Ray ◽  
Higher Temperature ◽  
Two Phases

X-ray diffraction, Mossbauer spectroscopy, and magnetic measurements have been used to study the phase formation and doping during mechanical synthesis (MS) and subsequent annealing of the alloy (Fe0.80Cr0.05Ni0.15)75C25. It has been shown that, after MS, the nanocomposite contains mainly two phases – an amorphous phase and cementite A. During annealing, as a result of crystallization of the amorphous phase, cementite B is formed, in which contains more nickel than in the mechanically synthesized cementite A. As the annealing temperature increases, austenite, which is inhomogeneous in nickel content, is formed. The Curie temperature of this austenite reaches 500 °C. It has been determined that cementite in the mechanosynthesized nanocomposite (Fe,Cr,Ni)75C25 has a higher temperature stabilitythan that in a MS composite (Fe,Ni)75C25.

Ferromagnetic Ordering in the Thallide EuPdTl2

2006 ◽  
Vol 61 (2) ◽  
pp. 159-163 ◽  
Author(s):  
Rainer Kraft ◽  
Sudhindra Rayaprol ◽  
C. Peter Sebastian ◽  
Rainer Pöttgen
Keyword(s):  
Curie Temperature ◽  
Single Crystals ◽  
Magnetic Moment ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Zintl Phase ◽  
X Ray ◽  
Divalent Europium ◽  
Ferromagnetic Ordering

AbstractThe new thallide EuPdTl2, synthesized from the elements in a sealed tantalum tube in a highfrequency furnace, was investigated by X-ray diffraction on powders and single crystals: MgCuAl2 type, Cmcm, Z = 4, a = 446.6(1), b = 1076.7(2), c = 812.0(2) pm, wR2 = 0.0632, 336 F2 values, 16 variables. The structure can be considered as an orthorhombically distorted, palladium-filled variant of the binary Zintl phase EuTl2. The palladium and thallium atoms build up a three-dimensional [PdTl2] polyanion with significant Pd-Tl (286 - 287 pm) and Tl-Tl (323 - 329 pm) interactions. The europium atoms fill distorted hexagonal channels of the [PdTl2] polyanion. Susceptibility measurements show a magnetic moment of 7.46(5) μB/Eu atom, indicative of divalent europium. EuPdTl2 is a soft ferromagnet with a Curie temperature of TC = 12.5(5) K.

Synthesis of Ferromagnetic Germanides in 40Ge/60Mn Films: Magnetic and Structural Properties

2014 ◽  
Vol 215 ◽  
pp. 167-172
Author(s):  
Victor G. Myagkov ◽  
A.A. Matsunin ◽  
Y.L. Mikhlin ◽  
Victor S. Zhigalov ◽  
Liudmila E. Bykova ◽  
...  
Keyword(s):  
Solid State ◽  
Curie Temperature ◽  
Photoelectron Spectroscopy ◽  
Magnetic Measurements ◽  
Atomic Ratio ◽  
Photoelectron Spectra ◽  
Solid State Reactions ◽  
Ferromagnetic Phase ◽  
X Ray Diffraction ◽  
X Ray

Solid-state reactions between Ge and Mn films are systematically examined using X-ray diffraction, photoelectron spectroscopy and magnetic measurements. The films have a nominal atomic ratio Ge:Mn = 40:60 and are investigated at temperatures from 50 to 500 °С. It is established that after annealing at ~120 °С, the ferromagnetic Mn5Ge3 phase is the first phase to form at the 40Ge/60Mn interface. Increasing the annealing temperature to 500 °С leads to the formation of the ferromagnetic phase with a Curie temperature TC ~ 360 K and magnetization MS ~ 140-200 emu/cc at room temperature. Analysis of X-ray diffraction patterns and the photoelectron spectra suggests that the increased Curie temperature and magnetization are related to the migration of C and O atoms into the Mn5Ge3 lattice and the formation of the Nowotny phase Mn5Ge3СxOy. The initiation temperature (~120 °С) of the Mn5Ge3 phase is the same both for solid-state reactions in Ge/Mn films, as well as for phase separation in GexMn1-x diluted semiconductors. We conclude that the synthesis of the Mn5Ge3 phase is the moving force for the spinodal decomposition of the GexMn1-x diluted semiconductors.

Formation of the Hipernik Alloy by Mechanical Alloying

2011 ◽  
Vol 672 ◽  
pp. 68-71
Author(s):  
Ionel Chicinaş ◽  
Viorel Pop ◽  
Florin Popa ◽  
Virgiliu Călin Prică ◽  
Traian Florin Marinca ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Magnetic Measurements ◽  
Magnetic Behaviour ◽  
Alloy Formation ◽  
X Ray Diffraction ◽  
Chemical Homogeneity ◽  
X Ray ◽  
Powder Mass ◽  
The Mean ◽  
Fe Alloys

The Hipernik alloy (50Ni50Fe wt. %) was obtained by mechanical alloying. The milling was performed in argon atmosphere, with a ball/powder mass ration of 8:1 for times ranging from 2 up to 20h. The alloy formation was studied by X-ray diffraction. The obtained structure is face cantered cubic, indicating the extension of the γ domain for the Ni-Fe alloys by mechanical alloying. The mean crystallite size was calculated with the Williamson – Hall method. Using scanning electron microscopy (SEM) the morphology and the chemical homogeneity of the powders was analysed. The technological properties of the powders as particle size distribution and flowability are determined as a function of the milling time. The magnetic behaviour of the samples was studied by magnetic measurements under high magnetic fields.

Ternary Antimonides RE4T7Sb6 (RE=Gd–Lu; T =Ru, Rh) with Cubic U4Re7Si6-type Structure

2013 ◽  
Vol 68 (9) ◽  
pp. 971-978 ◽  
Author(s):  
Inga Schellenberg ◽  
Ute Ch. Rodewald ◽  
Christian Schwickert ◽  
Matthias Eul ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Susceptibility ◽  
Single Crystal ◽  
Magnetic Moment ◽  
Induction Furnace ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Arc Melting ◽  
Intermediate Valent

The ternary antimonides RE4T7Sb6 (RE=Gd-Lu; T =Ru, Rh) have been synthesized from the elements by arc-melting and subsequent annealing in an induction furnace. The samples have been characterized by powder X-ray diffraction. Four structures were refined on the basis of single-crystal X-ray diffractometer data: U4Re7Si6 type, space group Im3m with a=862.9(2) pm, wR2=0.0296, 163 F2 values for Er4Ru7Sb6; a=864.1(1) pm, wR2=0.1423, 153 F2 values for Yb4Ru7Sb6; a=872.0(2) pm, wR2=0.0427, 172 F2 values for Tb4Rh7Sb6; and a=868.0(2) pm, wR2=0.0529, 154 F2 values for Er4Rh7Sb6, with 10 variables per refinement. The structures have T1@Sb6 octahedra and slightly distorted RE@T26Sb6 cuboctahedra as building units. The distorted cuboctahedra are condensed via all trapezoidal faces, and this network leaves octahedral voids for the T1 atoms. The ruthenium-based series of compounds was studied by temperature-dependent magnetic susceptibility measurements. Lu4Ru7Sb6 is Pauli-paramagnetic. The antimonides RE4Ru7Sb6 with RE=Dy, Ho, Er, and Tm show Curie-Weiss paramagnetism. Antiferromagnetic ordering occurs at 10.0(5), 5.1(5) and 4.0(5) K for Dy4Ru7Sb6, Ho4Ru7Sb6 and Er4Ru7Sb6, respectively, while Tm4Ru7Sb6 remains paramagnetic. Yb4Ru7Sb6 is an intermediate-valent compound with a reduced magnetic moment of 3.71(1) μB per Yb as compared to 4.54 μB for a free Yb3+ ion

scholarly journals Dissimilatory Iron-Reducing Microorganisms Are Present and Active in the Sediments of the Doce River and Tributaries Impacted by Iron Mine Tailings from the Collapsed Fundão Dam (Mariana, MG, Brazil)

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 244
Author(s):  
Carolina N. Keim ◽  
Jilder D. P. Serna ◽  
Daniel Acosta-Avalos ◽  
Reiner Neumann ◽  
Alex S. Silva ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
Magnetic Measurements ◽  
Culture Media ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ferric Oxyhydroxide ◽  
Transmission Electron ◽  
Iron Mine ◽  
Organic Matter Oxidation ◽  
Doce River

On 5 November 2015, a large tailing deposit failed in Brazil, releasing an estimated 32.6 to 62 million m3 of iron mining tailings into the environment. Tailings from the Fundão Dam flowed down through the Gualaxo do Norte and Carmo riverbeds and floodplains and reached the Doce River. Since then, bottom sediments have become enriched in Fe(III) oxyhydroxides. Dissimilatory iron-reducing microorganisms (DIRMs) are anaerobes able to couple organic matter oxidation to Fe(III) reduction, producing CO2 and Fe(II), which can precipitate as magnetite (FeO·Fe2O3) and other Fe(II) minerals. In this work, we investigated the presence of DIRMs in affected and non-affected bottom sediments of the Gualaxo do Norte and Doce Rivers. The increase in Fe(II) concentrations in culture media over time indicated the presence of Fe(III)-reducing microorganisms in all sediments tested, which could reduce Fe(III) from both tailings and amorphous ferric oxyhydroxide. Half of our enrichment cultures converted amorphous Fe(III) oxyhydroxide into magnetite, which was characterized by X-ray diffraction, transmission electron microscopy, and magnetic measurements. The conversion of solid Fe(III) phases to soluble Fe(II) and/or magnetite is characteristic of DIRM cultures. The presence of DIRMs in the sediments of the Doce River and tributaries points to the possibility of reductive dissolution of goethite (α-FeOOH) and/or hematite (α-Fe2O3) from sediments, along with the consumption of organics, release of trace elements, and impairment of water quality.

Influence of Severe Plastic Deformation on Physicomechanical Properties of Ti-40 mas % Nb Alloy

2016 ◽  
Vol 685 ◽  
pp. 525-529
Author(s):  
Zhanna G. Kovalevskaya ◽  
Margarita A. Khimich ◽  
Andrey V. Belyakov ◽  
Ivan A. Shulepov
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Cold Working ◽  
Young Modulus ◽  
Physicomechanical Properties ◽  
X Ray Diffraction ◽  
Refined Grains ◽  
X Ray ◽  
Initial Alloy ◽  
Composition Structure

The changes of the phase composition, structure and physicomechanical properties of Ti‑40 mas % Nb after severe plastic deformation are investigated in this paper. By the methods of microstructural, X-ray diffraction analysis and scanning electron microscopy it is determined that phase and structural transformations occur simultaneously in the alloy after severe plastic deformation. The martensitic structure formed after tempering disappears. The inverse α'' → β transformation occurs. The structure consisting of oriented refined grains is formed. The alloy is hardened due to the cold working. The Young modulus is equal to 79 GPa and it is less than that of initial alloy and close to the value obtained after tempering. It is possible that Young modulus is reduced by additional annealing.

scholarly journals Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Structural Evolution ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

Nitroxide radicals appended to phthalonitriles: synthesis, structural characterization and photophysical properties

2021 ◽  
Vol 77 (3) ◽  
pp. 137-143
Author(s):  
Ismail Fidan ◽  
Emel Onal ◽  
Catherine Hirel
Keyword(s):  
Magnetic Measurements ◽  
Photophysical Properties ◽  
Nucleophilic Aromatic Substitution ◽  
Structural Studies ◽  
Aromatic Substitution ◽  
Nitronyl Nitroxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Assisted ◽  
Ft Ir

The syntheses of 4-[4-(4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl-2-yl)phenoxy]phthalonitrile (3, C21H19N4O3) and 4-[4-(4,4,5,5-tetramethyl-2-imidazoline-1-oxyl-2-yl)phenoxy]phthalonitrile (4) were carried out by microwave-assisted nucleophilic aromatic substitution of 4-nitrophthalonitrile (2) by the pre-formed 2-(4-hydroxyphenyl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl (1). Compounds 3 and 4 were characterized unambiguously by a rich array of analyses, such as melting point, FT–IR, MALDI–TOF MS, elemental analysis, UV–Vis, CV, EPR, magnetic measurements and single-crystal X-ray diffraction. Structural studies demonstrate that the C—H...X and C—X...π (X = O and N) interactions in the radical nitronyl nitroxide groups play an important role in the assembly of the crystal structures. Moreover, cyclic voltammetry analyses show that the phthalonitrile substituent retains the redox properties of the Ullman radicals.

Structure, Magnetic Properties and Hyperfine Parameters of Nd-Substituted Ni-Fe-Ga Heusler Alloys

MRS Advances ◽  
2017 ◽  
Vol 2 (25) ◽  
pp. 1341-1346
Author(s):  
Monica Sorescu ◽  
Felicia Tolea ◽  
Mihaela Valeanu ◽  
Mihaela Sofronie
Keyword(s):  
Melt Spinning ◽  
Magnetic Measurements ◽  
Heusler Alloys ◽  
Hyperfine Magnetic Field ◽  
Rapid Quenching ◽  
Linear Least Squares ◽  
X Ray Diffraction ◽  
Hyperfine Parameters ◽  
X Ray ◽  
Field Distributions

ABSTRACTSamples of Ni57-xNdxFe18Ga25 with x=2 and 4 were prepared in ribbon form by rapid quenching via melt spinning route. The samples were analyzed by X-ray diffraction (XRD), magnetic measurements and Mössbauer spectroscopy, both in the as-quenched form and after thermal annealing at 900 oC for 2 min and 400 °C for 2 hours. For x=2 the Nd atoms are completely dissolved in the Ni-Fe-Ga matrix, while for x=4 the additional occurrence of the secondary 2:17 phase could be resolved. These findings were supported by the analysis of hyperfine magnetic field distributions obtained from the non-linear least-squares fitting of the Mössbauer spectra.

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