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.

Sn hyperfine field distributions in the Heusler alloys XMnSn and X2MnSn

1981 ◽  
Vol 59 (11) ◽  
pp. 1577-1584 ◽  
Author(s):  
R. A. Dunlap ◽  
R. H. March ◽  
G. Stroink
Keyword(s):  
Hyperfine Field ◽  
Fourier Expansion ◽  
Heusler Alloys ◽  
Expansion Method ◽  
Wide Distribution ◽  
Ordered Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Field Distributions ◽  
Hyperfine Field Distributions

The 119Sn hyperfine field in the Heusler alloys Ir1.07Mn1.07Sn0.86, PtMnSn, Ni2MnSn, Co2MnSn, and Pd2MnSn has been measured using the Mössbauer effect. Hyperfine field distributions were obtained from the Mössbauer spectra via the Fourier expansion method of Window. The spectra of Ni2MnSn, Co2MnSn, and Pd2MnSn showed a well-defined value of the hyperfine field. This indicates a well-ordered structure and is consistent with previous neutron diffraction and NMR measurements on these alloys. The Ir1.07Mn1.07Sn0.86 and PtMnSn spectra, on the other hand, showed a wide distribution of fields, indicating a considerable amount of disorder. The extent and type of disorder, as indicated by X-ray diffraction measurements, are also considered.

Effect of Cooling Rate on the Structure of Rapidly Cooled Fe75Si15 B10

1983 ◽  
Vol 28 ◽  
Author(s):  
John L. Walter ◽  
Ami E. Berkowitz
Keyword(s):  
Cooling Rate ◽  
Melt Spinning ◽  
Structural Characteristics ◽  
Rapid Quenching ◽  
Metal Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spark Erosion ◽  
Water Atomization ◽  
Solidification Of Metal

Solidification of metal alloys by rapid quenching can result in the formation of amorphous or microcrystalline solids, or materials with improved microstructural homogeneity, all with the view of forming new phases or obtaining improved properties. Some alloys may be cooled at high rates to achieve “microcrystallinity” but cannot be cooled rapidly enough to become amorphous. Other alloys may achieve both conditions depending on the cooling rate. We have examined the effects of cooling rate on the structure of one alloy that can, depending on the cooling rate, be made partially or completely amorphous. The alloy is Fe75Si15B10 (atom percent) which was formed as ribbon by melt spinning and as powder by spark erosion in dielectrics of different cooling characteristics and by gas-water atomization. The structural characteristics were determined by x-ray diffraction, measurements of magnetic properties and by optical and scanning electron microscopy.

scholarly journals Neutron diffraction and ab initio studies on the fully compensated ferrimagnetic characteristics of Mn2V1-xCoxGa Heusler alloys

2021 ◽  
Author(s):  
Midhunlal P V ◽  
Venkatesh Chandragiri ◽  
J Arout Chelvane ◽  
P D Babu ◽  
Harish Kumar Narayanan
Keyword(s):  
Neutron Diffraction ◽  
Ab Initio ◽  
Structural Transition ◽  
Magnetic Measurements ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atom Pairs ◽  
Co Concentration

Abstract Neutron diffraction and ab initio studies were carried out on Mn2V1-xCoxGa (x = 0, 0.25, 0.5, 0.75, 1) Heusler alloys which exhibits high TC fully compensated ferrimagnetic characteristics for x = 0.5. A combined analysis of neutron diffraction and ab initio calculations revealed the crystal structure and magnetic configuration which could not be determined from the X-ray diffraction and magnetic measurements. As reported earlier, Rietveld refinement of neutron diffraction data confirmed L21 structure for Mn2VGa and Xa structure for Mn2CoGa. The alloys with x = 0.25 and 0.5 possess L21 structure with Mn(C)-Co disorder. As the Co concentration reaches 0.75, a structural transition has been observed from disordered L21 to disordered X a. Detailed ab initio studies also confirmed this structural transition. The reason for the magnetic moment compensation in Mn2(V1-xCox)Ga was identified to be different from that of the earlier reported fully compensated ferrimagnet (MnCo)VGa. With the help of neutron diffraction and ab initio studies, it is identified that the disordered L21 structure with antiparallel coupling between the ferromagnetically aligned magnetic moments of (Mn(A)-Mn(C)) and (V-Co) atom pairs enables the compensation in Mn2V1-xCoxGa.

Logarithmic Relaxation of Resistance in Time of Annealed and Plastically Deformed Au80Fe20

2000 ◽  
Vol 634 ◽  
Author(s):  
P. Allia ◽  
M. Baricco ◽  
E. Bosco ◽  
M. Coisson ◽  
D. Falletti ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
Melt Spinning ◽  
Magnetic Measurements ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Rapidly Solidified

ABSTRACTRapidly solidified Au80Fe20 ribbons were prepared either by melt spinning or by solidstate quenching of a homogenised master alloy. The as-quenched sample displays a paramagnetic behavior indicating a perfect solid solution of Fe in the Au matrix. Subsequent anneals have been performed to induce the precipitation of Fe particles. X-ray diffraction technique have been exploited to determine the alloy microstructure. The structural stability have been studied by measuring electrical properties in isothermal and tempering condition. The variation of magnetisation and electrical resistance have been measured after submitting the samples to plastic deformation. A logarithmic relaxation of the electrical resistance is observed in all studied samples after deformation. Magnetic hysteresis loops have been measured in as-quenched and annealed samples at different temperatures. X-ray diffraction and magnetic measurements indicate that thermal treatments have been successful in inducing the precipitation of both bcc and fcc Fe clusters.

Mechanically Driven Dissolution of Sn in Near-Equiatomic Bcc FeCo

2012 ◽  
Vol 194 ◽  
pp. 187-193 ◽  
Author(s):  
J.M. Loureiro ◽  
Benilde F.O. Costa ◽  
Gerard Le Caër ◽  
Bernard Malaman
Keyword(s):  
Magnetic Field ◽  
Solid Solutions ◽  
Room Temperature ◽  
Hyperfine Magnetic Field ◽  
Ternary Alloys ◽  
119Sn Mössbauer Spectroscopy ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Powder Mixtures ◽  
X Ray

Ternary alloys, (Fe50−x/2Co50−x/2)Snx(x ≤ 33 at.%), are prepared by mechanical alloying from powder mixtures of the three elements. As-milled alloys are studied by X-ray diffraction and 57Fe and 119Sn Mössbauer spectroscopy. The solubility of Sn in near-equiatomic bcc FeCo is increased from ~0.5 at. % at equilibrium to ~20 at.% in the used milling conditions. The average 119Sn hyperfine magnetic field at room temperature is larger, for any x, than the corresponding fields in mechanically alloyed Fe-Sn solid solutions.

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.

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.

Microstructure Evolution and Mossbauer Spectroscopy Research of Nanostructured Ni3 Fe Intermetallic

2021 ◽  
Vol 32 ◽  
pp. 1-13
Author(s):  
Amel Kaibi ◽  
Abderrahim Guittoum ◽  
Nassim Souami ◽  
Mohamed Kechouane
Keyword(s):  
Magnetic Field ◽  
Mössbauer Spectroscopy ◽  
Mössbauer Spectra ◽  
Milling Time ◽  
Mossbauer Spectroscopy ◽  
Hyperfine Magnetic Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Mößbauer Spectroscopy

Nanocrystalline Ni75Fe25 (Ni3Fe) powders were prepared by mechanical alloying process using a vario-planetary high-energy ball mill. The intermetallic Ni3Fe formation and different physical properties were investigated, as a function of milling time, t, (in the range 6 to 96 h range), using X-Ray Diffraction (XRD) and Mössbauer Spectroscopy techniques. X-ray diffraction were performed on the samples to understand the structural characteristics and get information about elements and phases present in the powder after different time of milling. The refinement of XRD spectra revealed the complete formation of fcc Ni (Fe) disordered solid solution after 24 h of milling time, the Fe and Ni elemental distributions are closely correlated. With increasing the milling time, the lattice parameter increases and the grains size decreases. The Mössbauer experiments were performed on the powders in order to follow the formation of Ni3Fe compound as a function of milling time. From the adjustment of Mössbauer spectra, we extracted the hyperfine parameters. The evolution of hyperfine magnetic field shows that the magnetic disordered Ni3Fe phase starts to form from 6 h of milling time and grow in intensity with milling time. For the milling time more than 24 h, only the Ni3Fe disordered phase is present with a mean hyperfine magnetic field of about 29.5 T. The interpretation of the Mossbauer spectra confirmed the results obtained by XRD.

Influence of Alloying Additions on Enhancement of Soft Magnetic Properties Effect and Crystallization in FeXSiB (X=Cu, V, Co, Zr, Nb) Amorphous Alloys

2007 ◽  
Vol 130 ◽  
pp. 171-174 ◽  
Author(s):  
Z. Stokłosa ◽  
G. Badura ◽  
P. Kwapuliński ◽  
Józef Rasek ◽  
G. Haneczok ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Crystallization Process ◽  
Annealing Temperature ◽  
Magnetic Measurements ◽  
X Ray Diffraction ◽  
Soft Magnetic ◽  
X Ray ◽  
Second Stage ◽  
Transmission Electron

The crystallization and optimization of magnetic properties effects in FeXSiB (X=Cu, V, Co, Zr, Nb) amorphous alloys were studied by applying X-ray diffraction methods, high resolution transmission electron microscopy (HRTEM), resistometric and magnetic measurements. The temperatures of the first and the second stage of crystallization, the 1h optimization annealing temperature and the Curie temperature were determined for different amorphous alloys. Activation energies of crystallization process were obtained by applying the Kissinger method. The influence of alloy additions on optimization effect and crystallization processes was carefully examined.

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