Magnetic Studies of Ni3Al(Fe) Compounds

1984 ◽  
Vol 39 ◽  
Author(s):  
S. T. Sekula ◽  
H. R. Kerchner ◽  
J. R. Thompson ◽  
Th. Leventouri
Keyword(s):  
Curie Temperature ◽  
Magnetic Measurements ◽  
Lattice Parameter ◽  
Magnetic Studies ◽  
Fe Content ◽  
Magnetization Data ◽  
Ordered Intermetallic ◽  
Material Forming ◽  
Fcc Phase ◽  
Fe Impurities

ABSTRACTSeveral samples of the ordered intermetallic compound with the Ll2 structure and chemical composition NiO.75-xAl0.25-xFe2x (doped with 0.2 at. % B) have been studied over an Fe compositional range 0 ≤ 2x ≤ 0.20. Stoichiometric Ni3Al is known to be a strongly exchange-enhanced-material, forming a giant moment system when Fe impurities are introduced in trace amounts. For the greater Fe concentrations employed in this work, more conventional ferromagnetic systems are obtained. Well below the ferromagnetic Curie temperature Tc the samples exhibit a spontaneous moment in small magnetic fields and at higher fields the isothermal magnetization data show a clear tendency toward saturation. Magnetic investigations using vibrating-sample techniques permitted measurements over the temperature interval from 4.2 K to 800 K in fields up to 5.0 T. The Curie temperature was found to increase from ∼50 K for the Fe-free sample in the series to 410 K for the limiting concentration of 12 at. % Fe in the Ll2 structure. Samples with higher Fe content up to 20 at. % contain a second, disordered fcc phase with Tc ≃ 715 K. Peaks in the temperature dependence of the lattice parameter observed in x-ray studies yield Tc values in reasonable agreement with the magnetic measurements.

The Solid Solutions Gd2Cu2In1–xMgx – Drastic Increase of the Curie Temperature upon In/Mg Substitution

2010 ◽  
Vol 65 (12) ◽  
pp. 1516-1520 ◽  
Author(s):  
Wilfried Hermes ◽  
Falko M. Schappacher ◽  
Rainer Pöttgen
Keyword(s):  
Curie Temperature ◽  
Intermetallic Compounds ◽  
Solid Solutions ◽  
Temperature Increase ◽  
Magnesium Content ◽  
Lattice Parameter ◽  
Weiss Constant ◽  
Drastic Increase ◽  
Complete Set ◽  
Mg Substitution

The Mo2B2Fe-type intermetallic compounds Gd2Cu2In and Gd2Cu2Mg form a complete set of solid solutions Gd2Cu2In1−xMgx. The a lattice parameter, the Weiss constant and the Curie temperature increase with increasing magnesium content in an almost Vegard-like manner, while the c parameter remains almost constant. All members of the solid solutions show ferromagnetism with TCs between 114 and 80 K.

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.

Transmission Electron Microscopy Study of Mod Plzt and Pnzt Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Jhing–Fang Chang ◽  
Chi Kong Kwok ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Curie Temperature ◽  
Dopant Concentration ◽  
Microscopy Study ◽  
Lattice Parameter ◽  
Electron Microscopy Study ◽  
Bulk Materials ◽  
Thin Foils ◽  
Transmission Electron ◽  
Coating Method

AbstractBoth La and Nd–doped PZT, i.e., PLZT and PNZT, ferroelectric thin films were prepared by the metalorganic deposition (MOD) process. The precursor solutions used were derived from lead acetate, lanthanum acetylacetonate, neodymium acetate, zirconium n–propoxide, and titanium iso–propoxide. The dopant concentration of the films analyzed by electron microprobe indicated a one–to–one correspondence between film composition and the composition of the precursor from which the film was made. In this study, the effects of Nd and La dopants in PZT films on Curie temperature was determined by in–situ hot–stage TEM and compared with those of bulk materials. Lattice parameter and phase transformation were determined by both X–ray and electron diffraction. Our observations were: (1) Curie temperature decreases with increasing dopant concentration for both thin foils and bulk ceramics, (2) for a given dopant concentration, Curie temperature and crystal tetragonality of PNZT thin foils is lower than those of PLZT samples, (3) Curie temperature of thin foils was found to be less than those of the corresponding bulk materials, and (4) ferroelectric domains is easily observed in both PLZT and PNZT TEM specimens prepared by the spin–coating method.

scholarly journals Investigation of Thermal Stability and Reactivity of Rh Nanoclusters on an Ultrathin Alumina Film

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 971 ◽  
Author(s):  
Zhen-He Liao ◽  
Po-Wei Hsu ◽  
Ting-Chieh Hung ◽  
Guan-Jr Liao ◽  
Zhao-Ying Chern ◽  
...  
Keyword(s):  
Morphological Evolution ◽  
Cluster Structure ◽  
Total Surface Area ◽  
Lattice Parameter ◽  
Temperature Tolerance ◽  
High Reactivity ◽  
Alumina Film ◽  
Surface Probe ◽  
Fcc Phase ◽  
Small Clusters

We studied the structural and morphological evolution of Rh clusters on an ordered ultrathin alumina film grown on NiAl(100) in annealing processes, under ultrahigh vacuum conditions and with various surface probe techniques. The Rh clusters, prepared on vapor deposition of Rh onto the alumina film at 300 K, had an fcc phase and grew in the (100) orientation; the annealing altered the cluster structure little—the lattice parameter decreased by a factor <2%—but the cluster morphology significantly. With elevated temperature, small clusters (diameter ≤1.5 nm) decreased little in size; in contrast, large clusters (diameter ≥2.0 nm) varied in a complex manner—their mean diameter decreased to about 1.5 nm on annealing to 450 K, despite their similar height, while it increased to above 2.0 nm at temperature ≥570 K. This atypical decrease in size was governed predominantly by energetics. Such a reduced size enhanced the total surface area as well as the reactivity of the clusters toward methanol decomposition, so increased the production of D2 (H2) and CO from decomposed methanol-d4 (or methanol). The result implies a higher temperature tolerance for Rh clusters on the alumina film and a practical approach to prepare small Rh clusters with high reactivity.

scholarly journals Correlating the lattice parameter and Curie temperature of γ-Ni in Fe-Ni-base alloys

AIP Advances ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 055126 ◽  
Author(s):  
K. S. Anand ◽  
D. Goswami ◽  
P. P. Jana ◽  
J. Das
Keyword(s):  
Curie Temperature ◽  
Lattice Parameter

Synthesis of Undoped and Manganese-Doped HgTe Nanoparticles Using [Hg(TeCH2CH2NMe2)2] as a Single Source Precursor

2008 ◽  
Vol 8 (9) ◽  
pp. 4500-4505 ◽  
Author(s):  
Gotluru Kedarnath ◽  
Sandip Dey ◽  
Vimal K. Jain ◽  
Gautam K. Dey ◽  
Ramakant M. Kadam
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Lattice Parameter ◽  
Crystalline Solid ◽  
Single Source ◽  
Epr Spectrum ◽  
Single Source Precursor ◽  
Ferromagnetic Ordering ◽  
Mn Doped

The Reaction of [HgCl2(tmeda)] with NaTeCH2CH2NMe2 gave a mercury tellurolate, [Hg(TeCH2CH2·NMe2)2] (1) as a yellow crystalline solid, which was characterized by elemental analysis, UV-vis, mass and NMR (1H, 13C, 125Te, 199Hg) spectroscopy. Thermolysis of 1 in hexadecylamine (HDA) at 90 °C in the absence and presence of Mn(OAc)2·4H2O gave undoped and Mn-doped HgTe nanoparticles which were characterized by XRD, EDAX, TEM, EPR and magnetic measurements. These particles could be synthesized with mean particle size of 6–7 nm (from TEM). Manganese substitution at Hg site in HgTe lead to a linear decrease in lattice parameter with increasing concentration of Mn. Magnetization measurements showed ferromagnetic ordering at room temperature with very small coercive field (Hc, 50 Oe) for Hg0.973Mn0.027 Te sample. This sample also exhibited distinct ferromagnetic resonance (FMR) in the EPR spectrum.

scholarly journals Synthesis, Spectral and Magnetic Studies of Newly Mixed-Ligand Complexes of 4-Formyl-Acetanilide Thiosemicarbazone and 3,4-Dihydrocinnamic Acid with Some Metal Ions

2010 ◽  
Vol 7 (s1) ◽  
pp. S594-S600 ◽  
Author(s):  
Shayma A. Shaker
Keyword(s):  
Metal Ions ◽  
Magnetic Measurements ◽  
Electronic Spectroscopy ◽  
Bidentate Ligand ◽  
Magnetic Studies ◽  
Tetrahedral Geometry ◽  
H Nmr ◽  
Analysis Determination ◽  
Solid Complexes

New complexes with thiosemicarbazone derivative and 3, 4-dihydrocinnamic acid were prepared and characterized by elemental analysis, determination of metal, IR,1H NMR, electronic spectroscopy and magnetic measurements. The thiosemicarbazone derivative forms bidentate ligand complexes of the general formula, [M(Thz)(Caf)] where Thz = 4-formyl- acetanilide thiosemicarbazone, Caf = 3,4-dihydrocinnamic acid and M=Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+and Pb2+. The IR and1H NMR spectra indicates that the (Thz) was coordinated with the metal ions through the N and S atoms and the (Caf) was negatively charged bidentat ligand and was coordinated with the metal ions through the two O atoms. Electronic spectra and magnetic susceptibility measurements of the solid complexes indicates the tetrahedral geometry around the Mn2+, Fe2+, Co2+, Ni2+, Zn2+, Cd2+and irregular tetrahedral geometry around Pb2+ion while the Cu2+complex has squar planer geometry.

Cation distribution dependent magnetic properties in CoCr2−xFexO4 (x = 0.1 to 0.5): EXAFS, Mössbauer and magnetic measurements

2017 ◽  
Vol 46 (31) ◽  
pp. 10300-10314 ◽  
Author(s):  
D. Kumar ◽  
A. Banerjee ◽  
A. Mahmoud ◽  
Chandana Rath
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Curie Temperature ◽  
Cation Distribution ◽  
Magnetic Measurements ◽  
Magnetic Transitions ◽  
Ferrimagnetic Phase ◽  
Evolution Of Structure ◽  
Lock In

Evolution of structure and rich magnetic transitions such as paramagnetic to ferrimagnetic phase transition at Curie temperature (TC), spiral ordering temperature (TS) and lock-in temperature (TL) have been discussed in CoCr2O4 spinel multiferroic after substituting Fe.

Residual Stresses and Magnetoelastic Coupling in Ultrathin Fe Films Deposited on GaAs(001)

2000 ◽  
Vol 615 ◽  
Author(s):  
P. Gergaud ◽  
C. Lallaizon ◽  
M. Putero ◽  
B. Lépine ◽  
O. Thomas ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Magnetic Measurements ◽  
Strain Tensor ◽  
Magnetic Thin Films ◽  
Lattice Parameter ◽  
Parameter Mismatch ◽  
Magnetoelastic Coupling ◽  
Small Lattice ◽  
Open Question

ABSTRACTThe growing interest in the behavior of magnetic thin films on semiconductor substrates is due in part to their potential application in spin-sensitive heterostructure devices. High-quality epitaxial Fe(001) thin films can be grown on GaAs(001) substrates because of the small lattice parameter mismatch (−1.4%). Magnetic measurements performed on Fe films thinner than 3 nm have shown that such films exhibit an in-plane uniaxial magnetic anisotropy although an ideal bcc Fe(001) film should have fourfold symmetry. The source of this uniaxial component remains an open question and one of the mechanisms which may contribute to this is the epitaxial strain, through magnetoelastic coupling. Very small strains anisotropies are able to modify the magnetic anisotropy of iron thin films. Moreover the sign and magnitude of the magnetoelastic coupling seem to depend on the film thickness or film strain [1]. In this study, the strain tensor components in two Fe thin films (1.7 and 3.0 nm thick) has been measured by XRD. The magnetic free energy has been derived, using the strain tensor components.

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