scholarly journals Thermal Stability, Blocking Regime and Superparamagnetic Behavior in Mn-Al-C Melt Spun Ribbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2898
Author(s):  
Alina Daniela Crisan ◽  
Aurel Leca ◽  
Ioan Dan ◽  
Ovidiu Crisan
Keyword(s):  
Phase Transformation ◽  
Melt Spinning ◽  
Hysteresis Loops ◽  
Spin Reorientation ◽  
Zero Field ◽  
Superparamagnetic Behavior ◽  
Maximum Magnetization ◽  
Good Potential ◽  
Complex Structural ◽  
The Stability

Alloys possessing nominal compositions Mn53Al45C2 and Mn52Al46C2 were prepared by the melt spinning method and were subjected to complex structural, morphological and magnetic investigations. As these alloys can exhibit tetragonal L10-type and τ phase, they have good potential as rare earth (RE)—free magnets. It is, therefore, important to monitor the ε–τ phase transformation and the stability and the magnetic features of the tetragonal phase in an entire temperature interval. By using synchrotron X-ray diffraction, it has been proven that the ε–τ phase transformation occurs gradually, with the τ phase becoming predominant only after 450 °C. Moreover, this phase has been proven to be quite stable without any grain growth even at the highest temperature investigated at 800 °C. Low temperature behavior was thoroughly investigated by using a complex combination of major and minor hysteresis loops combined with the zero field cooled-field cooled magnetization protocols (ZFC-FC). Two different regimes, blocking and superparamagnetic, were documented. A spin reorientation transition was proven to occur at 55 K while a maximum magnetization observed in ZFC-FC curves proved that at about 75 K, a transition from ferro to superparamagnetic state occurs. The existence of a blocking regime below 55 K that is characteristic to nanogranular systems with superparamagnetic behavior has shown further development towards obtaining RE-free magnets.

scholarly journals Structural transition and magnetic properties of high Cr-doped BiFeO3 ceramic

Cerâmica ◽  
2020 ◽  
Vol 66 (378) ◽  
pp. 114-118
Author(s):  
S. S. Arafat
Keyword(s):  
Magnetic Properties ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Phase Diagram ◽  
Magnetic Sensors ◽  
Spin Reorientation ◽  
X Ray Diffraction ◽  
Maximum Magnetization ◽  
Ion Doping ◽  
Crystal Structure Transformation

Abstract Magnetic properties of BiFe1-xCrxO3 perovskite-type solids reaction synthesized at high pressure were investigated and a magnetic phase diagram was established. X-ray diffraction data revealed a crystal structure transformation from rhombohedral to monoclinic as Cr3+ ions substituted Fe ions in the samples. Néel temperature TN and spin-reorientation temperature TSR were determined from dM/dT by measuring the temperature dependence of magnetization (M-T). The magnetization results indicated that TN and TSR were strongly dependent on Cr3+ ion doping; both TN and TSR decreased with the increase of Cr3+ doping. The magnetic hysteresis loops investigated at room temperature reflected an antiferromagnetic behavior from x= 0.4 to 0.6 and weak ferromagnetic at x=1.0. Besides, the remnant magnetization Mr and maximum magnetization Mmax increased with increasing x from 0.4 up to 1.0. The Cr doping was found to be helpful in reducing coercivity Hc for the magnetic samples from x= 0.4 to 0.8 and their applications as magnetic sensors are possible.

An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

2015 ◽  
Vol 10 (2) ◽  
pp. 2663-2681
Author(s):  
Rizk El- Sayed ◽  
Mustafa Kamal ◽  
Abu-Bakr El-Bediwi ◽  
Qutaiba Rasheed Solaiman
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Melt Spinning ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
Microstructural Analysis ◽  
Alloy System ◽  
Antimony Content ◽  
The Stability ◽  
Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as melt–spun ribbons  as a function of antimony content .The stability  of these structures has  been  related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition.  The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes. 

Coercivity and spin reorientation transitions in Nd-Fe-B nanocomposites prepared by melt spinning

1997 ◽  
Vol 33 (3) ◽  
pp. 2366-2368 ◽  
Author(s):  
M. Dahlgren ◽  
X.C. Kou ◽  
R. Grossinger ◽  
J.F. Liu ◽  
I. Ahmad ◽  
...  
Keyword(s):  
Melt Spinning ◽  
Spin Reorientation

scholarly journals Real-space observation of ferroelectrically induced magnetic spin crystal in SrRuO3

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. D. Seddon ◽  
D. E. Dogaru ◽  
S. J. R. Holt ◽  
D. Rusu ◽  
J. J. P. Peters ◽  
...  
Keyword(s):  
Hall Effect ◽  
Density Functional ◽  
Hysteresis Loops ◽  
Real Space ◽  
Zero Field ◽  
Force Microscopy ◽  
Switching Regime ◽  
Conflicting Evidence ◽  
Magnetic Spin

AbstractUnusual features in the Hall Resistivity of thin film systems are frequently associated with whirling spin textures such as Skyrmions. A host of recent investigations of Hall Hysteresis loops in SrRuO3 heterostructures have provided conflicting evidence for different causes for such features. We have constructed an SrRuO3-PbTiO3 (Ferromagnetic – Ferroelectric) bilayer that exhibits features in the Hall Hysteresis previously attributed to a Topological Hall Effect, and Skyrmions. Here we show field dependent Magnetic Force Microscopy measurements throughout the key fields where the ‘THE’ presents, revealing the emergence to two periodic, chiral spin textures. The zero-field cycloidal phase, which then transforms into a ‘double-q’ incommensurate spin crystal appears over the appearance of the ‘Topological-like’ Hall effect region, and develop into a ferromagnetic switching regime as the sample reaches saturation, and the ‘Topological-like’ response diminishes. Scanning Tunnelling Electron Microscopy and Density Functional Theory is used to observe and analyse surface inversion symmetry breaking and confirm the role of an interfacial Dzyaloshinskii–Moriya interaction at the heart of the system.

Features of Semiconductors during Nanoindentation

2003 ◽  
Vol 779 ◽  
Author(s):  
Asta Richter ◽  
Bodo Wolf ◽  
Roger Smith ◽  
Margita Günther
Keyword(s):  
Phase Transformation ◽  
Hysteresis Loops ◽  
Maximum Load ◽  
Depth Sensing ◽  
Ion Energy ◽  
Loop Area ◽  
Area Reduction ◽  
Boron Implantation ◽  
The Impact ◽  
Constant Maximum

AbstractSi and InSb were subject to depth sensing multi-cycling nanoindentation. The load-depthcurves exhibited hysteresis loops which are explained in terms of pressure induced phase transformations. In order to study the impact of crystal distortions on phase transformation, the specimens were subject to boron implantation (ion energy 180 keV) of different implantation doses (1014 to 1017 ions/cm2) and indented without annealing. In InSb, the hysteresis loops disappeared after implantation of 1016 ions/cm2, and for Si with its stronger bonds, a dose of 3*1016/cm2 is required for the same effect. Indentation cycling with constant maximum load results in a sudden disappearance of the hysteresis loop after a small gradual loop area reduction during the first initial cycles.

scholarly journals Phase Transformation of Cr(VI)-Adsorbed Ferrihydrite at Different pH in The Presence of Mn(II): Fate of Mn(II) and Cr(VI)

2021 ◽  
Author(s):  
Zecong Ding ◽  
Fenglian Fu ◽  
Guangzhao Sun ◽  
Chujia Ye
Keyword(s):  
Phase Transformation ◽  
Heavy Metal Ions ◽  
Solid Phase ◽  
Transformation Products ◽  
Transformation Process ◽  
Toxic Heavy Metal ◽  
Chromium Vi ◽  
Initial Ph ◽  
The Stability ◽  
Mn Concentration

Abstract Ferrihydrite is an important sink for the toxic heavy metal ions, such as chromium(VI). As ferrihydrite is thermodynamically unstable and gradually transforms into hematite and goethite, the stability of Cr(VI)-adsorbed ferrihydrite is environmentally significant. This study investigated the phase transformation of Cr(VI)-adsorbed ferrihydrite at different pH in the presence of aqueous Mn(II), as well as the fate of Mn(II) and Cr(VI) in the transformation process of ferrihydrite. Among the ferrihydrite transformation products, hematite was dominant, and goethite was minor. The pre-adsorbed Cr(VI) inhibited the conversion of ferrihydrite to goethite at initial pH 3.0, whereas little amount of adsorbed Mn(II) favored the formation of goethite at initial pH 7.0. After the aging process, Cr species in solid phase existed primarily as Cr(III) in the presence of Mn(II) at initial pH 7.0 and 11.0. The aqueous Mn concentration was predominantly unchanged at initial pH 3.0, whereas the aqueous Mn(II) was adsorbed onto ferrihydrite or form Mn(OH)2 precipitates at initial pH 7.0 and 11.0, promoting the immobilization of Cr(VI). Moreover, the oxidation of Mn(II) occurred at initial pH 7.0 and 11.0, forming Mn(III/IV) (hydr)oxides.

Exchange Bias Properties in Bulk Ni45Co5Mn38Sn12 Heusler Alloy

2014 ◽  
Vol 875-877 ◽  
pp. 272-276 ◽  
Author(s):  
Chao Jing ◽  
Ye Jun Yang ◽  
Dong Hua Yu ◽  
Zhe Li ◽  
Xiao Long Wang ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Exchange Bias ◽  
Heusler Alloy ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Bias Field ◽  
Magnetic Hysteresis Loop ◽  
Zero Field ◽  
Co Substitution ◽  
Exchange Bias Field

We report the exchange bias properties in the bulk Ni45Co5Mn38Sn12quaternary Heusler alloy. The ferromagnetic (FM) –antiferromagnetic (AFM) interactions get reinforced after the Co substitution for Ni in the Ni-Mn-Sn alloy, which increase the exchange bias field (HE). A maximum shift in hysteresis loops of 306 Oe was observed in the 10 kOe field cooled sample. The origin of this large exchange bias field has been discussed. Magnetic hysteresis loop obtained in the zero field cooled (ZFC) mode shows double-shifted loop, and the reason of this phenomenon has been explained in detail.

Magnetic Properties of Nanocrystalline (Nd,R)-(Fe,Co)-B (R = Pr, Ho) Alloys after Melt Spinning, Severe Plastic Deformation and Heat Treatment

2020 ◽  
Vol 312 ◽  
pp. 235-243
Author(s):  
Lev Aleksandrovich Ivanov ◽  
Tatiana P. Kaminskaya ◽  
Irina Semenovna Tereshina ◽  
Vladislav Davydov ◽  
Vladimir V. Popov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Melt Spinning ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Nanocrystalline State ◽  
Force Microscopy ◽  
Atomic Force ◽  
Deformation And Heat Treatment

Magnetic force microscopy (MFM) and magnetometry, scanning electron microscopy (SEM) and atomic force microscopy (AFM) are used to study the magnetic and structural properties of the (Nd,Pr)-Fe–B and (Nd,Ho)-(Fe,Co)-B alloys. The alloys are synthesized using an arc or induction furnaces. The nanocrystalline state of the (Nd,Ho)-(Fe,Co)-B alloys is reached by two techniques, namely, melt spinning (MS) and severe plastic deformation (SPD). Hydrogenation and multistage treatment of (Nd,Ho)-(Fe,Co)-B alloys, which includes severe plastic deformation of melt-quenched ribbons and subsequent heat treatment, is also used. The surface morphology and domain structure of samples are studied. These pictures are used to interpret the observed magnetic hysteresis loops of the samples. It was found that multistage treatment allows one to obtain samples with higher values of coercivity due to the formation of a special microstructure with oval grain (the aspect ratio equal to ∼ 3).

scholarly journals Iron-Doped Lithium Tantalate Thin Films Deposited by Magnetron Sputtering: A Study of the Iron Role in the Structure and the Derived Magnetic Properties

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 50 ◽  
Author(s):  
Sergio David Villalobos Mendoza ◽  
José Trinidad Holguín Momaca ◽  
José Trinidad Elizalde Galindo ◽  
Diana María Carrillo Flores ◽  
Sion Federico Olive Méndez ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Blocking Temperature ◽  
Ferromagnetic Behavior ◽  
Zero Field ◽  
Cooling Curves ◽  
X Ray Diffraction ◽  
Field Cooling

Fe-doped LiTaO3 thin films with a low and high Fe concentration (labeled as LTO:Fe-LC and LTO:Fe-HC, respectively) were deposited by magnetron sputtering from two home-made targets. The dopant directly influenced the crystalline structure of the LiTaO3 thin films, causing the contraction of the unit cell, which was related to the incorporation of Fe3+ ions into the LiTaO3 structure, which occupied Li positions. This substitution was corroborated by Raman spectroscopy, where the bands associated with Li-O bonds broadened in the spectra of the samples. Magnetic hysteresis loops, zero-field cooling curves, and field cooling curves were obtained in a vibrating sample magnetometer. The LTO:Fe-HC sample demonstrates superparamagnetic behavior with a blocking temperature of 100 K, mainly associated with the appearance of Fe clusters in the thin film. On the other hand, a room temperature ferromagnetic behavior was found in the LTO:Fe-LC layer where saturation magnetization (3.80 kAm−1) and magnetic coercivities were not temperature-dependent. Moreover, the crystallinity and morphology of the samples were evaluated by X-ray diffraction and scanning electron microscopy, respectively.

scholarly journals Effects of High Magnetic Fields on Phase Transformations in Amorphous Nd2Fe14B

2019 ◽  
Vol 5 (1) ◽  
pp. 16 ◽  
Author(s):  
Michael Kesler ◽  
Brandt Jensen ◽  
Lin Zhou ◽  
Olena Palasyuk ◽  
Tae-Hoon Kim ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Melt Spinning ◽  
Magnetic Behavior ◽  
Phase Evolution ◽  
High Magnetic Fields ◽  
Phase Identification ◽  
Zero Field ◽  
Transmission Electron ◽  
Size And Morphology ◽  
Applied Fields

We briefly summarize the results from a set of experiments designed to demonstrate the effects of high magnetic fields applied during thermal annealing of amorphous Nd2Fe14B produced through melt-spinning. A custom-built differential scanning calorimeter was used to determine the crystallization temperatures in zero-field and in applied fields of 20 kOe and 90 kOe, which guided subsequent heat treatments to evaluate phase evolution. X-ray diffraction was used for phase identification and transmission electron microscopy was employed for observation of the crystallite size and morphology. Magnetization measurements were also used to evaluate the resulting magnetic phases after thermomagnetic processing. While the applied magnetic fields do not appear to affect the crystallization temperature, significant effects on the kinetics of phase evolution are observed and correlated strongly to the magnetic behavior.

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