Temperature-dependant phase transformation of NixFey−xOz nanoferrites: their dielectric and magnetic properties

ABSTRACTThe phase transformation and the exchange coupling in (Ndo095Lao005)9.5FebaICOsNb 2BI05 have been investigated. Nanocomposites were obtained by treating amorphous precursors at temperatures ranging from 650TC to 9500C for 10 minutes. The magnetic properties were characterized via the vibrating sample magnetometer (VSM). X-ray diffraction (XRD), thermomagnetic analysis (TMA), and transmission electron microscopy (TEM) were used to perform phase identification, measure grain size, and analyze phase distribution. The strength of the exchange coupling between the magnetically hard and soft phases in the corresponding nanocomposite was analyzed via the AM-versus-H plot. It was found that the remanence (Br), coercivity (Hci), and maximum energy product (BHmax) obtained were affected by the magnetic phases present as well as the grain size of constituent phases and their distribution. The optimal magnetic performance, BHm, occurred between 700°C to 750°C, where the crystallization has completed without excessive grain growth. TMA and TEM indicated that the system was composed of three phases at this point, Nd2(Fe Co) 14B, ca-Fe, and Fe3B. The exchange coupling interaction among these phases was consistently described via the AM-versus-H plot up to 750°C. The Br, Hci, and BHmax degraded severely when the thermal treatment temperature increased from 750°C. This degradation may be attributed to the grain growth of the main phases, from 45 to 68nm, and the development of precipitates, which grew from 5nm at 750°C to 12nm at 850°C. Moreover, the amount of the precipitates was found to increase with the thermal treatment temperatures. The precipitates, presumably borides, may cause a decrease in the amount of the a-Fe and Fe 3B and result in a redistribution of the Co in the nanocomposites. The increase of the Co content in the Nd 2(Fe Co) 14B may explain the increase of its Curie temperature with the thermal treatment temperatures. In this paper, we examine the impacts of these factors on the magnetic properties of (Ndo 95Lao 05)9 5FebaICosNb2B10.5 nanocomposite.

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Phase transformation, grain refinement and magnetic properties in melt-spun SmCo7−x(Cr3C2)x (x=0–0.25) ribbons

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2009.01.050 ◽

2009 ◽

Vol 479 (1-2) ◽

pp. 78-81 ◽

Cited By ~ 10

Author(s):

L.Y. Li ◽

A. Yan ◽

J.H. Yi ◽

G.T. Zhang ◽

W. Xie ◽

...

Keyword(s):

Magnetic Properties ◽

Phase Transformation ◽

Grain Refinement ◽

Melt Spun

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The Phase Transformation and Magnetic Properties in Ni-Mn-In Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.712-715.54 ◽

2013 ◽

Vol 712-715 ◽

pp. 54-57 ◽

Cited By ~ 2

Author(s):

Hai Le Yan ◽

Zong Bin Li ◽

Chun Yang Zhang ◽

Yu Dong Zhang ◽

Claude Esling ◽

...

Keyword(s):

Magnetic Properties ◽

Phase Transformation ◽

Structural Transition ◽

Alloy Composition ◽

Ferromagnetic Shape Memory Alloys ◽

Scanning Calorimetry ◽

Phase Transition Temperatures ◽

Ferromagnetic Shape Memory ◽

Curie Temperatures ◽

Magnetization Change

The phase transformation and magnetic properties of Heusler-type Ni50Mn50-xInx(x=10~16) ferromagnetic shape-memory alloys have been systemically investigated by differential scanning calorimetry and vibrating sample magnetometry. It is found that the phase transition temperatures show a linear relationship with the In concentration and the curie temperatures of austenite phases are not sensitive to the alloy composition. The existence of large magnetization change during the magneto-structural transition is the origin of magnetic-field-induced transformation effect.

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The Effect of Drawing Deformation Rate Induced Inhomogeneous Local Distortion on Phase Transformation of 304H Stainless Wire

Metals ◽

10.3390/met10101304 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1304

Author(s):

Qinhua Xu ◽

Zhixian Peng ◽

Jianxin Zhu ◽

Mingyang Li ◽

Yong Zong ◽

...

Keyword(s):

Magnetic Properties ◽

Phase Transformation ◽

Heat Generation ◽

Martensite Transformation ◽

Local Strain ◽

Cold Drawing ◽

Element Distribution ◽

Martensite Phase ◽

Single Strain ◽

Area Reduction

The micro/macro magnetic properties, local element distribution, martensite transformation, and mechanical properties of 304H stainless wires are determined for two cold drawing chains. Finite element simulations are used to analyse the local strain and heat generation. The results show that there is obvious inhomogeneity in the magnetic properties, strain/stress relationship, and strain-induced heat within the drawn wires. Comparing wires with the same total strain, a larger area reduction of previous drawing processes contributes to a higher volume of the martensite phase, while a smaller area reduction of the first process results in an inhibited phase transformation. A higher single strain in the first drawing process leads to additional heat generation at the subsurface of the wire, which would eventually retard the martensite transformation. The inhomogeneous deformation-induced differences in the grain size affect the stability of austenite and transform the final martensite.

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Influence of Hydrofluoric Acid Leaching and Roasting on Mineralogical Phase Transformation of Pyrite in Sulfidic Mine Tailings

Minerals ◽

10.3390/min10060513 ◽

2020 ◽

Vol 10 (6) ◽

pp. 513 ◽

Cited By ~ 5

Author(s):

Babak Koohestani ◽

Ahmad Khodadadi Darban ◽

Pozhhan Mokhtari ◽

Esmaeel Darezereshki ◽

Erol Yilmaz ◽

...

Keyword(s):

Magnetic Properties ◽

Phase Transformation ◽

Iron Oxides ◽

Mine Tailings ◽

Hydrofluoric Acid ◽

Surface Characterization ◽

Acid Leaching ◽

Roasting Process ◽

Pyrite Content ◽

Mineralogical Phase

Under the oxidative roasting process, pyrite, as a major mineral in sulfidic mine tailings, can transform to iron oxides. Generated iron oxides, if exhibiting enough magnetic properties, can be recovered via magnetic separation resulting in partial mine tailings valorization. However, due to the presence of various minerals and sintering possibility, it is advantageous to remove impurities and increase the pyrite content of mine tailings prior to the roasting procedure. In this case, hydrofluoric acid that has no influence on pyrite can be used to leach most inorganic minerals, including aluminosilicates. Therefore, this study investigated and compared the influence of the roasting process with and without hydrofluoric acid leaching pretreatment on mineralogical phase transformation of pyrite and magnetic properties of thermally generated minerals. Several tests and analyses were performed to study mineralogical phase transformation, morphology, elemental composition, surface characterization, and magnetic properties. Results of this study indicated that without acid leaching pretreatment, pyrite was mainly transformed to hematite. However, via acid leaching, fluorine, as a more electronegative element over oxygen, entered the compound and neglected the role of oxygen in thermal oxidation, instead reducing sulfur content of pyrite to only form pyrrhotite.

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Effect of Co addition on martensitic phase transformation and magnetic properties of Mn50Ni40-xIn10Cox polycrystalline alloys

Intermetallics ◽

10.1016/j.intermet.2011.08.001 ◽

2011 ◽

Vol 19 (12) ◽

pp. 1839-1848 ◽

Cited By ~ 29

Author(s):

Zhigang Wu ◽

Zhuhong Liu ◽

Hong Yang ◽

Yinong Liu ◽

Guangheng Wu

Keyword(s):

Magnetic Properties ◽

Phase Transformation ◽

Martensitic Phase ◽

Martensitic Phase Transformation ◽

Polycrystalline Alloys ◽

Co Addition

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PHASE EVOLUTION AND MAGNETIC PROPERTIES OF FEPT-PTTE2 NANORODS

International Journal of Modern Physics B ◽

10.1142/s0217979209062992 ◽

2009 ◽

Vol 23 (17) ◽

pp. 3573-3578

Author(s):

QINGYU YAN ◽

AIDONG LI

Keyword(s):

Magnetic Properties ◽

Phase Transformation ◽

High Temperature ◽

Annealing Temperature ◽

Phase Evolution ◽

Polyol Process ◽

Phase Ratio ◽

High Temperature Annealing ◽

Two Phase

FePt - PtTe 2 two phase nanorods have been produced by a polyol process. The shape and magnetic properties of two phase nanorods with different phase ratio are investigated. L10 phase transformation of FePt in the nanorods has been accomplished at annealing temperature as low as 400 °C with Hc above 500mT. High temperature annealing causes the disintegration of the nanorods due the melting/evaporation of Te element.

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