scholarly journals Magnetic Properties of Heusler Alloys and Nanoferrites

2021 ◽  
Author(s):  
Devinder Singh ◽  
Kuldeep Chand Verma
Keyword(s):  
Magnetic Properties ◽  
Spinel Structure ◽  
Heusler Alloys ◽  
Magnetic Interactions ◽  
Zero Field ◽  
Important Class ◽  
Magnetization Curves ◽  
X Ray Diffraction ◽  
Response Measurement ◽  
Ga Content

In this chapter, results of our recent investigations on the structural, microstructural and magnetic properties of Cu-based Heusler alloys and MFe2O4 (M = Mn, Fe, Co, Ni, Cu, Zn) nanostructures will be discussed. The chapter is divided into two parts, the first part describes growth and different characterizations of Heusler alloys while in the second part magnetic properties of nano-ferrites are discussed. The Cu50Mn25Al25-xGax (x = 0, 2, 4, 8 and 10 at %) alloys have been synthesized in the form of ribbons. The alloys with x ≤ 8 show the formation of Heusler single phase of the Cu2MnAl structure. Further increase of Ga content gives rise to the formation of γ-Cu9Al4 type phase together with Cu2MnAl Heusler phase. The alloys are ferromagnetically ordered and the saturation magnetization (Ms) decreases slightly with increasing Ga concentration. Annealing of the ribbons significantly changes the magnetic properties of Cu50Mn25Al25-xGax alloys. The splitting in the zero field cooled (ZFC) and field cooled (FC) magnetization curves at low temperature has been observed for alloys. Another important class of material is Nanoferrites. The structural and magnetization behaviour of spinel MFe2O4 nanoferrites are quite different from that of bulk ferrites. X-ray diffraction study revealed spinel structure of MFe2O4 nanoparticles. The observed ferromagnetic behaviour of MFe2O4 depends on the nanostructural shape as well as ferrite inversion degree. The magnetic interactions in Ce doped CoFe2O4 are antiferromagnetic that was confirmed by zero field/field cooling measurements at 100 Oe. Log R (Ω) response measurement of MgFe2O4 thin film was taken for 10–90% relative humidity (% RH) change at 300 K.

scholarly journals Magnetic Attributes of NiFe2O4 Nanoparticles: Influence of Dysprosium Ions (Dy3+) Substitution

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 820 ◽  
Author(s):  
Munirah Abdullah Almessiere ◽  
Y. Slimani ◽  
H. Güngüneş ◽  
S. Ali ◽  
A. Manikandan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spin Glass ◽  
Ac Susceptibility ◽  
Freezing Temperature ◽  
Magnetic Interactions ◽  
Blocking Temperature ◽  
Zero Field ◽  
X Ray Diffraction ◽  
Slowing Down ◽  
Transmission Electron

This paper reports the influence of dysprosium ion (Dy3+) substitution on the structural and magnetic properties of NiDyxFe2−xO4 (0.0 ≤ x ≤ 0.1) nanoparticles (NPs) prepared using a hydrothermal method. The structure and morphology of the as-synthesized NPs were characterized via X-ray diffraction (XRD), scanning and transmission electron microscope (SEM, and TEM) analyses. 57Fe Mössbauer spectra were recorded to determine the Dy3+ content dependent variation in the line width, isomer shift, quadrupole splitting, and hyperfine magnetic fields. Furthermore, the magnetic properties of the prepared NPs were also investigated by zero-field cooled (ZFC) and field cooled (FC) magnetizations and AC susceptibility measurements. The MZFC (T) results showed a blocking temperature (TB). Below TB, the products behave as ferromagnetic (FM) and act superparamagnetic (SPM) above TB. The MFC (T) curves indicated the existence of super-spin glass (SSG) behavior below Ts (spin-glass freezing temperature). The AC susceptibility measurements confirmed the existence of the two transition temperatures (i.e., TB and Ts). Numerous models, e.g., Neel–Arrhenius (N–A), Vogel–Fulcher (V–F), and critical slowing down (CSD), were used to investigate the dynamics of the systems. It was found that the Dy substitution enhanced the magnetic interactions.

MAGNETIC PROPERTIES OF CO-PRECIPITATED MnZn FERRITE-SiO2 COMPOSITES

2007 ◽  
Vol 21 (15) ◽  
pp. 2669-2677 ◽  
Author(s):  
M. U. ISLAM ◽  
M. AZHAR KHAN ◽  
ZULFIQAR ALI ◽  
SHAHIDA B. NIAZI ◽  
M. ISHAQUE ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Characteristic Temperature ◽  
Magnetic Interactions ◽  
X Ray Diffraction ◽  
Mnzn Ferrite ◽  
X Ray ◽  
Splitting Factor ◽  
Low Field ◽  
Co Precipitation

A series of composite ferrites with chemical formula (1–x) [Mn0.5Zn0.5Fe2O4] ·x[ SiO 2](x = 0.0, 0.20, 0.30, 0.40, 0.50) were prepared by the co-precipitation technique. The samples were finally sintered at 1150°C followed by air quenching. The x-ray diffraction analysis confirms the phases precipitated out in the samples. AC magnetic susceptibility of these samples has been measured using the low field mutual inductance technique over the temperature range 298 K to 550 K at a frequency of 250 Hz. The magnetic parameters like Curie constant, C, Curie temperature, Tc, Lande splitting factor, g, effective magnetic moment, P eff , exchange integral, J/kB, and characteristic temperature, θ( K ) were calculated. The reciprocal of susceptibility versus temperature curves of each sample follows the Curie Weiss behaviour above the Curie temperature. Below the Curie temperature, all the samples show the ferrimagnetic behaviour. It was concluded that the magnetic properties were enhanced by the addition of silicon as is evident by the variation of magnetic interactions J, with Si -concentration and followed subsequently by the P eff , θ( K ) and Tc etc.

Spinel Structured Iron Gallium Oxynitride - Fe2GaO2N2

2021 ◽  
Vol 1160 ◽  
pp. 45-50
Author(s):  
Savitha Kadencheri Unnikrishnan
Keyword(s):  
Magnetic Properties ◽  
Chemical Composition ◽  
Spinel Structure ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
R Factor ◽  
Novel Material ◽  
Optical And Magnetic Properties ◽  
Co Precipitation

A facile method was successfully developed to prepare Ternary oxynitride of iron and gallium. Initially mixed oxyhydroxides of Iron and gallium were prepared by co-precipitation method. Then this was nitrided using urea and agar in presence of ammonia at 900°C, which gave mixed cation oxynitride . This mixed oxynitride was characterized using XRD, XPS and SEM. The X-ray diffraction pattern of the Fex’GaxOyNz phase was refined within the cubic spinel structure (space group Fd-3m), using the fullprof program. On assuming 3+ oxidation state for half of iron and whole of gallium, the chemical composition of the oxynitride spinel determined by the X-ray analysis is Fe2GaN2O2. The refinement using these parameters resulted in a good fit to the observed diffraction data, with a crystallographic R factor of 5.92. This ternary oxynitride of iron and gallium is a novel material which can give unique optical and magnetic properties.

Investigation of Structural, Electrical and Magnetic Properties of Mixed Ferrite System

2014 ◽  
Vol 1047 ◽  
pp. 119-122
Author(s):  
Nidhi M. Astik ◽  
G.J. Baldha
Keyword(s):  
Magnetic Properties ◽  
Spinel Structure ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Stoichiometric Mixture ◽  
Ceramic Method ◽  
Oxygen Ions ◽  
Electrical And Magnetic Properties ◽  
Metallic Cations ◽  
Polycrystalline Form

The mineral having chemical compositional formula MgAl2O4 is called “spinel”. The ferrites crystallize in spinel structure are known as spinel-ferrites or ferro-spinels. The spinel structure has an fcc cage of oxygen ions and the metallic cations are distributed among tetrahedral (A) and octahedral (B) interstitial voids (sites). A compound of Co0.85Ca0.15-yMgyFe2O4 (y=0.05, 0.10, 0.15) is synthesized in polycrystalline form, using the stoichiometric mixture of oxides with conventional standard ceramic technique and characterized by X-ray diffraction (XRD).The XRD analysis confirmed the presence of cubic structure. The intensity of each Bragg plane is sensitive to the distribution of cations in the interstitial voids of the spinel lattice. The computer program Powder X software for XRD analysis has been utilized for this purpose. The compositions of Co0.85Ca0.15-yMgyFe2O4 (y=0.05, 0.10, 0.15) ferrites have been prepared by standard ceramic method with double sintering at 950°C, 1100°C. In present study, we report the structural, electrical and magnetic properties of above said compound.

scholarly journals Fabrication and magnetic properties of hierarchical nickel microwires with nanothorns

2010 ◽  
Vol 8 (2) ◽  
pp. 434-439 ◽  
Author(s):  
Junhao Zhang ◽  
Ling Yang ◽  
Xiaofang Cheng ◽  
Jinmeng Zhang ◽  
Fucai Li
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Cooperative Effect ◽  
Magnetic Interactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

AbstractHierarchical nickel microwires with nanothorns were fabricated through a reduction of nickelous salt with hydrazine in diethanolamine. The product was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). The growth mechanism of the nickel microwires with nanothorns is proposed, based on the evolution of the structures and morphologies, which could be ascribed to the cooperative effect of the complexant of diethanolamine and inherent magnetic interactions. Magnetic properties of the product were measured at room temperature and compared with other shaped counterparts.

scholarly journals Structural, electrical and magnetic properties of the pyrochlorate Er_2-x Sr_x Ru_2O_7 (0<=x<=0.10) system

2018 ◽  
Vol 64 (3) ◽  
pp. 222 ◽  
Author(s):  
Mohamed Abatal
Keyword(s):  
Magnetic Properties ◽  
Crystal Size ◽  
Rietveld Method ◽  
Ambient Pressure ◽  
Zero Field ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Increasing Temperature

In this research, we report a detailed study of the structural, electrial and magnetic properties of the ruthenium pyrochlore with the composition (Er_2-x Sr_x) Ru_2O_7 0<=x<=0.10 prepared by solid-state reaction in air at ambient pressure.  The synthesized products were characterized using powder X-ray diffraction. The structure of the samples was refined with the Rietveld method, showing that the lattice parameters are more sensitive to the Strontium and Erbium sites. Scanning electron microscopy shows that the crystal size varies between 0.27 and 0.62 mu m. In all polycrystalline samples, the electrical resistance decreases with increasing temperature, indicating that the samples are nonmetallic. The slope of the temperature-dependent resistance profiles systematically decreases with increasing x, proving that the carrier concentration increases with increasing the Sr content. Zero-field-cooled and field cooled magnetization measurements show an irreversible behavior where the split is systematically enhanced by increasing x.

Structure and Magnetic Properties of Ga Substituted Ni-Ferrites

2013 ◽  
Vol 446-447 ◽  
pp. 68-72
Author(s):  
Ahmad Amirabadizadeh ◽  
Zobedeh Momeni Larimi ◽  
Saeideh Eghbali
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Sol Gel ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
X Ray Diffraction ◽  
Auto Ignition ◽  
Transmission Electron ◽  
Magnetic Hysteresis Loops ◽  
Ga Content

Nanocrystalline Ga doped nickel ferrite [(NiFe2-xGaxO4 (x=0.0, 0.1, 0.3, 0.5 and 0.7)] powders have been synthesized by sol-gel auto-ignition method and the effect of non-magnetic gadillum content on the nanosize particles and magnetic properties has been studied. The X-ray diffraction (XRD) revealed that the powders obtained are single phase with spinel structure. The calculated grain size from XRD data have been verified using transmission electron microscopy (TEM). TEM photograph shows that the powders consist of nanometer sized grain. The size of nanoparticles decreases as the non magnetic Ga content increases. Magnetic hysteresis loops were measured at room temperature with maximum applied magnetic field of 20 KOe. As Ga content increases, the measured magnetic hysteresis curves became border and saturation magnetization (MS) increased up to x= 0.3 and further increase of x leads the magnetization to decrease. The results are explained according to the assumed cation distribution.

scholarly journals Influence of Preparation Technology on Microstructural and Magnetic Properties of Fe2MnSi and Fe2MnAl Heusler Alloys

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 710 ◽  
Author(s):  
Yvonna Jirásková ◽  
Jiří Buršík ◽  
Dušan Janičkovič ◽  
Ondřej Životský
Keyword(s):  
Magnetic Properties ◽  
Heusler Alloys ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Preparation Technology ◽  
Arc Melting ◽  
Planar Flow Casting ◽  
Wheel Side ◽  
Mn Content ◽  
Diffraction Patterns

Microstructural and magnetic properties of the X2YZ, namely Fe2MnSi and Fe2MnAl, Heusler alloys have been studied from the viewpoint of technology for their production and for the Z element effect. First, arc melting was applied to produce button-type ingots from which samples in a form of 500 µm thick discs were cut. Second, planar flow casting technology yielded samples in a ribbon-form 2 mm wide and 20 μm thick. The checked area chemical compositions were in agreement with the nominal ones. Nevertheless, the darker square objects and smaller bright objects observed at the wheel side of the Fe2MnSi ribbon sample yielded higher Mn content at the expense of Fe. The X-ray diffraction patterns of all samples have indicated L21 structure with lattice parameters, 0.567 (1) nm for Fe2MnSi and 0.584 (1) nm for Fe2MnAl, being within an experimental error independent of production technology. On the other hand, the technology has markedly influenced the microstructure clearly pointing to the larger size of grains and grain boundaries in the disc samples. From the magnetic viewpoint, both alloys are paramagnetic at room temperature without visible influence of their production. On the contrary, the low-temperature behavior of the microscopic hyperfine parameters and the macroscopic magnetic parameters exhibits differences affected by both chemical composition and microstructure.

scholarly journals Structural, Chemical and Low Temperature Magnetic Properties of Lead Free 0.6NiFe2O4 - 0.4Na0.5Bi0.5TiO3 Magnetoelectric Composite

2021 ◽  
Author(s):  
G Jegadish Kumar ◽  
M Sarathbavan ◽  
E Senthil Kumar ◽  
M Navaneethan ◽  
K Kamala Bharathi
Keyword(s):  
Magnetic Properties ◽  
Low Temperature ◽  
Saturation Magnetization ◽  
Room Temperature ◽  
Magnetization Measurement ◽  
Magnetic Interactions ◽  
Lead Free ◽  
Zero Field ◽  
Temperature Dependent ◽  
Magnetoelectric Composite

Abstract We report on structural, chemical and low temperature magnetic properties of lead free 0.6NiFe2O4 - 0.4Na0.5Bi0.5TiO3 composite. NiFe2O4 (NFO) and Na0.5Bi0.5TiO3 (NBTO) are seen to crystallize in inverse spinel and perovskite structure respectively. 0.6NiFe2O4 - 0.4Na0.5Bi0.5TiO3 composite exhibits both NFO and NBTO phases in appropriate composition. Zero field cooled (ZFC) and field cooled (FC) magnetization measurements carried out from 15 K to 300 K shows a large bifurcation at room temperature. ZFC and FC magnetization measurement exhibit a hump at Tm ⁓ 259.5 K, indicates the possible existence of competing magnetic interactions in 0.6NiFe2O4 - 0.4Na0.5Bi0.5TiO3 composite. Saturation magnetization, remanent magnetization and coercivity values are observed to increase with decreasing the temperature. Temperature dependent saturation magnetization is fit to the Bloch’s law. Magnetocrystalline anisotropy (K1) value at various temperatures are estimated and is seen to increase from 0.23 x104 erg/cc (at 300 K) to 0.34 x104 erg/cc (at 15 K).

Synthesis, Structures and Magnetic Properties of 1D Cu(II)-NIT Radical Complex

2021 ◽  
Vol 13 (7) ◽  
pp. 1253-1258
Author(s):  
Cai-Wen Zhang ◽  
You-Juan Zhang ◽  
Jing Chen ◽  
Qing-Lun Wang
Keyword(s):  
Magnetic Properties ◽  
Single Crystal ◽  
Magnetic Interactions ◽  
X Ray Diffraction ◽  
Coordination Environment ◽  
Space Group ◽  
X Ray ◽  
Coordination Modes ◽  
Radical Complex ◽  
Ferromagnetic Interactions

ABSTRACTAn 1D Cu(II) complex, which formula is [Cu(hfac)2NITpPy]n (1) (NITpPy = 2-(4-pyridyl)-4,4,5,5-tetra-methylimidazoline-1-oxyl-3-oxide, hfac = hexafluoroacetylacetonate) has been synthesized and characterized by single crystal X-ray diffraction. The complex 1 crystallizes in the triclinic pī space group. Two adjacent Cu(II) ions with different coordination modes are bridged by NITpPy to form a magnetic zig-zag chain. In the built chains, the Cu(II) ions located in the CuO4N2 coordination environment and the >N–O–Cu(II)- O–N< hetero-spin clusters of the CuO6 units are alternately arranged, which lead to two different Cu-NITpPy magnetic interactions. The fit parameters (J1 = −3.56 cm−1 and J2 = 0.46 cm−1) indicate an antiferromagnetic and ferromagnetic interactions in the complex 1.

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