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.

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.

NOVEL BINARY SPIN GLASS ALLOYS SYNTHESIZED BY MECHANICAL MILLING

1995 ◽  
Vol 09 (03n04) ◽  
pp. 145-162 ◽  
Author(s):  
G. F. ZHOU ◽  
H. BAKKER
Keyword(s):  
Spin Glass ◽  
Mechanical Milling ◽  
Spin Glasses ◽  
Ac Susceptibility ◽  
Freezing Temperature ◽  
High Energy ◽  
Zero Field ◽  
High Concentration ◽  
Freezing Temperatures ◽  
Field Cooling

A few novel binary spin glass alloys have been successfully synthesized by mechanical milling of ordered intermetallic compounds in a high energy ball mill. These alloys are amorphous Co 2 Ge , atomically disordered crystalline GdAl 2, and ball-milled crystalline and amorphous CoZr. The characteristic features of spin glasses are observed; these are (a) the sharp cusps at the freezing temperature T f in both ac and dc magnetic susceptibility versus temperature curves and their peculiar sensitivity to the external magnetic field; (b) the irreversibility, i.e. the difference in value and shape between the magnetisation versus temperature curves after zero field cooling (ZFC) and field cooling (FC) at temperatures below T f and (c) the displacement of the FC magnetisation curve relative to ZFC curve and the corresponding remanence in the FC curve at low temperatures. The freezing temperatures are 41, 65, 35, and 11 K, respectively, which are defined by the sharp cusps in the lowest field ac susceptibility versus temperature curves. The freezing temperatures are lowered with increasing external field. The common feature of these materials is that all are binary alloys with a rather high concentration of the magnetic component. The discovery of these novel spin glasses is of significance because they not only represent new classes of spin glass materials but also demonstrate the use of mechanical milling as a novel technique to synthesize various new materials such as spin glasses. The results are reviewed briefly.

scholarly journals Effects of Non-Stoichiometry on the Ground State of the Frustrated System Li0.8Ni0.6Sb0.4O2

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6785
Author(s):  
Evgeniya Vavilova ◽  
Timur Salikhov ◽  
Margarita Iakovleva ◽  
Tatyana Vasilchikova ◽  
Elena Zvereva ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Specific Heat ◽  
Spin Glass ◽  
Short Range ◽  
Freezing Temperature ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
7Li Nmr

The non-stoichiometric system Li0.8Ni0.6Sb0.4O2 is a Li-deficient derivative of the zigzag honeycomb antiferromagnet Li3Ni2SbO6. Structural and magnetic properties of Li0.8Ni0.6Sb0.4O2 were studied by means of X-ray diffraction, magnetic susceptibility, specific heat, and nuclear magnetic resonance measurements. Powder X-ray diffraction data shows the formation of a new phase, which is Sb-enriched and Li-deficient with respect to the structurally honeycomb-ordered Li3Ni2SbO6. This structural modification manifests in a drastic change of the magnetic properties in comparison to the stoichiometric partner. Bulk static (dc) magnetic susceptibility measurements show an overall antiferromagnetic interaction (Θ = −4 K) between Ni2+ spins (S = 1), while dynamic (ac) susceptibility reveals a transition into a spin glass state at a freezing temperature TSG ~ 8 K. These results were supported by the absence of the λ-anomaly in the specific heat Cp(T) down to 2 K. Moreover, combination of the bulk static susceptibility, heat capacity and 7Li NMR studies indicates a complicated temperature transformation of the magnetic system. We observe a development of a cluster spin glass, where the Ising-like Ni2+ magnetic moments demonstrate a 2D correlated slow short-range dynamics already at 12 K, whereas the formation of 3D short range static ordered clusters occurs far below the spin-glass freezing temperature at T ~ 4 K as it can be seen from the 7Li NMR spectrum.

Magnetic properties of nanoparticles

2017 ◽  
Author(s):  
Steen Mørup ◽  
Cathrine Frandsen ◽  
Mikkel F. Hansen
Keyword(s):  
Magnetic Properties ◽  
Ac Susceptibility ◽  
Magnetic Moments ◽  
Magnetic Interactions ◽  
Blocking Temperature ◽  
Magnetic Phase Transitions ◽  
Magnetic Domains ◽  
Superparamagnetic Relaxation ◽  
Magnetic Dynamics ◽  
Structure Of Nanoparticles

This article discusses the magnetic properties of nanoparticles. It first considers magnetic domains and the critical size for single-domain behavior of magnetic nanoparticles before providing an overview of magnetic anisotropy in nanoparticles. It then examines magnetic dynamics in nanoparticles, with particular emphasis on superparamagnetic relaxation and the use of Mössbauer spectroscopy, dc magnetization measurements, and ac susceptibility measurements for studies of superparamagnetic relaxation. It also describes magnetic dynamics below the blocking temperature, magnetic interactions between nanoparticles, and fluctuations of the magnetization directions. Finally, it analyzes the magnetic structure of nanoparticles, focusing on magnetic phase transitions and surface effects, non-collinear spin structures, and magnetic moments of antiferromagnetic nanoparticles.

scholarly journals Preparation and Magnetic Properties of ZnFe2O4Nanotubes

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Yan Xu ◽  
Yantian Liang ◽  
Lijuan Jiang ◽  
Huarui Wu ◽  
Hongzhi Zhao ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Sol Gel ◽  
Anodic Aluminum Oxide Template ◽  
Blocking Temperature ◽  
Outer Diameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anodic Aluminum ◽  
Transmission Electron

Ordered ZnFe2O4nanotube arrays with the average outer diameter of 100 nm were prepared in porous anodic aluminum oxide template using an improved sol-gel approach. The morphology was studied by transmission electron and field emission scanning electron microscope. X-ray diffraction result shows that the nanotubes were polycrystalline in structure. The magnetic properties of the prepared ZnFe2O4nanotubes were also studied. The results show that the sample shows typical superparamagnetism at room temperature and obvious ferromagnetism below blocking temperature.

Static and Dynamic Magnetic Properties of Co Nanoparticles

2008 ◽  
Vol 8 (8) ◽  
pp. 4086-4091 ◽  
Author(s):  
S. Srinath ◽  
P. Poddar ◽  
Deepti S. Sidhaye ◽  
B. L. V. Prasad ◽  
J. Gass ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Ac Susceptibility ◽  
Wide Distribution ◽  
Superparamagnetic Nanoparticles ◽  
Blocking Temperature ◽  
Zero Field ◽  
Relaxation Effects ◽  
Spin Disorder ◽  
Co Nanoparticles

Co nanoparticles have been synthesized using wet-chemical methods. As-synthesized particles show a sharp low temperature peak in zero-field cooled (ZFC) magnetization well below the blocking transition temperature and this feature is associated with surface spin disorder. We have investigated the dynamic magnetic properties of Co using ac susceptibility and resonant RF transverse susceptibility (TS). We also studied the memory and relaxation effects in these nanoparticle systems. From these measurements we show a typical blocking behavior of an assembly of superparamagnetic nanoparticles with a wide distribution of blocking temperatures. The transverse susceptibility measurements on these particles show the presence of anisotropy even above the blocking temperature. The role of surface anisotropy and the size distribution of the particles on the observed memory and magnetic relaxation effects are discussed.

Structure and Magnetism of Nanocrystalline KδMnO2

1999 ◽  
Vol 602 ◽  
Author(s):  
R.M. Stroud ◽  
E. Carpenter ◽  
V.M. Browning ◽  
J.W. Long ◽  
K.E. Swider ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Sol Gel ◽  
Blocking Temperature ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
Mixed Valency ◽  
Transmission Electron ◽  
Typical Particle ◽  
20 Nm

AbstractThe structure and magnetic properties of sol-gel-synthesized, nanocrystalline KσMnO2 were investigated. The nanoparticles were determined by x-ray diffraction and high-resolution transmission electron microscopy to be single-crystal rods of the cryptomelane phase of MnO2, with a typical particle size of 6 nm × 20 nm. The field and temperature dependence of the magnetization indicates superparamagnetic behavior, with a blocking temperature of 15K. The dependence of the magnetic properties on particle size, surface layers and mixed valency is discussed.

scholarly journals Observation of Spin-Glass Behavior in Spinel Compound CoGa2O4

2021 ◽  
Author(s):  
Jiyu Hu ◽  
Yongqing Ma ◽  
Xucai Kan ◽  
Chaocheng Liu
Keyword(s):  
Spin Glass ◽  
Ac Susceptibility ◽  
Freezing Temperature ◽  
Peak Shift ◽  
Synthesis Process ◽  
Zero Field ◽  
Magnetic Frustration ◽  
Dynamical Exponent ◽  
Spin Glass Behavior ◽  
Fitting Parameters

Abstract In this work, the synthesis process, crystal-structure, and comprehensive physical properties of spinel compound CoGa2O4 have been investigated. The competition between antiferromagnetism (AFM) and ferromagnetism (FM) are considered to be the crucial elements for resulting in spin-glass (SG) behavior due to magnetic frustration. The observed SG behavior is determined by the temperature dependence of magnetization M(T) curves under the ZFC (zero-field-cooled) and FCC (field-cooled) processes, where form the intense irreversibility divergence. Moreover, the corresponding fitting parameters (the freezing temperature T0 = 9.32 K, the flipping time τ0 = 4.49 × 10-10 s, and the dynamical exponent zν = 4.46) strongly indicate the existence of the SG behavior. Meanwhile, as another specific characteristic for SG, in our present work, frequency (f) and magnetic field (H) have a strong influence on the peaks of AC susceptibility. From where, with the increase of f and H, the freezing temperature follows a corresponding peak shift. All the above phenomena and relevant analyses of magnetic frustration behavior confirm the typical SG behavior in CoGa2O4 system.

Magnetic Properties Of Tdae-C60: Remanence and Relaxation

1995 ◽  
Vol 413 ◽  
Author(s):  
M. Tokumoto ◽  
Y. S. Song ◽  
K. Tanaka ◽  
T. Sato ◽  
T. Yamabe
Keyword(s):  
Magnetic Properties ◽  
Temperature Dependence ◽  
Spin Glass ◽  
Ground State ◽  
Freezing Temperature ◽  
Squid Magnetometer ◽  
Zero Field ◽  
Relaxation Phenomena ◽  
Magnetic Ground State ◽  
Low Field

ABSTRACTPrecise measurements of low-field magnetization of TDAE-C60 (TDAE; tetrakis(dimethylamino)ethylene) by SQUID magnetometer revealed a clear “remanence” or “irreversibility”, i.e. difference in the temperature dependence between zero-field cooled (ZFC) and field cooled (FC) conditions below the freezing temperature Tf around 10 K. Also, an extremely slow relaxation phenomena of magnetization was observed. These “glassy” characteristics are reminiscent of a “spin-glass” with Tf at about 10 K as the nature of the magnetic ground state of TDAE-C60.

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.

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