scholarly journals Unidirectional Magnetic Anisotropy in Dense Vertically-Standing Arrays of Passivated Nickel Nanotubes

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2444
Author(s):  
Claudiu Locovei ◽  
Nicolae Filipoiu ◽  
Andrei Kuncser ◽  
Anda-Elena Stanciu ◽  
Ştefan Antohe ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Low Cost ◽  
Magnetic Behavior ◽  
Fine Tuning ◽  
Geometrical Parameters ◽  
Micromagnetic Simulations ◽  
Electrochemical Growth ◽  
Si Substrates ◽  
Unidirectional Anisotropy

We report the facile and low-cost preparation as well as detailed characterization of dense arrays of passivated ferromagnetic nickel (Ni) nanotubes (NTs) vertically-supported onto solid Au-coated Si substrates. The proposed fabrication method relies on electrochemical synthesis within the nanopores of a supported anodic aluminum oxide (AAO) template and allows for fine tuning of the NTs ferromagnetic walls just by changing the cathodic reduction potential during the nanostructures’ electrochemical growth. Subsequently, the experimental platform allowed further passivation of the Ni NTs with the formation of ultra-thin antiferromagnetic layers of nickel oxide (NiO). Using adequately adapted magnetic measurements, we afterwards demonstrated that the thickness of the NT walls and of the thin antiferromagneticNiO layer, strongly influences the magnetic behavior of the dense array of exchange-coupled Ni/NiO NTs. The specific magnetic properties of these hybrid ferromagnetic/antiferromagnetic nanosystems were then correlated with the morpho-structural and geometrical parameters of the NTs, as well as ultimately strengthened by additionally-implemented micromagnetic simulations. The effect of the unidirectional anisotropy strongly amplified by the cylindrical geometry of the ferromagnetic/antiferromagnetic interfaces has been investigated with the magnetic field applied both parallel and perpendicular to the NTs axis.

Synthesis and Characterization of PEG-Modified ZnGd0.1Fe1.9O4 Ferrite Nanoparticles for Interstitial Hyperthermia to Tumor

2007 ◽  
Vol 334-335 ◽  
pp. 1209-1212
Author(s):  
Ai Hua Yao ◽  
De Ping Wang ◽  
Wen Hai Huang
Keyword(s):  
Magnetic Properties ◽  
Remanent Magnetization ◽  
Magnetic Measurements ◽  
Magnetic Behavior ◽  
Ferrite Nanoparticles ◽  
Slight Reduction ◽  
Interstitial Hyperthermia ◽  
Coprecipitation Process ◽  
Good Biocompatibility

PEG-modified ZnGd0.1Fe1.9O4 ferrite nanoparticles were synthesized by a coprecipitation process combined with a microemulsion technique. The effect of modification on the structure, magnetic properties of ZnGd0.1Fe1.9O4 nanoparticles was also investigated by XRD, FTIR, TEM and VSM. The results showed immobilizing PEG on the surfaces of magnetic nanoparticles effectively improved their dispersibility. Magnetic measurements indicated that the as-prepared PEG-modified nanoparticles exhibited relatively high magnetic properties, although a slight reduction in saturation and remanent magnetization were observed compared with unmodified samples. Therefore, with promising high magnetic behavior and potentially good biocompatibility, PEG-modified ZnGd0.1Fe1.9O4 ferrite nanoparticles would be feasible as thermoseeds for interstitial hyperthermia to tumor.

Combinatorial Synthesis and Characterization of CoMnGe Alloys

2001 ◽  
Vol 700 ◽  
Author(s):  
Frank Tsui ◽  
Liang He ◽  
Lei Ma
Keyword(s):  
Structural Evolution ◽  
Magnetic Behavior ◽  
High Energy ◽  
Ternary Alloys ◽  
Si Substrates ◽  
Transport Studies ◽  
Time Scanning ◽  
High Spin Polarization ◽  
Spin Electronic

AbstractTernary alloys of CoMnGe have been synthesized and characterized using combinatorial molecular beam epitaxy techniques. Structural evolution was studied using real-time scanning reflection high-energy electron diffraction, and magnetic properties were probed using magnetooptic Kerr effect imaging and SQUID magnetometry. Growth and properties on several substrate orientations were explored. These alloys exhibit a rich variety of magnetic and magnetooptic behavior, including a robust phase near Co2MnGe with high spin polarization, Tc, and magnetooptic response. The observed magnetic responses show strong correlation with structural transformations, such that structural ordering leads to enhanced magnetism. The observed magnetic behavior and the alloys’ compatibility with Ge and Si substrates make them potential candidates for spin electronic transport studies and applications.

scholarly journals H-Bonds, π-Stacking and (Water)O-H/π Interactions in (µ4-EDTA)Bis(Imidazole) Dicopper(II) Dihydrate

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 48
Author(s):  
Jeannette Carolina Belmont-Sánchez ◽  
María Eugenia García-Rubiño ◽  
Antonio Frontera ◽  
Josefa María González-Pérez ◽  
Alfonso Castiñeiras ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Magnetic Behavior ◽  
Esr Spectra ◽  
Water Molecules ◽  
Polymeric Compound ◽  
Π Stacking ◽  
Carboxylate Groups ◽  
3D Network ◽  
Ft Ir

We synthesized and studied the polymeric compound {[Cu2(µ4-EDTA)(Him)2] 2H2O}n (1). The single-crystal structure is reported along with an in depth characterization of its thermal stability (TGA), spectral properties (FT-IR, Vis-UV and RSE), and magnetic behavior. The crystal consists of infinite 2D-networks built by centrosymmetric dinuclear motifs, constructed by means of a bridging anti,syn-carboxylate group from each asymmetric unit. Each layer guides Him ligands toward their external faces. They are connected by intermolecular (Him)N-H···O(carboxylate) bonds and antiparallel π–π stacking between symmetry related pairs of Him ligands, and then pillared in a 3D-network with parallel channels, where disordered water molecules are guested. About half of the labile water is lost from these channels over a wide temperature range (r.t. to 210 °C) before the other one, most strongly retained by the cooperating action of (water)O1-H(1A)···O(carboxylate) and (water) O1-H(1B)···π(Him) interactions. The latter is lost when organic ligands start to burn. ESR spectra and magnetic measurements indicated that symmetry related Cu(II) centers connected by the bridging carboxylate groups behave magnetically not equivalently, enabling an exchange interaction larger than their individual Zeeman energies.

scholarly journals Environmental magnetism: Application to cave sediments

2017 ◽  
Vol 47 (2) ◽  
pp. 892 ◽  
Author(s):  
E. Aidona ◽  
S. Pechlivanidou ◽  
Ch. Pennos
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Measurements ◽  
Low Cost ◽  
Environmental Magnetism ◽  
Northern Greece ◽  
Cave Sediments ◽  
Wide Range ◽  
Sediment Records ◽  
Archaeological Artifacts

Environmental magnetism techniques allow a rapid, low cost and sensitive characterization of sediments and can be applied in a wide range of environments. More specific, magnetic properties can be successfully used to reconstruct paleoenvironmental and paleoclimatic conditions in rockshelter and cave sites. Cave sediments, imprint the environmental conditions at the Earth’s surface at the time of deposition since are well protected both at the interior and at the entrance of the cave systems. In addition, many cultural sequences and archaeological artifacts are well preserved in rockshelter and cave sediment records and can be effectively used for paleoenvironmental interpretations. In this study we present data from two different cave sites from Northern Greece. In the first cave (Maronia Cave) magnetic measurements were performed in two cores 80 and 90 cm, respectively, located inside the cave area. High values of magnetic susceptibility are directly linked with the human activity inside the cave, while lower values show deposition under infiltration and fluvial processes. In the second cave (Mikro Eptamilon Cave), magnetic susceptibility and frequency dependent magnetic susceptibility depicted from a sedimentary sequence with a thickness of 200 cm, located in the entrance of the cave. Results lead to conclusions concerning the velocity of the paleo-flow likely related to the paleoclimatic conditions that dominated the broader area.

Studying the Temperature Effect on the Magnetic Behavior of Fe3O4 Water Based Ferrofluid

2017 ◽  
Vol 744 ◽  
pp. 468-472
Author(s):  
Ahmad Amirabadizadeh ◽  
Amir Zelati ◽  
Zahra Lotfollahi
Keyword(s):  
Magnetic Measurements ◽  
Spherical Shape ◽  
Magnetic Behavior ◽  
Precipitation Method ◽  
Magnetite Nanoparticle ◽  
Water Based ◽  
Magnetic Softness ◽  
Co Precipitation ◽  
Average Size

In this study, Iron Oxide (Fe3O4) nanoparticles water based ferrofluid, was synthesized by co-precipitation method. XRD was used to study the structural characterization of the sample and to measure the size of the crystallites (using Scherrer equation). TEM was utilized to examine the shape, the size distribution and the morphology of the nanoparticles. VSM was carried out to measure the magnetic properties (like Mr, Ms and Hc) of the Fe3O4 (magnetite) nanoparticle and magnetite ferrofluid at 80 and 300 K. The results indicate that the average size of the magnetite roughly spherical shape nanoparticles is 13nm. The VSM results show that the magnetite ferrofluid contains single domain magnetic nanoparticles with superparamagnetic behavior. In addition, the magnetic measurements demonstrate that with decreasing the temperature of the ferrofluid, its magnetic softness decreases while its anisotropy increases.

Electron microscope characterization of MOCVD-grown gap layers on Si

1986 ◽  
Vol 44 ◽  
pp. 724-725
Author(s):  
K.M. Jones ◽  
M.M. Al-Jassim ◽  
J.M. Olson
Keyword(s):  
Atmospheric Pressure ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Organic Chemical ◽  
Lattice Match ◽  
Si Substrates ◽  
Metal Organic ◽  
Good Lattice ◽  
Antiphase Domains

The epitaxial growth of III-V semiconductors on Si for integrated optoelectronic applications is currently of great interest. GaP, with a lattice constant close to that of Si, is an attractive buffer between Si and, for example, GaAsP. In spite of the good lattice match, the growth of device quality GaP on Si is not without difficulty. The formation of antiphase domains, the difficulty in cleaning the Si substrates prior to growth, and the poor layer morphology are some of the problems encountered. In this work, the structural perfection of GaP layers was investigated as a function of several process variables including growth rate and temperature, and Si substrate orientation. The GaP layers were grown in an atmospheric pressure metal organic chemical vapour deposition (MOCVD) system using trimethylgallium and phosphine in H2. The Si substrates orientations used were (100), 2° off (100) towards (110), (111) and (211).

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

scholarly journals Microstructure and Thermoelectric Properties of (Bi0.48Sb1.52)Te3 Thick Films Prepared with Tape Casting Method

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 140
Author(s):  
Lichen Liu ◽  
Ziping Cao ◽  
Min Chen ◽  
Jun Jiang
Keyword(s):  
Thermoelectric Properties ◽  
Low Cost ◽  
Thick Films ◽  
Tape Casting ◽  
Casting Process ◽  
Casting Method ◽  
Glass Substrates ◽  
Conductive Films ◽  
Casting Technology

This paper reports the fabrication and characterization of (Bi0.48Sb1.52)Te3 thick films using a tape casting process on glass substrates. A slurry of thermoelectric (Bi0.48Sb1.52)Te3 was developed and cured thick films were annealed in a vacuum chamber at 500–600 °C. The microstructure of these films was analyzed, and the Seebeck coefficient and electric conductivity were tested. It was found that the subsequent annealing process must be carefully designed to achieve good thermoelectric properties of these samples. Conductive films were obtained after annealing and led to acceptable thermoelectric performance. While the properties of these initial materials are not at the level of bulk materials, this work demonstrates that the low-cost tape casting technology is promising for fabricating thermoelectric modules for energy conversion.

scholarly journals Multi-Camera Based Setup for Geometrical Measurement of Free-Falling Molten Glass Gob

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1041
Author(s):  
Mazhar Hussain ◽  
Mattias O’Nils ◽  
Jan Lundgren
Keyword(s):  
Free Fall ◽  
Frame Rate ◽  
Geometrical Parameters ◽  
Contactless Method ◽  
Molten Material ◽  
Dynamic Changes ◽  
Direct Measurements ◽  
Molten Materials ◽  
Free Falling

High temperatures complicate the direct measurements needed for continuous characterization of the properties of molten materials such as glass. However, the assumption that geometrical changes when the molten material is in free-fall can be correlated with material characteristics such as viscosity opens the door to a highly accurate contactless method characterizing small dynamic changes. This paper proposes multi-camera setup to achieve accuracy close to the segmentation error associated with the resolution of the images. The experimental setup presented shows that the geometrical parameters can be characterized dynamically through the whole free-fall process at a frame rate of 600 frames per second. The results achieved show the proposed multi-camera setup is suitable for estimating the length of free-falling molten objects.

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