scholarly journals Preparation and performance of CuFe2O4 and ZnFe2O4 magnetic nanocrystals

2021 ◽  
Author(s):  
Q.G Jia ◽  
S.H. Liang ◽  
Q.X Wang
Keyword(s):  
Saturation Magnetization ◽  
Crystal Structures ◽  
Room Temperature ◽  
Magnetic Nanocrystals ◽  
And Performance ◽  
Spinel Structures ◽  
20 Nm

Abstract Based on the coprecipitation of FeSO4(NH4)2SO4 with CuCl2 and ZnSO4, CuFe2O4 and ZnFe2O4 nanocrystals were successfully synthesized. The morphology and the crystal structures of the nanoparticles were studied via SEM, TEM and XRD, which showed that MFe2O4 samples were formed aggregated nanoparticles with crystal sizes of 16~20 nm with a narrow dispersion in size. The samples had the typical spinel structures. Magnetic analyses demonstrated that the CuFe2O4 sample had the saturation magnetization (Ms) of 10.10 emu/g with the coercivity of 3459.39 Oe, while the ZnFe2O4 sample had the Ms of 8.27 emu/g with the coercivity of 25.42 Oe at room temperature, respectively.

scholarly journals Robust skyrmion mediated reversal of ferromagnetic nanodots of 20 nm lateral dimension with high Ms and observable DMI

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Md Mahadi Rajib ◽  
Walid Al Misba ◽  
Dhritiman Bhattacharya ◽  
Jayasimha Atulasimha
Keyword(s):  
Saturation Magnetization ◽  
Data Storage ◽  
Energy Efficient ◽  
Room Temperature ◽  
Thermal Noise ◽  
Stray Field ◽  
Lateral Dimension ◽  
Storage Devices ◽  
20 Nm ◽  
Moriya Interaction

AbstractImplementation of skyrmion based energy efficient and high-density data storage devices requires aggressive scaling of skyrmion size. Ferrimagnetic materials are considered to be a suitable platform for this purpose due to their low saturation magnetization (i.e. smaller stray field). However, this method of lowering the saturation magnetization and scaling the lateral size of skyrmions is only applicable where the skyrmions have a smaller lateral dimension compared to the hosting film. Here, we show by performing rigorous micromagnetic simulation that the size of skyrmions, which have lateral dimension comparable to their hosting nanodot can be scaled by increasing saturation magnetization. Also, when the lateral dimension of nanodot is reduced and thereby the skyrmion confined in it is downscaled, there remains a challenge in forming a stable skyrmion with experimentally observed Dzyaloshinskii–Moriya interaction (DMI) values since this interaction has to facilitate higher canting  per spin to complete a 360° rotation along the diameter. In our study, we found that skyrmions can be formed in 20 nm lateral dimension nanodots with high saturation magnetization (1.30–1.70 MA/m) and DMI values (~ 3 mJ/m2) that have been reported to date. This result could stimulate experiments on implementation of highly dense skyrmion devices. Additionally, using this, we show that voltage controlled magnetic anisotropy based switching mediated by an intermediate skyrmion state can be achieved in the soft layer of a ferromagnetic p-MTJ of lateral dimensions 20 nm with sub 1 fJ/bit energy in the presence of room temperature thermal noise with reasonable DMI ~ 3 mJ/m2.

The Structure and Magnetic Properties of NiZn-Ferrite Films Deposited by Magnetron Sputtering at Room Temperature

2013 ◽  
Vol 690-693 ◽  
pp. 1702-1706 ◽  
Author(s):  
Shuang Jun Nie ◽  
Hao Geng ◽  
Jun Bao Wang ◽  
Lai Sen Wang ◽  
Zhen Wei Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetron Sputtering ◽  
Saturation Magnetization ◽  
Room Temperature ◽  
Oxygen Flow ◽  
Flow Ratio ◽  
Study Results ◽  
Ferrite Thin Films ◽  
Ferrite Films

NiZn-ferrite thin films were deposited onto silicon and glass substrates by radio frequency magnetron sputtering at room temperature. The effects of the relative oxygen flow ratio on the structure and magnetic properties of the thin films were investigated. The study results reveal that the films deposited under higher relative oxygen flow ratio show a better crystallinity. Static magnetic measurement results indicated that the saturation magnetization of the films was greatly affected by the crystallinity, grain dimension, and cation distribution in the NiZn-ferrite films. The NiZn-ferrite thin films with a maximum saturation magnetization of 151 emucm-3, which is about 40% of the bulk NiZn ferrite, was obtained under relative oxygen flow ratio of 60%.

Distorted chiolite crystal structures of α-Na5M3F14 (M=Cr,Fe,Ga) studied by X-ray powder diffraction

2003 ◽  
Vol 18 (2) ◽  
pp. 128-134 ◽  
Author(s):  
A. Le Bail ◽  
A.-M. Mercier
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Rietveld Refinements ◽  
Space Group ◽  
X Ray ◽  
Precise Characterization

The crystal structures of the chiolite-related room temperature phases α-Na5M3F14 (MIII=Cr,Fe,Ga) are determined. For all of them, the space group is P21/n, Z=2; a=10.5096(3) Å, b=7.2253(2) Å, c=7.2713(2) Å, β=90.6753(7)° (M=Cr); a=10.4342(7) Å, b=7.3418(6) Å, c=7.4023(6) Å, β=90.799(5)° (M=Fe), and a=10.4052(1) Å, b=7.2251(1) Å, c=7.2689(1), β=90.6640(4)° (M=Ga). Rietveld refinements produce final RF factors 0.036, 0.033, and 0.035, and RWP factors, 0.125, 0.116, and 0.096, for MIII=Cr, Fe, and Ga, respectively. The MF6 polyhedra in the defective isolated perovskite-like layers deviate very few from perfect octahedra. Subtle octahedra tiltings lead to the symmetry decrease from the P4/mnc space group adopted by the Na5Al3F14 chiolite aristotype to the P21/n space group adopted by the title series. Facile twinning precluded till now the precise characterization of these compounds.

Eu3+ Ion Luminescence Spectra from Lanthanide Sesquioxides Exhibiting Three Different Crystal Structures

1992 ◽  
Vol 46 (2) ◽  
pp. 273-276 ◽  
Author(s):  
G. Chen ◽  
R. G. Haire ◽  
J. R. Peterson
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Room Temperature ◽  
Luminescence Spectra ◽  
Spectral Splitting ◽  
The Eu

We have investigated the Eu3+ ion luminescence spectra from different host crystals of the lanthanide sesquioxides exhibiting either the A, B, or C form. The Eu3+ ion luminescence spectra from B-type Eu2O3 and from Eu3+-doped A-type La2O3 and C-type Lu2O3 were obtained at room temperature. It is suggested that the luminescence from f-f transitions in the Eu3+ ion can be used to determine the crystal structure, because the different Eu3+ ion site symmetries in the different crystal structures give rise to different characteristic spectral splitting patterns.

The crystal structures of solvent-free alkali-metal squarates from powder diffraction data

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Robert E. Dinnebier ◽  
Hanne Nuss ◽  
Martin Jansen
Keyword(s):  
High Resolution ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Solvent Free ◽  
Crystallographic Data ◽  
Powder Diffraction Data ◽  
X Ray

AbstractThe crystal structures of solvent-free lithium, sodium, rubidium, and cesium squarates have been determined from high resolution synchrotron and X-ray laboratory powder patterns. Crystallographic data at room temperature of Li

Synthesis and aldol cyclotrimerization of 4,7-di-tert-butylacenaphthenone

2006 ◽  
Vol 84 (10) ◽  
pp. 1268-1272 ◽  
Author(s):  
Aaron W Amick ◽  
Keith S Griswold ◽  
Lawrence T Scott
Keyword(s):  
Key Words ◽  
Crystal Structures ◽  
Silica Gel ◽  
Room Temperature ◽  
Titanium Tetrachloride ◽  
X Ray ◽  
Synthetic Intermediates

An efficient gram scale synthesis of the previously unknown 4,7-di-tert-butylacenaphthenone (3b) is reported. The facile isomerization of epoxide 9b to ketone 3b occurs simply on stirring a solution of 9b with silica gel at room temperature. Aldol cyclotrimerization of 3b with titanium tetrachloride gives 2,5,8,11,14,17-hexa-tert-butylde cacyclene (1b) in 58% isolated yield. X-ray crystal structures have been obtained for the synthetic intermediates 4,7-di-tert-butylacenaphthene (2b) and 4,7-di-tert-butylacenaphthylene (8b).Key words: aromatic, decacyclene, hydrocarbon, nonalternant, polycyclic.

scholarly journals Supramolecular Frameworks Based on Rhenium Clusters Using the Synthons Approach

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2662
Author(s):  
Nathalie Audebrand ◽  
Antoine Demont ◽  
Racha El Osta ◽  
Yuri V. Mironov ◽  
Nikolay G. Naumov ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Crystal Structures ◽  
Ligand Exchange ◽  
Alkaline Earth ◽  
Room Temperature ◽  
Hydration Rate ◽  
Rhenium Cluster ◽  
New Compounds ◽  
Cluster Unit

The reaction of the K4[{Re6Si8}(OH)a6]·8H2O rhenium cluster salt with pyrazine (Pz) in aqueous solutions of alkaline or alkaline earth salts at 4 °C or at room temperature leads to apical ligand exchange and to the formation of five new compounds: [trans-{Re6Si8}(Pz)a2(OH)a2(H2O)a2] (1), [cis-{Re6Si8}(Pz)a2(OH)a2(H2O)a2] (2), (NO3)[cis-{Re6Si8}(Pz)a2(OH)a(H2O)a3](Pz)·3H2O (3), [Mg(H2O)6]0.5[cis-{Re6Si8}(Pz)a2(OH)a3(H2O)a]·8.5H2O (4), and K[cis-{Re6Si8}(Pz)a2(OH)a3(H2O)a]·8H2O (5). Their crystal structures are built up from trans- or cis-[{Re6Si8}(Pz)a2(OH)a4−x(H2O)ax]x−2 cluster units. The cohesions of the 3D supramolecular frameworks are based on stacking and H bonding, as well as on H3O2−bridges in the cases of (1), (2), (4), and (5) compounds, while (3) is built from stacking and H bonding only. This evidences that the nature of the synthons governing the cluster unit assembly is dependent on the hydration rate of the unit.

scholarly journals MINIMAL VARIATION OF DEFECT STRUCTURE DUE TO THE ORDER OF ROOM TEMPERATURE HYDROGEN ISOTOPE IMPLANTATION AND SELF-ION IRRADIATION IN NICKEL

MRS Advances ◽  
2016 ◽  
Vol 1 (42) ◽  
pp. 2887-2892
Author(s):  
Brittany Muntifering ◽  
Jianmin Qu ◽  
Khalid Hattar
Keyword(s):  
Dislocation Loop ◽  
Hydrogen Isotope ◽  
Room Temperature ◽  
Ion Irradiation ◽  
In Situ Tem ◽  
Loop Formation ◽  
Radiation Induced ◽  
Formation And Evolution ◽  
And Performance ◽  
Induced Defects

ABSTRACTThe formation and stability of radiation-induced defects in structural materials in reactor environments significantly effects their integrity and performance. Hydrogen, which may be present in significant quantities in future reactors, may play an important role in defect evolution. To characterize the effect of hydrogen on cascade damage evolution, in-situ TEM self-ion irradiation and deuterium implantation was performed, both sequentially and concurrently, on nickel. This paper presents preliminary results characterizing dislocation loop formation and evolution during room temperature deuterium implantation and self-ion irradiation and the consequence of the sequence of irradiation. Hydrogen isotope implantation at room temperature appears to have little or no effect on the final dislocation loop structures that result from self-ion irradiation, regardless of the sequence of irradiation. Tilting experiments emphasize the importance of precise two-beam conditions for characterizing defect size and structure.

scholarly journals Impurity-Induced Spin-State Crossover in La0.8Sr0.2Co1−xAlxO3

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 411 ◽  
Author(s):  
Ichiro Terasaki ◽  
Masamichi Ikuta ◽  
Takafumi Yamamoto ◽  
Hiroki Taniguchi
Keyword(s):  
Magnetic Field ◽  
Saturation Magnetization ◽  
Spin State ◽  
Room Temperature ◽  
Significant Fraction ◽  
Al Substitution ◽  
Spin Number ◽  
Average Spin ◽  
Heikes Formula ◽  
Temperature Susceptibility

We have prepared a set of polycrystalline samples of La 0.8 Sr 0.2 Co 1 − x Al x O 3 ( 0 ≤ x ≤ 0.2 ), and have measured the magnetization as functions of temperature and magnetic field. We find that the average spin number per Co ion ( S Co ) evaluated from the room-temperature susceptibility is around 1.2–1.3 and independent of x. However, we further find that S Co evaluated from the saturation magnetization at 2 K is around 0.3–0.7, and decreases dramatically with x. This naturally indicates that a significant fraction of the Co 3 + ions experience a spin-state crossover from the intermediate- to low-spin state with decreasing temperature in the Al-substituted samples. This spin-state crossover also explains the resistivity and the thermopower consistently. In particular, we find that the thermopower is anomalously enhanced by the Al substitution, which can be consistently explained in terms of an extended Heikes formula.

Sign in / Sign up

Export Citation Format

Share Document