scholarly journals Annealing effects on the magnetic properties of highly-packed vertically-aligned nickel nanotubes

RSC Advances ◽  
2017 ◽  
Vol 7 (30) ◽  
pp. 18609-18616 ◽  
Author(s):  
Vlad-Andrei Antohe ◽  
Emeline Nysten ◽  
Juan Manuel Martínez-Huerta ◽  
Pedro Miguel Pereira de Sá ◽  
Luc Piraux

Hysteresis loops showing the decrease of the saturation magnetic moment (left) through a dense array of vertically-aligned Ni nanotubes after their progressive thermal conversion into hybrid ferromagnetic/antiferromagnetic Ni/NiO nanotubes (right).


2018 ◽  
Vol 185 ◽  
pp. 03005
Author(s):  
Anatoly B. Rinkevich ◽  
Alexander V. Korolev ◽  
Mikhail I. Samoilovich ◽  
Sergej O. Demokritov ◽  
Dmitry V. Perov

Magnetic properties of the nanocomposite materials containing particles of rare earth titanates with pyrochlore structure have been investigated. For the nanocomposites with Gd2Ti2O7, La2Ti2O7 it has been observed that the effective magnetic moment in the nanocomposites differs substantially from that for Gd3+ and La3+ ions. The hysteresis loops was obtained for the nanocomposites with Dy3+, Gd3+, Yb3+, Er+, Sm3+ ions. There is no hysteresis loops for the nanocomposites with La2Ti2O7, Pr2Ti2O7 and Nd2Ti2O7 particles. It has been shown that nanocomposites with Yb2Ti2O7, Dy2Ti2O7 and Er2Ti2O7 particles have one crossing point on the descending branches of hysteresis loop in some temperature range.



1998 ◽  
Vol 540 ◽  
Author(s):  
M. Sorescu

AbstractNd:YAG laser (λ,=532 nm, τ=8 ns, Φ =30 J/cm2, v=10 Hz) induced transformations in Fe81B135Si35C2metallic glass were characterized by transmission and conversion electron Mossbauer spectroscopy, hysteresis loops and ac susceptibility measurements. The radiation-driven changes were further compared with alpha particle beam irradiation effects (W=2.8 MeV, Φ=1016and 1017 cm−2) in the same amorphous material. Pulsed laser irradiation of Fe81B135Si3.5C2 metallic glass was found to induce magnetic anisotropy, surface oxidation, onset of crystallization, slight increase in the saturation magnetic moment and changes in the imaginary susceptibility component. Alpha particle beam irradiation of Fe81B13.5Si3.5C2 metallic glass caused partial crystallization of the bulk of the specimen, total crystallization of the surface, as well as dose-dependent changes in the saturation magnetic moment, hysteresis and real susceptibility component.



Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3860
Author(s):  
Chen Cheng ◽  
Jianfeng Dai ◽  
Zengpeng Li ◽  
Wei Feng

The morphology of magnetic materials has a great influence on the properties, which is attributed to the magnetic anisotropy of the materials. Therefore, it is worth studying the fabrication of the aligned fiber and the change of its domain distribution. Nanoparticles and nanofibers were prepared by the hydrothermal and electrospinning methods, respectively. At the same time, the arranged nanofibers were collected by the drum collecting device. After the same annealing at 700 °C, it was found that the diameter of fibers collected by different collecting drums is similar. By studying the hysteresis loops of nanoarrays, it was found that they had strong anisotropy. The easy axis was parallel to the long axis, the Hc and Mr of the easy axis and the hard axis were 1330.5 Oe, 32.39 Am2/kg, and 857.2 Oe, 24.8 Am2/kg, respectively. Due to the anisotropy of the shape and the interaction between the particles, the Hc could not be enhanced. Therefore, the Ms and Hc of the nanoparticles were 80.23 Am2/kg and 979.3 Oe, respectively. The hysteresis loop and the change of magnetic moment during the demagnetization of the CoFe2O4 nanofiber array were simulated via micromagnetic software. The simulated Hc was 1480 Oe, which was similar to the experimental value.



2008 ◽  
Vol 22 (01n02) ◽  
pp. 63-69 ◽  
Author(s):  
J. S. PAN ◽  
J. W. CHAI ◽  
S. J. WANG ◽  
J. G. TAO ◽  
C. H. A. HUAN

The annealing effects on the composition, structure and magnetism for Co overlayer deposited onto rutile TiO 2 (100) surfaces at room temperature has been investigated. Room temperature ferromagnetic behaviour is exhibited for all samples, but saturation magnetic moment per Co atom decreases with increasing annealing temperature until 530°C. In-situ photoemission studies show that the reduction of the saturation magnetic moment is due to Co oxidation at high annealing temperature. However, the saturation magnetic moment increases after annealing the sample up to 700°C. The formation of a Co - Ti - O phase rather than Co metallic clusters observed by high-resolution transmission electron microscopy is suggested to be responsible for the increase of the saturation magnetic moment.



2016 ◽  
Vol 257 ◽  
pp. 76-80 ◽  
Author(s):  
Anna Bajorek ◽  
Clément Berger ◽  
Krystian Prusik ◽  
Marcin Wojtyniak ◽  
Grażyna Chełkowska

The morphology and magnetic properties of the Ho(Ni0.8Co0.2)­3 crystalline and ball – milled intermetallic compounds are presented. The polycrystalline bulk compound crystallizes in the rhombohedral PuNi3 - type of crystal structure and indicates ferrimagnetic arrangement with the Curie temperature of TC = 48 ± 1 K, the helimagnetic temperature Th = 26 ± 2 K with the total saturation magnetic moment of 7.78 µB/f.u. at 2 K. The use of the HEBM method leads to the formation of nanoflakes with typical thickness of less than 100 nm. The extended milling leads to the reduction in particles/crystallites size and in the emergence of the relatively small coercivity (HC).



2020 ◽  
pp. 114-119

Experimental and theoretical study Porphyrin-grafted ZnO nanowire arrays were investigated for organic/inorganic hybrid solar cell applications. Two types of porphyrin – Tetra (4-carboxyphenyle) TCPP and meso-Tetraphenylporphine (Zinc-TPP)were used to modify the nanowire surfaces. The vertically aligned nanowires with porphyrin modifications were embedded in graphene-enriched poly (3-hexylthiophene) [G-P3HT] for p-n junction nanowire solar cells. Surface grafting of ZnO nanowires was found to improve the solar cell efficiency. There are different effect for the two types of porphyrin as results of Zn existing. Annealing effects on the solar cell performance were investigated by heating the devices up to 225 °C in air. It was found that the cell performance was significantly degraded after annealing. The degradation was attributed to the polymer structural change at high temperature as evidenced by electrochemical impedance spectroscopy measurements.



2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nara Lee ◽  
Jong Hyuk Kim ◽  
Dong Gun Oh ◽  
Hyun Jun Shin ◽  
Hwan Young Choi ◽  
...  

AbstractMagnetic properties can be manipulated to enhance certain functionalities by tuning different material processing parameters. Here, we present the controllable magnetization steps of hysteresis loops in double-perovskite single crystals of Eu2CoMnO6. Ferromagnetic order emerges below TC ≈ 122 K along the crystallographic c axis. The difficulty in altering Co2+ and Mn4+ ions naturally induces additional antiferromagnetic clusters in this system. Annealing the crystals in different gas environments modifies the mixed magnetic state, and results in the retardation (after O2-annealing) and bifurcation (after Ar-annealing) of the magnetization steps of isothermal magnetization. This remarkable variation offers an efficient approach for improving the magnetic properties of double-perovskite oxides.



2006 ◽  
Vol 05 (04n05) ◽  
pp. 627-631 ◽  
Author(s):  
M. J. SUN ◽  
G. P. ZHAO ◽  
J. LIANG ◽  
G. ZHOU ◽  
H. S. LIM ◽  
...  

A simplified micromagnetic model has been proposed to calculate the hysteresis loops of nanostructured permanent magnets for various configurations, including thin films, exchange-coupled double-layer systems and bulk materials. The reversal part of the hysteresis is based on the Stoner–Wohlfarth coherent rotational model and the coercivity mechanism is due mainly to the motion of the transition region (a domain wall like magnetic moment distribution in the grain boundary). The elements of nucleation and pinning models are also incorporated.





2002 ◽  
Vol 320 (1-4) ◽  
pp. 206-209 ◽  
Author(s):  
M.Vasquez Mansilla ◽  
R Zysler ◽  
D Fiorani ◽  
L Suber


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