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991.
A. Ballestar A. SetzerP. Esquinazi N. García 《Journal of magnetism and magnetic materials》2011,323(6):758-762
We have measured the magnetization of bulk samples of highly oriented pyrolytic graphite (HOPG) at magnetic fields applied parallel and perpendicular to the graphene layers. Within experimental error the intrinsic ferromagnetic signals of the samples show similar magnetic moments at saturation for the two magnetic field directions, in contrast to recently published data (J. ?ervenka et al., Nat. Phys. 5 (2009) 840). To check that the SQUID device provides correctly the small ferromagnetic signals obtained after subtracting the 100 times larger diamagnetic background, we have prepared a sample with a superconducting Pb-film deposited on one of the HOPG surfaces. We show that the field dependence of the measured magnetic moment and after the background subtraction is highly reliable even in the sub-μ emu range providing the real magnetic properties of the embedded small ferromagnetic and superconducting signals. 相似文献
992.
Toyohisa Fujita Hyun-Seo ParkKenji Ono Seiji MatsuoKatsunori Okaya Gjergj Dodbiba 《Journal of magnetism and magnetic materials》2011,323(10):1207-1210
In this work, a temperature sensitive functional fluid was synthesized, and then its movement under the influence of magnetic field was investigated. Silica coated FeNbVB particles, prepared by chemical synthesis, were dispersed into liquid gallium, because they have a relatively high magnetization and a high temperature dependency. The synthesized functional fluid (solid fraction of 0.3 mass%) showed temperature dependence for magnetization within the testing temperature range between 298 and 353 K. The movement of gallium based fluid under the influence of the magnetic field with a magnetic field gradient was observed at various temperatures. We found that at 318 K, fluid displacement of the synthesized functional fluid is better when compared with the fluid displacement at 348 K. 相似文献
993.
Anisotropic Sm-Fe-N bulk magnets were produced by the compression shearing method using a hardened steel plate and a tungsten-carbide (WC) plate. It was found that the magnets retained the original Sm2Fe17N3 phase structure without any appreciable decomposition of the Sm2Fe17N3 phase. The anisotropic Sm-Fe-N bulk magnet produced using a WC plate had a higher density and higher crystallographic alignment of the Sm2Fe17N3 phase than that produced using a hardened steel plate, and exhibited high maximum energy products of 228 kJ/m3 with a high coercivity of 0.88 MA/m. 相似文献
994.
P. Saravanan G. Venkata RamanaK. Srinivasa Rao B. SreedharV.T.P. Vinod V. Chandrasekaran 《Journal of magnetism and magnetic materials》2011,323(15):2083-2089
Self-assembled Sm-Co nanoparticles in the form of spherical aggregates (referred as nanospheres) with diameter ranging from 50 to 180 nm were achieved by means of polyol technique. The size distribution of the Sm-Co nanospheres can be regulated close to ∼100 nm by controlling the molar ratio of Sm:Co precursor. The spherical aggregates exhibited Sm2Co7 phase as a major constituent; while the aggregates obtained at higher Co concentration showed co-existence of Co-phase with Sm2Co7 phase. Upon annealing, the biphasic nature of nanospheres (Sm2Co7/Co) transformed into Sm2Co17 structure. By varying the Sm:Co precursor ratio from 1:5 to 1:9, the coercivity (Hc) and magnetization (Ms) values of the as-synthesized nanospheres can be tuned from 336 to 140 Oe and from 63.7 to 108 emu/g, respectively, and these values significantly improved after annealing. Maximum values of Hc (1050 Oe) at the Sm:Co molar ratio of 1:5 and Ms of 184.6 emu/g at the Sm:Co molar ratio of 1:9 were achieved in the annealed samples. 相似文献
995.
Barium hexaferrite BaFe12O19 powders have been synthesized using the modified co-precipitation method. Modification was performed via the ultrasonication of the precipitated precursors at room temperature for 1 h and the additions of the 2% KNO3, surface active agents and oxalic acid. The results revealed that single phase magnetic barium hexaferrite was formed at a low annealing temperature of 800 °C for 2 h with the Fe3+/Ba2+ molar ratio 8. The microstructure of the powders appeared as a homogeneous hexagonal platelet-like structure using 2% KNO3 as the crystal modifier. A saturation magnetization (60.4 emu/g) was achieved for the BaFe12O19 phase formed at 1000 °C for 2 h with Fe3+/Ba2+ molar ratio 8 using 5 M NaOH solution at pH 10 in the presence of 2% KNO3. Moreover, the saturation magnetization was 52.2 emu/g for the precipitated precursor at Fe3+/Ba2+ molar ratio 12 in was achieved for the precipitated precursor ultrasonicated for 1 h and then annealed at 1200 °C for 2 h. Coercivities from 956.9 to 4558 Oe were obtained at different synthesis conditions. 相似文献
996.
Xiaolian ChaoZupei Yang Mingyuan DongYi Zhang 《Journal of magnetism and magnetic materials》2011,323(15):2012-2016
The phase structure, microstructure, piezoelectric properties, dielectric characteristic and the ME effect of magnetoelectric Pb[Zr0.23Ti0.36+0.02(Mg1/2W1/2)+0.39(Ni1/3Nb2/3)]O3 (PZT)+xNi0.8Co0.1Cu0.1Fe2O4 (NCCF) composite ceramics were prepared by the conventional solid state reaction method. The structural analysis of both the constituent phases and their composites was carried out by X-ray diffraction, energy dispersive spectrometry and scanning electron microscopy. The results showed cubic spinel structure for ferrite phase and tetragonal perovskite structure for ferroelectric phase. The piezoelectric constant, dielectric constant, Curie temperature, remanent polarization and coercive electric field decreased with increase of ferrite content. The coercive field strength, saturation magnetization and remanent magnetization increased with increasing ferrite content. 相似文献
997.
Yan Zhang Ying-Ni DuanJian-Min Zhang Ke-Wei Xu 《Journal of magnetism and magnetic materials》2011,323(6):842-848
Under GGA, size dependence of the geometrical structures, stabilities and magnetic properties of FeCon−1 clusters (n≤16) have been investigated together with the Con clusters for comparison using DFT within the PAW method implemented in VASP. The replaced Fe atom is favorable to occupy the surface position except for FeCo13. The peaks appeared at n=6, 9 and 11 for FeCon−1 clusters and at n=6, 9 and 12 for Con clusters on the size dependence of second difference of total energy imply that these clusters possess relatively higher stability. The magnetic moment is strongly correlated with the effective hybridization, which is closely related to the average bond length 〈d〉 and average coordination number 〈nc〉. A small change in the total charge of Fe atom in FeCon−1 clusters will lead to a relative large reverse change in the total magnetic moment of Fe atom. 相似文献
998.
999.
M. ElMassalami D. da S. OliveiraH. Takeya 《Journal of magnetism and magnetic materials》2011,323(16):2133-2136
Based on extensive Mossbauer effect (ME) and magnetization measurements, the orthorhombic AlFe2B2 was characterized as a ferromagnet (FM) because this character is evident as an onset of a FM transition at Tc=320 K and characteristic magnetizations isotherms below Tc. At liquid helium temperatures, the magnetization saturates to μsat≈1μB per Fe atom; a value which is half the one reported for the iron metal indicating a relatively more filled 3d band. The ME analysis revealed a hyperfine field H(0) of 88(2) kOe, an isomer shift (relative to Fe) of 0.50(2) mm/s, and a quadrupole parameter of 0.02 mm/s: all parameters extrapolated to zero Kelvin. The itinerant character of the magnetic moment will be discussed. 相似文献
1000.
Sudhakar PandayB.S.S. Daniel P. Jeevanandam 《Journal of magnetism and magnetic materials》2011,323(17):2271-2280
Nanocrystalline Co-Ni alloys with different compositions were prepared by polyol reduction of mixed cobalt nickel hydroxides. The precursors (mixed cobalt nickel hydroxides) were prepared by co-precipitation. Powder X-ray diffraction analysis indicated the formation of fcc phase in the alloys and their crystallite size in the range 17-25 nm. Scanning electron microscopy and transmission electron microscopy studies revealed the morphology of the particles as being close to spherical, and the energy dispersive X-ray analysis showed the stoichiometry of the alloys. The magnetization as a function of field and temperature of the alloys, measured using a superconducting quantum interference device, showed superparamagnetic behavior with negligible coercivity and remanence values. 相似文献