Search

Your search keyword '"Cui, X.G."' showing total 47 results
Start Over Author "Cui, X.G." Search Limiters Peer Reviewed
47 results on '"Cui, X.G."'

23. Design and fabrication of sintered Nd-Fe-B magnets with a low temperature coefficient of intrinsic coercivity

Author

Cui X.G., Yan M., Ma T.Y., Luo W., and Tu S.J.

Subjects
sintered Nd-Fe-B magnets, analysis of influencing factors, magnetic properties, low temperature coefficient β, Chemical technology, TP1-1185
Abstract

To decrease the temperature coefficients of sintered Nd-Fe-B magnets, the influencing factors on temperature coefficients, especially the reversible temperature coefficient β of intrinsic coercivity Hcj, were analyzed. The results showed that the absolute value of β decreased with increasing Hcj and also the ratio of microstructure parameter c to Neff, indicating that the increase of magnetocrystalline anisotropy field HA and c/Neff can effectively decrease the absolute value of β. On the basis of this analysis, a sintered Nd-Fe-B magnet with a low temperature coefficient of Hcj was fabricated through composition design, and the value of β was only -0.385%/ºC in the temperature interval of 20-150ºC.

Published
2009
Full Text
View/download PDF

34. Superparamagnetic behavior in Fe ultrathin films on GaN(0001)

Author

Wong, P.K.J., Zhang, W., Cui, X.G., Will, I.G., Xu, Y.B., Tao, Z.K., Li, Xueliang, Li, X., Xie, Z.L., and Zhang, R.

Subjects
METIS-279136, Reflection high-energy electron diffraction, Materials science, Condensed matter physics, EWI-19685, IR-76076, Magnetic hysteresis, law.invention, SQUID, Magnetization, Electron diffraction, law, Magnetic refrigeration, Superparamagnetism, Molecular beam epitaxy
Abstract

In this paper, growth, structural and magnetic properties of ultrathin Fe grown on GaN(OOOl) by molecular beam epitaxy. The films and their surfaces were monitored by in-situ reflection high energy electron diffraction (RHEED) and a crystal thickness monitor. The magnetic properties of the samples were determined by a superconducting quantum interference device (SQUID) magnetometer. Superparamagnetism (SPM) of the ultrathin Fe can be activated at the ambient temperature.the hysteresis loop of an as-deposited 5 ML Fe(llO) film on GaN(0001) taken at RT and reveals that the loop on one hand has an unsaturated magnetization and on the other hand possesses tiny but noticeable Mr and Hc. These two characteristics as a whole imply a coexistence of SPM and weak FM in the ultrathin film. In order to gain further insight into this mixed magnetic state, temperature dependence of the magnetization M(T) in the form of field cooling (FC) and zero field cooling (ZFC) curves of the 5 ML sample was measured by SQUID in a T range between 5 and 300 K.

Published
2010

35. Ultrathin Fe3O4 epitaxial films on wide bandgap GaN(0001)

Author

Wong, P.K.J., Zhang, W., Cui, X.G., Wu, J., Xu, Y.B., Tao, Z.K., Li, X., Xie, Z.L., Zhang, R., and van de Laan, G.

Subjects
IR-75999, EWI-19586, METIS-279135
Abstract

Ultrathin films of magnetite Fe3O4 have been grown epitaxially on wurtzite wide bandgap semiconductor GaN0001 surfaces using molecular-beam epitaxy. Reflection high-energy electron-diffraction patterns show a 111 orientation of the Fe3O4 films and in-plane epitaxial relationship of 11¯0Fe3O4 112¯0GaN and 112¯Fe3O4 11¯00GaN with the GaN0001. X-ray photoelectron spectroscopy and x-ray magnetic circular dichroism confirm the growth of stoichiometric Fe3O4, instead of -Fe2O3. The magnetic hysteresis loops and saturation magnetization Ms obtained by superconducting quantum interference device at room temperature show fast saturation of the Fe3O4 films with the magnetization close to that of the bulk single-crystal value. In-plane magnetoresistance MR measurements reveal negligibly small MR effects, further indicating that the films are free from antiphase boundaries.

Published
2010

46. Ferromagnetic Fe3N films grown on GaN(0002) substrates by MOCVD

Author

Tao, Z.K., Cui, X.G., Zhang, R., Xiu, X.Q., Xie, Z.L., and Zheng, Y.D.

Subjects
*GALLIUM nitride, *SEMICONDUCTOR films, *CRYSTAL growth, *FERROMAGNETISM, *METAL organic chemical vapor deposition, *IRON ions, *TEMPERATURE effect, *SURFACES (Technology)
Abstract

Abstract: We have grown Fe3N films on GaN(0002) substrates by metalorganic chemical vapor deposition (MOCVD). Under lower growth temperatures, small iron particles were formed on GaN surface, while under higher growth temperatures, Fe3N films were formed. The surface morphology of samples with different growth temperatures were characterized by atomic force microscopy. In X-ray Photoelectron Spectroscopy (XPS) measurement, the coexistence of metallic Fe and Fe2+ or Fe3+ was observed in the sample grown at 600°C, while the sample grown at 1050°C showed only high valence forms of Fe ions. It was also found that the magnetic moments of Fe3N prefer to align normal to the c-axis. [Copyright &y& Elsevier]

Published
2010
Full Text
View/download PDF

47. Effect of SiO2 nanopowders on magnetic properties and corrosion resistance of sintered Nd–Fe–B magnets

Author

Cui, X.G., Yan, M., Ma, T.Y., Luo, W., and Tu, S.J.

Subjects
*MAGNETS, *NANOSTRUCTURED materials, *SILICA, *MAGNETIC properties, *CORROSION resistant materials, *SINTER (Metallurgy), *MICROSTRUCTURE, *X-ray spectroscopy
Abstract

Abstract: To improve the magnetic properties and corrosion resistance of magnet, SiO2 nanopowders were added into Nd28.25Dy2.75FebalAl0.15Ga0.1Nb0.1B0.98-sintered magnets as grain boundary modifiers. It was found that the intrinsic coercivity (H cj), remanence (B r) and corrosion resistance were all improved with addition of certain amount of SiO2 nanopowders. The optimum addition amount of SiO2 nanopowders was found to be 0.01wt%. Thermodynamic calculation in combination of energy dispersive X-ray spectroscopy (EDX) analyses indicated that SiO2 nanopowders reacted with Nd of Nd-rich phase. As a result, the intergranular phase was modified, and the grain growth of main phase was restrained. It led to the optimization of microstructure. [Copyright &y& Elsevier]

Published
2009
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results