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3. Permanent magnetic properties of NdFe12Nx sputtered films epitaxially grown on V buffer layer.

Author

Sato, T., Ohsuna, T., Yano, M., Kato, A., and Kaneko, Y.

Subjects
*MAGNETIC properties, *MAGNETISM, *MAGNESIUM oxide, *ALKALINE earth oxides, *MAGNESIUM compounds
Abstract

To clarify the magnetic properties of the NdFe12Nx compound, which shows promise as a highperformance permanent magnet material, NdFe12Nx epitaxial films fabricated by using a V underlayer on MgO (100) single-crystalline substrates were investigated. Nd-Fe films deposited on a V underlayer consist of NdFe12 grains, which have a c-axis orientation perpendicular to the film plane, as well as α-Fe and Nd2Fe17 phases. In the Nd-Fe-N film obtained by subsequent nitridation of the Nd-Fe film, NdFe12Nx grains grew as the dominant phase, and the volume fractions of α-Fe phases dropped below 5%. A Nd-Fe-N film with a thickness of 50 nm exhibits a saturation magnetization (Ms) of 1.7 T, an anisotropy field (HA) of ~60 kOe, a magnetocrystalline anisotropy energy (K1) of ~4.1 MJ/m3, and a coercivity (Hc) of 1.7 kOe. The Hc of a Nd-Fe-N film with a thickness of 25 nm is 4.3 kOe. These results indicate that NdFe12Nx compounds have a superior Ms compared to Nd-Fe-B magnets, while the enhancement in Hc is indispensable. [ABSTRACT FROM AUTHOR]

Published
2017
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6. Porous materials: Looking through the electron microscope

Author

Terasaki, O., primary, Ohsuna, T., additional, Liu, Z., additional, Kaneda, M., additional, Kamiya, S., additional, Carlsson, A., additional, Tsubakiyama, T., additional, Sakamoto, Y., additional, Inagaki, S., additional, Che, S., additional, Tatsumi, T., additional, Camblor, M.A., additional, Ryoo, R., additional, Zhao, D., additional, Stucky, G., additional, Shindo, D., additional, and Hiraga, K., additional

Published
2002
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11. Synthesis, identification, and growth mechanism of Fe, Ni, and Co crystals encapsulated in multiwalled carbon nanocages

Author

Yosida, Y., Shida, S., Ohsuna, T., and Shiraga, N.

Subjects
Crystals -- Growth, Cobalt alloys -- Research, Semiconductors -- Research, Physics
Abstract

A standard dc arc evaporation method facilitates the synthesis of nanometer size crystalline particles of Co3C, beta-Co, alpha-Fe, Ni and gamma-Fe in multiwalled carbon nanocages. X-ray energy dispersive spectroscopic analysis of the crystals yields a spectrum that displays carbon- and metal-associated peaks only. The crystalline size distribution of the encapsulated crystals with gamma-Fe and alpha-Fe smaller than 15nm does not agree with that of crystals with alpha-and gamma-Fe larger than 15nm. The influence of encapsulation on particle growth process accounts for the difference.

Published
1994

12. Structure of the microporous titanosilicate ETS-10

Author

Anderson, M.W., Terasaki, O., Ohsuna, T., Philippou, A., MacKay, S.P., Ferreira, A., Rocha, J., and Lidin, S.

Subjects
Lattice dynamics -- Research, Electron microscopy -- Usage, Molecules -- Research, Titanium compounds -- Analysis, Silicates -- Analysis, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Microporous titanosilicate ETS-10 is composed of SiO4 tetrahedra and TiO6 octahedra interlinked with oxygen atoms. The pore system comprises 12-membered rings with a high degree of disorder. High-resolution electron microscopy, electron and power X-ray diffraction, solid-state NMR, molecular modeling and chemical analysis are used to elucidate the structure of ETS-10.

Published
1994

20. Enhancement of coercivity for Nd-Fe-B thin films by the infiltration of Nd-Cu alloy cap layer.

Author

Sato, T., Oka, N., Ohsuna, T., Kaneko, Y., Suzuki, S., and Shima, T.

Subjects
NEODYMIUM, THIN films, COPPER alloys, ANNEALING of metals, CRYSTAL grain boundaries
Abstract

In order to understand the mechanism of coercivity (Hc) of Nd-Fe-B magnets, we have investigated the effect of thermal annealing treatment on Nd-Fe-B thin films with Nd-Cu alloy cap layers. A substantial enhancement of Hc from 19.0 kOe (1512 kAm-1) to 26.1 kOe (2078 kAm-1) was obtained for the Nd-Fe-B/Nd36Cu64 films after post-annealing at 400 °C. Through electron microscope observation, it was revealed that Nd and Cu enrichment is clearly observed in the grain boundary of the Nd-Fe-B layer, whereas the concentration of Fe was decreased there. These results suggest that the exchange coupling between Nd2Fe14B grains is weakened by the infiltration of a non-magnetic element into the grain boundary after the optimum thermal annealing treatment. [ABSTRACT FROM AUTHOR]

Published
2011
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31. Origin of nondetectable x-ray diffraction peaks in nanocomposite CuTiZr alloys

Author

Jiang, Jianzhong, Kato, H., Ohsuna, T., Saida, J., Inoue, A., Saksl, K., Franz, H., Ståhl, Kenny, Jiang, Jianzhong, Kato, H., Ohsuna, T., Saida, J., Inoue, A., Saksl, K., Franz, H., and Ståhl, Kenny

Abstract

Microscopic structures of Cu60Ti10+xZr30-x (x=0 and 10) alloys have been investigated by transmission electron microscopy, x-ray diffraction (XRD) and differential scanning calorimeter (DSC). In the Cu60Ti10Zr30 samples annealed at 708 K for times ranging from 0 to 130 min, where the enthalpy of the first exothermic peak decreases by 80%, the corresponding XRD patterns still look similar to that for the as-prepared sample. However, the simulated XRD patterns for the pure Cu51Zr14 phase, which is the crystalline phase formed during the first exothermic reaction, with small grain sizes and defects clearly show a broadened amorphous-like feature. This might be the reason that no diffraction peaks from the nanocrystalline component were detected in the XRD patterns recorded for the as-cast or as-spun Cu60Ti10+xZr30-x (x=0 and 10) alloys and for the alloys annealed at lower temperatures, in which the enthalpy of the first exothermic peak has a significant reduction. The second exothermic peak found in DSC curves is due to the formation of another hexagonal phase, spacing group P6(3)/mmc (194) and lattice parameters a=5.105 A and c=8.231 Angstrom.

Published
2003

32. Is Cu60Ti10Zr30 a bulk glass-forming alloy?

Author

Jiang, Jianzhong, Saida, J., Kato, H., Ohsuna, T., Inoue, A., Jiang, Jianzhong, Saida, J., Kato, H., Ohsuna, T., and Inoue, A.

Abstract

The microstructures of Cu60Ti10Zr30 alloys fabricated by using two different methods, (rods of 2.5 mm in diameter prepared by a copper-mold casting method, and ribbons of about 0.03 mm in thickness prepared by the melt-spinning method), have been investigated by transmission electron microscopy and high-resolution transmission electron microscopy. Surprisingly, we found that the alloy in both geometries contains cubic nanometer-sized crystals of about 5-7 nm in diameter with a lattice parameter of 0.45 nm for ribbons and 7-15 nm in diameter with a lattice parameter of 0.42 nm for rods. Nanocrystals with a significant volume fraction are randomly distributed in the amorphous matrix. The copper element is enriched in nanocrystals while a slightly high zirconium content is found in the matrix. We classify that the Cu60Ti10Zr30 alloy prepared by both of the aforementioned methods is a nanocomposite: Nanocrystals embedded in an amorphous matrix.

Published
2003

39. Zeolite syntheses using linear diquats of varying length in fluoride media. The synthesis of ITQ-8, ITQ-10, ITQ-14 and high silica Nu-87Electronic supplementary information (ESI) available: 1H and 13C NMR spectra of MnBQ2+ linear diquats and XRD pattern of the “unknown material” from Table 4. See http://www.rsc.org/suppdata/jm/b1/b105273j/

Author

Díaz-Cabañas, M. J., primary, Camblor, M. A., additional, Liu, Z., additional, Ohsuna, T., additional, and Terasaki, O., additional

Published
2002
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