Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 40

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Addendum: Site occupancy of interstitial deuterium atoms in face-centred cubic iron

Machida, Akihiko*; Saito, Hiroyuki*; Sugimoto, Hidehiko*; Hattori, Takanori; Sano, Asami; Endo, Naruki*; Katayama, Yoshinori*; Iizuka, Riko*; Sato, Toyoto*; Matsuo, Motoaki*; et al.

Nature Communications (Internet), 15, p.8861_1 - 8861_2, 2024/10

 Times Cited Count:0 Percentile:0.00(Multidisciplinary Sciences)

In our previous article (Nature Commun. 5, 5063 (2014)), the site occupancies of D atoms dissolved in an fcc Fe metal lattice were investigated via Rietveld refinement of neutron powder diffraction patterns collected at 988 K and 6.3 GPa. The fcc metal lattice has two interstitial sites available for accommodating D atoms: octahedral and tetrahedral sites. The Rietveld refinement revealed that D atoms occupied mainly the octahedral sites with occupancy of 0.532 and slightly the tetrahedral sites with occupancy of 0.056. Subsequent density-functional-theory (DFT) calculations by Antonov (Phys. Rev. Mater. 2019)) showed that the occupation energy on the tetrahedral site was significantly higher than that on the octahedral site; the tetrahedral site occupation was unlikely to occur even at temperatures as high as 988 K. We reexamined the site occupancies of D-atom by Rietveld refinement including extinction correction. As a result, the octahedral occupancy was increased to 0.60 and the tetrahedral occupancy was reduced to zero. The occupation of only the octahedral site for D atom is consistent with the DFT calculation, although in contrast to the previous results.

Journal Articles

Hydrogenation of $$L$$1$$_{2}$$-type AlNi$$_{3}$$ alloy at high pressure and temperature

Endo, Naruki*; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori

Journal of Alloys and Compounds, 645(Suppl.1), p.S61 - S63, 2015/10

 Times Cited Count:0 Percentile:0.00(Chemistry, Physical)

Journal Articles

Hydrogenation of a TiFe-based alloy at high pressures and temperatures

Endo, Naruki*; Saita, Itoko*; Nakamura, Yumiko*; Saito, Hiroyuki; Machida, Akihiko

International Journal of Hydrogen Energy, 40(8), p.3283 - 3287, 2015/03

 Times Cited Count:16 Percentile:37.73(Chemistry, Physical)

Journal Articles

Site occupancy of interstitial deuterium atoms in face-centred cubic iron

Machida, Akihiko; Saito, Hiroyuki; Sugimoto, Hidehiko*; Hattori, Takanori; Sano, Asami; Endo, Naruki*; Katayama, Yoshinori; Iizuka, Riko*; Sato, Toyoto*; Matsuo, Motoaki*; et al.

Nature Communications (Internet), 5, p.5063_1 - 5063_6, 2014/09

 Times Cited Count:64 Percentile:86.93(Multidisciplinary Sciences)

Iron hydride FeH$$_x$$, is thermodynamically stable only at high hydrogen pressure of several GPa. To investigate the hydrogenation process and hydrogen state in iron hydride, it is necessary to carry out the in-situ measurement under high pressure and high temperature. In this study, we performed the in-situ neutron diffraction measurement of Fe-D system using the high pressure neutron diffractometer PLANET in the MLF, J-PARC, and determined the deuterium occupying sites and occupancies in fcc-FeD$$_x$$. We found the minor occupation of tetrahedral sites under high pressure and high temperature. We considered the mechanism of the minor occupation based on the Quantum-mechanical calculation.

Journal Articles

Li$$_{4}$$FeH$$_{6}$$; Iron-containing complex hydride with high gravimetric hydrogen density

Saito, Hiroyuki; Takagi, Shigeyuki*; Matsuo, Motoaki*; Iijima, Yuki*; Endo, Naruki*; Aoki, Katsutoshi*; Orimo, Shinichi*

APL Materials (Internet), 2(7), p.076103_1 - 076103_7, 2014/07

 Times Cited Count:25 Percentile:68.75(Nanoscience & Nanotechnology)

Journal Articles

Researches on Ti-alloy hydrides under high pressure and high temperature with the aid of in-situ synchrotron radiation X-ray diffraction measurements

Endo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori

Materia, 53(3), p.94 - 99, 2014/03

no abstracts in English

Journal Articles

Synthesis and formation process of Al$$_{2}$$CuH$$_{x}$$; A New class of interstitial aluminum-based alloy hydride

Saito, Hiroyuki; Takagi, Shigeyuki*; Endo, Naruki; Machida, Akihiko; Aoki, Katsutoshi; Orimo, Shinichi*; Katayama, Yoshinori

APL Materials (Internet), 1(3), p.032113_1 - 032113_7, 2013/09

 Times Cited Count:15 Percentile:52.59(Nanoscience & Nanotechnology)

Journal Articles

Formation of BCC TiFe hydride under high hydrogen pressure

Endo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori

International Journal of Hydrogen Energy, 38(16), p.6726 - 6729, 2013/05

 Times Cited Count:25 Percentile:53.40(Chemistry, Physical)

Journal Articles

Magnetic properties of single crystalline YbFe$$_{2}$$O$$_{4}$$

Yoshii, Kenji; Mizumaki, Masaichiro*; Matsumoto, Keisuke*; Mori, Shigeo*; Endo, Naruki; Saito, Hiroyuki; Matsumura, Daiju; Kambe, Takashi*; Ikeda, Naoshi*

Journal of Physics; Conference Series, 428, p.012032_1 - 012032_5, 2013/04

 Times Cited Count:15 Percentile:97.01(Chemistry, Applied)

We have investigated a single crystal of multiferroic YbFe$$_{2}$$O$$_{4}$$. Its magnetic transition temperature was 250 K. The magnetization along the c-axis was much larger than that within the ab plane, indicating the Ising character of this system. The field-cooled magnetization became negative below 10 K. This was explained in terms of an antiparallel coupling between Yb and Fe moments. Magnetocaloric effects were also observed. The change of entropy was found to show a broad peak with a width of 100 K, which is favorable to application.

Journal Articles

Formation process of perovskite-type hydride LiNiH$$_{3}$$; ${it In situ}$ synchrotron radiation X-ray diffraction study

Sato, Ryutaro*; Saito, Hiroyuki; Endo, Naruki; Takagi, Shigeyuki*; Matsuo, Motoaki*; Aoki, Katsutoshi; Orimo, Shinichi*

Applied Physics Letters, 102(9), p.091901_1 - 091901_4, 2013/03

 Times Cited Count:36 Percentile:78.05(Physics, Applied)

Journal Articles

Density-functional study of perovskite-type hydride LiNiH$$_{3}$$ and its synthesis; Mechanism for formation of metallic perovskite

Takagi, Shigeyuki*; Saito, Hiroyuki; Endo, Naruki; Sato, Ryutaro*; Ikeshoji, Tamio*; Matsuo, Motoaki*; Miwa, Kazutoshi*; Aoki, Katsutoshi; Orimo, Shinichi*

Physical Review B, 87(12), p.125134_1 - 125134_6, 2013/03

 Times Cited Count:21 Percentile:63.69(Materials Science, Multidisciplinary)

Journal Articles

Phase diagram and equation of state of TiH$$_{2}$$ at high pressures and high temperatures

Endo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi

Journal of Alloys and Compounds, 546, p.270 - 274, 2013/01

 Times Cited Count:6 Percentile:34.37(Chemistry, Physical)

Oral presentation

Hydrogenation of Al$$_{2}$$Cu alloy under high pressure and temperature

Saito, Hiroyuki; Endo, Naruki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi

no journal, , 

no abstracts in English

Oral presentation

Rare earth substitution effects in multiferroic RFe$$_{2}$$O$$_{4}$$ (R: rare earths)

Yoshii, Kenji; Matsumura, Daiju; Endo, Naruki; Saito, Hiroyuki; Yoneda, Yasuhiro; Nishihata, Yasuo; Funae, Takeshi*; Ejiri, Hiroki*; Kano, Jun*; Kobayashi, Tatsuo*; et al.

no journal, , 

We have investigated the substitution effects at the rare-earth (R) site in multiferroic RFe$$_{2}$$O$$_{4}$$ (R: Y, Ho-Lu) to explore a new phase of this system. From EXAFS measurements for the R atoms, the large R$$^{3+}$$ ions (such as Dy$$^{3+}$$) was partially substituted in RFe$$_{2}$$O$$_{4}$$. Powder X-ray diffraction showed that this material had a single-phase RFe$$_{2}$$O$$_{4}$$-type structure (space group R-3m). The simulated EXAFS spectrum reproduced the characteristics of the experimental spectrum, confirming that R$$^{3+}$$ is actually settled at the rare earth site. The other results, such as the magnetic properties, will be reported at the conference.

Oral presentation

Formation of a novel TiFe hydride and estimation of its hydrogen content at high pressures and temperatures

Endo, Naruki; Matsumoto, Itoko*; Nakamura, Yumiko*; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori

no journal, , 

Oral presentation

Phase relationship and equation of state of TiH$$_{2}$$ at high pressures and high temperatures

Endo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi

no journal, , 

The phase diagram and the equation of state of TiH$$_{2}$$ at high pressure and high temperature (HPHT) were carefully investigated in the present study using by using an ${it in-situ}$ synchrotron X-ray diffraction measurement for new titanium alloys hydrides development. Summary of the study is as follows: At ambient conditions, the TiH$$_{2}$$ had a face-centered cubic crystal structure (FCC). At high pressure, TiH$$_{2}$$ crystallized in a FCC structure above 200$$^{circ}$$C. In lower temperature range, the TiH$$_{2}$$ structure was not only a FCC structure but also a tetragonal structure. Since the transformation temperature of TiH$$_{2}$$ was increased with increasing pressures, the thermal stability of this phase was increased by pressures. In this presentation, we will report detailed results together with the phase diagram and the equation of TiH$$_{2}$$ state at HPHT.

Oral presentation

Crystal structure of interstitial hydride Al$$_{2}$$CuH$$_{x}$$ (x$$sim$$1)

Saito, Hiroyuki; Takagi, Shigeyuki*; Endo, Naruki; Machida, Akihiko; Aoki, Katsutoshi; Orimo, Shinichi*; Katayama, Yoshinori

no journal, , 

no abstracts in English

Oral presentation

Hydrogenation of CsCl-type Ti${it TM}$ (${it TM}$ = Fe, Co, Ni) alloys at high pressure and temperature

Endo, Naruki; Ishikawa, Kazuhiro*; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori

no journal, , 

no abstracts in English

Oral presentation

Structural studies of iron deuteride by in-situ neutron diffraction measurements under high temperature and high pressure

Machida, Akihiko; Saito, Hiroyuki; Hattori, Takanori; Sano, Asami; Endo, Naruki; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Sato, Toyoto*; Matsuo, Motoaki*; et al.

no journal, , 

no abstracts in English

Oral presentation

In situ neutron diffraction measurement on deuterization process of iron at high pressure and high temperature

Machida, Akihiko; Saito, Hiroyuki; Hattori, Takanori; Sano, Asami; Endo, Naruki*; Watanuki, Tetsu; Katayama, Yoshinori; Iizuka, Riko*; Sato, Toyoto*; Matsuo, Motoaki*; et al.

no journal, , 

Iron hydride FeH$$_x$$, is thermodynamically stable only at high hydrogen pressure of several GPa. Three hydride phases, bcc-FeH$$_x$$ ($$x < 0.05$$), dhcp-FeH$$_x$$ ($$x sim 1$$), and fcc-FeH$$_x$$ ($$x = 0 - 1$$) were confirmed at 300-2000 K and 0-20 GPa. In situ neutron diffraction measurement on their deutrides have not been reported yet. A high pressure neutron diffractometor, PLANET, constructed at Materials and Life Science Experimental Facility at J-PARC, enables us to perform in situ neutoron diffraction measurements on deuterization process of metals at high pressure and high temperature. With PLANET, the deuteration process of iron was investigated at a pressure of about 7 GPa and temperatures up to about 1000 K. This in situ measurement was successfully made using a deuterization reaction cell developed for neutron diffraction measurement. We observed the bcc-fcc transition of pure iron around 800 K and successive deuterization of fcc-Fe around 870 K.

40 (Records 1-20 displayed on this page)