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Journal Articles

Doping effect on charge ordered structure in RFe$$_{2}$$O$$_{4}$$(R=Lu and Yb)

Matsuo, Yoji*; Mori, Shigeo*; Hirata, Akihiko*; Yoshii, Kenji; Ikeda, Naoshi*

Journal of Physics; Conference Series, 200, p.012128_1 - 012128_4, 2010/02

 Times Cited Count:3 Percentile:77.33

RFe$$_{2}$$O$$_{4}$$ (R= Ho-Lu,Y) is a novel ferroelectric material in which ferroelectric polarization is caused by the charge ordering (CO) of Fe$$^{2+}$$ and Fe$$^{3+}$$. In this work we investigated the CO structure and dielectric/magnetic properties in RFe$$_{2}$$O$$_{4}$$ and RFeCuO$$_{4}$$ (R=Lu,Yb, M=Cu,Co) by a transmission electron microscopy (TEM), combining with dielectric and magnetic measurements. LuFeCuO$$_{4}$$ is a dielectric compound, which shows the characteristic low-frequency dielectric dispersion. In addition, the Cu$$^{2+}$$ substitution in LuFe$$_{2}$$O$$_{4}$$ suppressed the formation of the CO structure and induced characteristic polar nanodomains with the 5-10nm size. Magnetic measurement revealed that LuFeCuO$$_{4}$$ shows the magnetic transition around 50K, which is much lower than the magnetictransition temperature of 250K in LuFe$$_{2}$$O$$_{4}$$. Our experimental results suggest that the polar nanodomains should be responsible for the magnetic/dielectric properties in RFeMO$$_{4}$$.

Journal Articles

Nanometer-sized domain structures in LuFe$$M$$O$$_{4}$$ ($$M$$=Cu, Co) revealed by energy-filtered transmission electron microscopy

Matsuo, Yoji*; Hirata, Akihiko*; Horibe, Yoichi*; Yoshii, Kenji; Ikeda, Naoshi*; Mori, Shigeo*

Ferroelectrics, 380(1), p.56 - 62, 2009/06

 Times Cited Count:6 Percentile:31.42(Materials Science, Multidisciplinary)

Diluted effect on the charge ordered (CO) structure in dielectric materials LuFe$$M$$O$$_{4}$$ ($$M$$=Cu, Co) were investigated by an energy-filtered transmission electron microscope (TEM), in combination with a conventional TEM. It is revealed that partial substitution of Cu$$^{2+}$$ and Co$$^{2+}$$ for Fe$$^{2+}$$ in LuFe$$_{2}$$O$$_{4}$$ destabilized the CO structure. In LuFeCuO$$_{4}$$, there exist characteristic zigzag-shaped diffuse streaks and diffuse spots at the h/3-$$delta$$ h/3-$$delta$$ 0-type positions (h: integer, $$delta$$=0.06) in reciprocal space, which originate from static cationic ordering of Fe$$^{3+}$$ and Cu$$^{2+}$$ ions in the triangular lattice. Moreover, real-space images by the energy-filtered TEM revealed that nanometer-sized domain structures with the 5$$sim$$10 nm size are formed. In contrast, honeycomb-shaped diffuse streaks were found in LuFeCoO$$_{4}$$, in which no domain structures are observed in real-space images.

Journal Articles

Chemical studies on rutherfordium (Rf) at JAERI

Nagame, Yuichiro; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Ishii, Yasuo; Sato, Tetsuya; Hirata, Masaru; Nishinaka, Ichiro; Ichikawa, Shinichi; et al.

Radiochimica Acta, 93(9-10), p.519 - 526, 2005/00

 Times Cited Count:29 Percentile:88.24(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Fluoride complexation of element 104, rutherfordium

Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Nishinaka, Ichiro; Hirata, Masaru; Yaita, Tsuyoshi; Ichikawa, Shinichi; Nagame, Yuichiro; et al.

Journal of the American Chemical Society, 126(16), p.5219 - 5224, 2004/04

 Times Cited Count:42 Percentile:73.39(Chemistry, Multidisciplinary)

Fluoride complexation of element 104, rutherfordium (Rf), produced in the $$^{248}$$Cm($$^{18}$$O,5n)$$^{261}$$Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchangechromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the $$^{18}$$O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effect on the fluoride complexation of Rf.

Journal Articles

Anion-exchange behavior of Rf in HCl and HNO$$_{3}$$ solutions

Haba, Hiromitsu; Tsukada, Kazuaki; Asai, Masato; Goto, Shinichi*; Toyoshima, Atsushi; Nishinaka, Ichiro; Akiyama, Kazuhiko; Hirata, Masaru; Ichikawa, Shinichi; Nagame, Yuichiro; et al.

Journal of Nuclear and Radiochemical Sciences, 3(1), p.143 - 146, 2002/06

We have investigated the sorption behavior of element 104 rutherfordium (Rf) on an anion exchange resin from HCl and HNO$$_{3}$$ solutions. In the HCl experiments, the distribution coefficients of Rf increase with an increase of HCl concentration from 7.0 M to 11.5 M, indicating that anionic species such as [Rf(OH)Cl$$_{5}$$]$$^{2-}$$ or [RfCl$$_{6}$$]$$^{2-}$$ are formed. This sorption behavior of Rf is typical of the group-4 elements Zr and Hf, and is quite different from that of the pseudo-homologue Th. It is also noted that the distribution coefficients decrease in the order Rf, Zr, Hf at 9.0 M HCl, which is consistent with the expected order of ionic radii. On the other hand, Rf appears to behave like Zr and Hf in 8 M HNO$$_{3}$$ not like Pu and Th.

Journal Articles

Startup of transactinide chemistry in JAERI

Haba, Hiromitsu; Tsukada, Kazuaki; Asai, Masato; Nishinaka, Ichiro; Sakama, Minoru*; Goto, Shinichi*; Hirata, Masaru; Ichikawa, Shinichi; Nagame, Yuichiro; Kaneko, Tetsuya*; et al.

Radiochimica Acta, 89(11-12), p.733 - 736, 2002/02

 Times Cited Count:14 Percentile:70.96(Chemistry, Inorganic & Nuclear)

no abstracts in English

Oral presentation

Formation of anionic chloride complex of Rutherfordium (Rf)

Tsukada, Kazuaki; Toyoshima, Atsushi; Haba, Hiromitsu*; Asai, Masato; Akiyama, Kazuhiko*; Ishii, Yasuo; Tome, Hayato*; Nishinaka, Ichiro; Sato, Tetsuya; Ichikawa, Takatoshi; et al.

no journal, , 

no abstracts in English

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