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論文

$^{149}$ Sm synchrotron-radiation-based Mssbauer and SR studies of SmRuGe $_{13}$

筒井智嗣; 伊藤孝; 中村仁*; 吉田実生*; 小林義男*; 依田芳卓*; 中村惇平*; 幸田章宏*; 東中隆二*; 青木大*; et al.

Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12

https://doi.org/10.1007/s10751-024-01900-6

$^{149}$ Sm SR-based Mssbauer and muon spin relaxation (SR) spectroscopies have been applied to SmRuGe $_{13}$ . The temperature dependence of the $^{149}$ Sm SR-based Mssbauer spectra in the paramagnetic state implies the presence of dynamical nuclear Zeeman and/or quadrupole interactions. The time differential SR spectra also exhibit a marked temperature dependence in the paramagnetic state, indicating the presence of magnetic fluctuation in SmRuGe $_{13}$ at least. These results in the present work infer that the dynamical hyperfine interactions observed using the mutually complementary spectroscopic methods are connected with the mechanism of the heavy fermion behavior in SmRuGe $_{13}$ .

論文

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy of Sm-based heavy fermion compounds

筒井智嗣; 東中隆二*; 水牧仁一朗*; 小林義男*; 中村仁*; 伊藤孝; 依田芳卓*; 松田達磨*; 青木勇二*; 佐藤英行*

Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12

https://doi.org/10.1007/s10751-024-01851-y

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy has been applied to Sm-based heavy fermion intermetallics, SmAl $_{20}$ ( = Ti, V and Cr) and SmOs $_{4}$ Sb $_{12}$ . The isomer shifts obtained demonstrate that the Sm valence states in these compounds are intermediate. Since the difference of the isomer shifts in 22.502 keV $^{149}$ Sm Mssbauer effect between Sm $^{2+}$ and Sm $^{3+}$ state is comparable to the 2nd order Doppler shift, consideration of the 2nd order Doppler shift is required to precisely discuss Sm valence state through the shifts of the Mssbauer spectra. In addition, the plots of the isomer shifts obtained by the Mssbauer spectroscopy against the Sm valence states estimated from Sm L-edge X-ray absorption spectroscopy exhibit a linear correlation except for that in SmOsSb $_{12}$ . This implies that the origin of the intermediate valence state in SmOsSb $_{12}$ differs from that in SmAl $_{20}$ ( = Ti, V and Cr).

論文

Ca-induced phonon softening in BaTiO $_{3}$ revealed by inelastic X-ray and neutron scattering

木村耕治*; 筒井智嗣*; 山本裕太*; 中埜彰俊*; 川村啓介*; 梶本亮一; 蒲沢和也*; Martin, A.*; Webber, K. G.*; 柿本健一*; et al.

Physical Review B, 110(13), p.134314_1 - 134314_10, 2024/10

https://doi.org/10.1103/PhysRevB.110.134314

被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

We performed inelastic X-ray and neutron scattering (IXS and INS) experiments for (Ba,Ca)TiO $_{3}$ single crystals to elucidate the effect of Ca doing on the atomic dynamics. Dispersion relations of transverse phonons in BaTiO $_{3}$ , (Ba $_{0.9}$ Ca $_{0.1}$ )TiO $_{3}$ , and (Ba $_{0.8}$ Ca $_{0.2}$ )TiO $_{3}$ were determined. The -site-O vibrational mode as well as the acoustic mode were observed both by IXS and INS, whereas the Ti-O soft mode was detected only by INS. It was found that the -site-O vibration exhibits significant softening with increasing Ca concentration, while the Ti-O soft mode is almost unaffected by the Ca doping. This finding is discussed in comparison with the polarization hysteresis loops and piezoelectric coefficients of (Ba,Ca)TiO $_{3}$ . It is indicated that the softening of the -site-O vibration contributes to the enhancement of the piezoelectricity of Ca-doped BaTiO $_{3}$ -based materials.

論文

Lattice dynamics of CH(NH $_{2}$ ) $_{2}$ PbI $_{3}$ and CH(NH $_{2}$ ) $_{2}$ SnI $_{3}$ investigated by inelastic X-ray scattering and comparison of their elastic properties

玉造博夢; 村上洋一*; 齋藤紀子*; 大橋直樹*; 筒井智嗣*

Physical Review B, 110(2), p.024301_1 - 024301_8, 2024/07

https://doi.org/10.1103/PhysRevB.110.024301

被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

Using the inelastic X-ray scattering (IXS) technique, we investigate the lattice dynamics of inorganic-organic hybrid iodide perovskites FAPbI $_{3}$ and FASnI $_{3}$ (FA CH(NH $_{2}$ ) $_{2}$ , formamidinium) in their cubic phase and tetragonal phase. We find that the IXS spectra of FASnI $_{3}$ are highly broad at all momentum points, as has been widely observed in the Pb-based halide perovskites. The speeds of sound (phonon group velocities) and absolute values of elastic constants of FASnI $_{3}$ are smaller than those of FAPbI $_{3}$ in both phases. In addition, no significant difference in the phonon lifetimes of FAPbI $_{3}$ and FASnI $_{3}$ is observed. These results correlate better with the reported tendency that the lattice thermal conductivity of ASnX $_{3}$ is lower than that of APbX $_{3}$ . We discuss that our results also favor the up-conversion mechanism by acoustic phonons in the phonon bottleneck effect for the long lifetime of hot carriers.

論文

Effect of inner wall cracking on the cavitation bubble formation in the mercury spallation target at J-PARC

有吉玄; 猿田晃一; 粉川広行; 二川正敏; 前野航希*; Li, Y.*; 筒井喜平*

Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.1407 - 1420, 2023/08

https://doi.10.13182/NURETH20-41514

水銀を核破砕標的とするパルス中性子源では、陽子線励起圧力波による標的容器のキャビテーション損傷が問題視されている。このような損傷の抑制手法として、旋回流式気泡注入器で水銀中に微小He気泡を混合し、その圧縮性効果を用いる手法や、標的容器内側に流路壁を追加した二重壁流路構造を設ける手法が採用されている。本研究では、二重壁流路体系において内壁部に生じ得るキャビテーション由来の貫通損傷を標的容器外部から検出する異常診断技術の確立を目指す。本論文では、貫通損傷が生じた場合の水銀流れを有限要素法に基づく流動解析で明らかにし、流体励起・音響振動の観点から、損傷の影響を評価した結果を報告する。

論文

Investigation of the phonon dispersion associated with superlattice reflections in the BiS $_{2}$ -based superconductor LaBiS $_{2}$ O $_{0.5}$ F $_{0.5}$

玉造博夢; 長谷川巧*; 佐賀山基*; 水牧仁一朗*; 村上洋一*; 梶谷丈*; 東中隆二*; 松田達磨*; 青木勇二*; 筒井智嗣*

Physical Review B, 107(2), p.024303_1 - 024303_8, 2023/01

https://doi.org/10.1103/PhysRevB.107.024303

被引用回数：1 パーセンタイル：14.50(Materials Science, Multidisciplinary)

The phonon dispersion of a BiS $_{2}$ -based superconductor LaBiS $_{2}$ O $_{0.5}$ F $_{0.5}$ is investigated by first-principles calculations and inelastic X-ray scattering experiments. The origin of superlattice (SL) reflections arising from transverse-type lattice modulation, which were recently reported in [J. Kajitani ., J. Phys. Soc. Jpn. , 103601 (2021)], is discussed in terms of lattice dynamics. Our first-principles calculations of phonon dispersion and the Fermi surfaces (FSs) demonstrate that the phonon mode corresponding to the transverse-type lattice modulation is unstable, and the propagation vector corresponding to the SL reflections is close to the FS nesting vector, which suggests that the phonon softening originates from the FS nesting. Against these calculated expectations, measured phonon dispersion in LaBiS $_{2}$ O $_{0.5}$ F $_{0.5}$ along the Z-A direction, where the SL point is located, shows no remarkable temperature dependence, and there are no steeply declining branches accompanied with a softening around the SL point. Based on these results, we discuss the two possibilities for the transverse lattice modulation in LaBiS $_{2}$ O $_{0.5}$ F $_{0.5}$ : the order-disorder type structural transition and the displacive structural transition with an overdamped mode, for both of which the local structure distortion or the short range correlation within the BiS $_{2}$ plane would be essential.

論文

Phonon softening in Lu(Pt $_{1-x}$ Pd)In close to a zero-temperature structural instability

Gruner, T.*; Lucas, S.*; Geibel, C.*; 金子耕士; 筒井智嗣*; Schmalzl, K.*; Stockert, O.*

Physical Review B, 106(11), p.115142_1 - 115142_6, 2022/09

https://doi.org/10.1103/PhysRevB.106.115142

被引用回数：1 パーセンタイル：7.68(Materials Science, Multidisciplinary)

The disappearance of a charge-density-wave (CDW) transition in Lu(Pt $_{1-x}$ Pd)In is thought to be closely linked to a maximum of the superconducting transition temperature in the system. We studied the superstructure and the phonon softening in Lu(Pt $_{0.5}$ Pd $_{0.5}$ )In by means of neutron and high-resolution inelastic X-ray scattering. A full phonon softening at $q_{textrm{CDW}}$ = (0.5, 0.5, 0) with the appearance of superstructure peaks could be clearly identified. The large tail of the superstructure intensity above the CDW transition indicates the importance of critical fluctuations.

論文

Sm valence determination of Sm-based intermetallics using $^{149}$ Sm Mssbauer and Sm L $_{rm III}$ -edge X-ray absorption spectroscopies

筒井智嗣; 東中隆二*; 中村頼人*; 藤原孝将*; 中村仁*; 小林義男*; 伊藤孝; 依田芳卓*; 加藤和男*; 新田清文*; et al.

Hyperfine Interactions, 242(1), p.32_1 - 32_10, 2021/12

https://doi.org/10.1007/s10751-021-01759-x

被引用回数：1 パーセンタイル：75.41(Physics, Atomic, Molecular & Chemical)

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy was performed in Sm-based intermetallics having a cubic crystal structure, Sm $_{3}Tr_{4}$ Ge $_{13}$ , SmB $_{6}$ , SmBe $_{13}$ , and Sm $Tr_{2}$ Al $_{20}$ ( = transition metals). In spite of the difference of the local structure around the Sm sites, the observed Mssbauer spectra consist of a single line at 300 K. On the other hand, Sm L $_{rm III}$ -edge X-ray absorption spectra consist of two components, suggesting Sm $^{2+}$ and Sm $^{3+}$ states. Difference of the number of the spectral components between the Mssbauer spectroscopy and X-ray absorption spectroscopy is caused by the difference of the time window in the scattering process of these measurements. Correlation between the isomer shifts in the Mssbauer spectroscopy and average Sm valence states estimated from the X-ray absorption spectroscopy exhibits a linear correlation.

論文

Lattice dynamics in CePdAl and LaPdAl

Doleal, P.*; Cejpek, P.*; 筒井智嗣*; 金子耕士; Legut, D.*; Carva, K.*; Javorsk, P.*

Scientific Reports (Internet), 11(1), p.20878_1 - 20878_10, 2021/10

https://doi.org/10.1038/s41598-021-99904-7

被引用回数：1 パーセンタイル：4.93(Multidisciplinary Sciences)

The interaction between phonons and 4f electrons, which is forming a new quantum state (quasi-bound state) beyond Born-Oppenheimer approximation, is very prominent and lattice dynamics plays here a key role. There is only a small number of compounds in which the experimental observation suggest such a scenario. One of these compounds is CePdAl. The inelastic X-ray scattering technique was used for mapping the phonon modes at X and Z points as well as in L and D directions, where the symmetry analysis of phonon modes was performed. The measured spectra are compared with the theoretical calculation, showing very good agreement. The results are discussed with respect to the magneto-elastic interaction. The phonon mode symmetry A1g was found to be unaffected by the interaction, which is in contrast to previous assumptions.

論文

Nature of structural instabilities in superconducting SrIrSn $_{13}$

金子耕士; Cheung, Y. W.*; Hu, Y.*; 今井正樹*; 谷奥泰明*; 金川響*; 村川譲一*; 森山広大*; Zhang, W.*; Lai, K. T.*; et al.

JPS Conference Proceedings (Internet), 30, p.011032_1 - 011032_6, 2020/03

https://doi.org/10.7566/JPSCP.30.011032

A quantum critical point appears as a second-order phase transition which takes place at zero temperature. In contrast to heavy-fermion systems in which magnetism often plays a vital role, recent studies revealed that structural instabilities can drive a system to a quantum critical point as well. In quasi-skutterudite (Ca,Sr)Sn $_{13}$ (=Rh, Ir), SrIrSn $_{13}$ exhibits superconductivity around $T_{rm sc}$ 5 K and a structural transition at $T^*{simeq}$ 147 K. Applying physical or chemical pressure on SrIrSn $_{13}$ suppresses rapidly, and a quasi-linear dependence of electrical resistivity, signature of non-Fermi liquid behavior, was observed where extrapolates to 0 K. The isomorphs (CaSr $_{1-x}$ )RhSn $_{13}$ exhibits similar behavior, where the criticality can be reached by 0.9 without external pressure. Neutron scattering experiments in SrIrSn $_{13}$ evidences the second order nature of the structural transition at by the observation of a continuous evolution of superlattice peak below and a gradual increase of critical scattering upon approaching to by cooling. Increase of in (CaSr $_{1-x}$ )RhSn $_{13}$ toward the quantum critical point leads to the systematic variation of the critical exponents of the order parameter. In addition, this substitution induces the phonon softening around the M point towards zero energy revealed by inelastic X-ray scattering experiment. We will present systematic variations in both elastic and inelastic channels upon approaching to the quantum critical point.

論文

Evidence of a structural quantum critical point in (CaSr $_{1-x}$ )RhSn $_{13}$ from a lattice dynamics study

Cheung, Y. W.*; Hu, Y. J.*; 今井正樹*; 谷奥泰明*; 金川響*; 村川譲一*; 森山広大*; Zhang, W.*; Lai, K. T.*; 吉村一良*; et al.

Physical Review B, 98(16), p.161103_1 - 161103_5, 2018/10

https://doi.org/10.1103/PhysRevB.98.161103

被引用回数：20 パーセンタイル：63.98(Materials Science, Multidisciplinary)

Approaching a quantum critical point has been an effective route to stabilize superconductivity. While the role of magnetic QCPs has been extensively discussed, similar exploration of a structural QCP is scarce. Using inelastic X-ray scattering, we examine the phonon spectrum of the nonmagnetic quasi-skutterudite (CaSr $_{1-x}$ )RhSn $_{13}$ , which represents a precious system to explore the interplay between structural instabilities and superconductivity by tuning the Ca concentration x. We unambiguously detect the softening of phonon modes around the M point on cooling towards the structural transition. Intriguingly, at x = 0:85, the soft mode energy squared at the M point extrapolates to zero at -5.7 K, providing the first compelling microscopic evidence of a structural QCP in (CaSr $_{1-x}$ )RhSn $_{13}$ . The enhanced phonon density-of-states at low energy provides the essential ingredient for realizing strong-coupling superconductivity near the structural QCP.

論文

Effect of -site randomness on the antiferroelectric/relaxor nature of the ground state; Diffuse and inelastic X-ray scattering study of Pb(In $_{1/2}$ Nb $_{1/2}$ )O

大和田謙二*; 塚田慎也*; 福田竜生; 筒井智嗣*; Baron, A. Q. R.*; 水木純一郎*; 大和英弘*; 安田直彦*; 寺内暉*

Physical Review B, 98(5), p.054106_1 - 054106_10, 2018/08

https://doi.org/10.1103/PhysRevB.98.054106

被引用回数：4 パーセンタイル：18.17(Materials Science, Multidisciplinary)

The effect of -site randomness on the antiferroelectric/relaxor nature of the ground state was investigated by studying diffuse and inelastic X-ray scattering from ordered and disordered Pb(In $_{1/2}$ Nb $_{1/2}$ )O (O- and D-PIN) single crystals. The diffuse scattering measurement of O-PIN (antiferroelectric at ) shows the existence of ferroelectrically interactive local polarization above . Inelastic X-ray scattering shows that the transverse-acoustic (TA) and transverse-optic (TO) modes are dominant at 800 K, while the central peak (CP) and TA modes are coupled and majorly contribute to the critical behavior of the diffuse scattering at . Upon these results, the -site randomness is discussed in terms of suppressing the antiferroelectric instability and enhancing the polarization fluctuation.

論文

Inelastic X-ray scattering of Al ( = La, Ce, = Cu, Au)

筒井智嗣*; 金子耕士; Pospisil, J.; 芳賀芳範

Physica B; Condensed Matter, 536, p.24 - 27, 2018/05

https://doi.org/10.1016/j.physb.2017.09.087

被引用回数：3 パーセンタイル：13.64(Physics, Condensed Matter)

Inelastic X-ray scattering (IXS) experiments of RTAl ( = La Ce, = Cu, Au) were carried out at 300 and 5.5 K. The spectra between LaCuAl and CeCuAl (LaAuAl and CeAuAl) are nearly identical at both temperatures except for temperature factors such as temperature dependence of Bose factor in IXS spectra and effect on thermal expansion. This means that no evident temperature dependence of IXS spectra was observed in CeTAl ( = Cu, Au).

論文

Second-order structural transition in (Ca $_{0.5}$ Sr $_{0.5}$ )RhSn $_{13}$

Cheung, Y. W.*; Hu, Y. J.*; Goh, S. K.*; 金子耕士; 筒井智嗣; Logg, P. W.*; Grosche, F. M.*; 金川響*; 谷奥泰明*; 今井正樹*; et al.

Journal of Physics; Conference Series, 807(3), p.032002_1 - 032002_4, 2017/04

BB2016-0329.pdf:0.86MB

https://doi.org/10.1088/1742-6596/807/3/032002

被引用回数：5 パーセンタイル：81.14(Physics, Condensed Matter)

(Ca $_{0.5}$ Sr $_{0.5}$ )RhSn $_{13}$ is a member of the substitution series (Ca $_{x}$ Sr $_{1-x}$ )RhSn $_{13}$ which has recently been argued to feature a structural quantum critical point at = 0.9. In the stoichiometric compound Sr $_{3}$ Rh $_{4}$ Sn $_{13}$ , the structural transition at 138 K has been shown to be a second-order phase transition. Moving towards xc, we examine the character of the structural transition in (Ca $_{0.5}$ Sr $_{0.5}$ )RhSn $_{13}$ (i.e. = 0.5, 55 K) using electrical resistivity, heat capacity and X-ray scattering. The absence of the thermal hysteresis in specific heat around , and the continuous evolution of the superlattice reflection detected by X-ray diffraction are consistent with the scenario that the structural transition associated with a modulation vector = (0.5, 0.5, 0) in (Ca $_{0.5}$ Sr $_{0.5}$ )RhSn $_{13}$ remains second-order on approaching the quantum critical point.

論文

Impurity effects in the microscopic elastic properties of polycrystalline Mg-Zn-Y alloys with a synchronised long-period stacking ordered phase

細川伸也*; 木村耕治*; 山崎倫昭*; 河村能人*; 吉田亨次*; 乾雅祝*; 筒井智嗣*; Baron, A. Q. R.*; 川北至信; 伊藤晋一*

Journal of Alloys and Compounds, 695, p.426 - 432, 2017/02

https://doi.org/10.1016/j.jallcom.2016.10.266

被引用回数：5 パーセンタイル：23.14(Chemistry, Physical)

Inelastic X-ray scattering (IXS) was performed on polycrystalline Mg $_{97}$ ZnY and Mg $_{85}$ ZnY alloys with synchronized long-period stacking ordered (LPSO) phase for investigating the impurity effects in the microscopic elastic properties. Inelastic neutron scattering (INS) was also carried out on the former alloy. LA modes were clearly observed in the IXS spectra of both the LPSO alloys, while TA modes can mainly be detected in the second Brillouin zone. Broader inelastic signals and larger quasielastic peaks are characteristic due to the phonon scattering by the Zn/Y impurities. Only the TA excitation energies increase by adding the impurities, which indicates a harder stiffness of the bond angles relating to the L1-type clusters in the LPSO alloys. New dispersion-less excitation modes are observed at about 10 meV by adding the Zn/Y impurities. By comparing with the INS data, the contributions of the impurities to these excitations are discussed using differences in the scattering cross-sections between neutrons and X-rays.

論文

Numerical simulation on molten metal collision behavior using SPH method combined with fractal analysis on morphology of stacking pattern

二川正敏; 筒井喜平*; 粉川広行; 直江崇

Key Engineering Materials, 715, p.203 - 209, 2016/11

https://doi.org/10.4028/www.scientific.net/KEM.715.203

世界的関心の寄せられる様々な科学技術を展開しうる大強度陽子加速器施設では、加速器から出射されるMW級の大強度陽子線に耐えつつ、効率よく2次粒子を生成する標的が要求される。固体金属標的は、大強度の陽子線が入射することによって非常に高い熱流束が負荷され、場合によっては瞬時に溶融することが推測される。実際、J-PARC(Japan Proton Accelerator Research Complex)では、金の固体標的が局所的に溶融し、溶融金が噴出する事象が生じた。溶融金ジェットは真空を隔てるフランジ板に衝突して飛散すると共に、一部はフランジ板に付着した。この挙動を粒子法による数値解析で再現し、フランジ板上の付着痕の様相と衝突速度との相関について、フラクタル解析を導入して定量評価を試みた。その結果、フラクタル次元は衝突速度に依存し、局所衝撃力や飛散挙動を評価する指標として有効であることが分かった。

論文

Effect of magnetism on lattice dynamics in SrFeAs using high-resolution inelastic X-ray scattering

村井直樹*; 福田竜生; 小林達也*; 中島正道*; 内山裕士*; 石川大介*; 筒井智嗣*; 中村博樹; 町田昌彦; 宮坂茂樹*; et al.

Physical Review B, 93(2), p.020301_1 - 020301_5, 2016/01

https://doi.org/10.1103/PhysRevB.93.020301

被引用回数：7 パーセンタイル：31.62(Materials Science, Multidisciplinary)

Phonon spectra of detwinned SrFeAs crystals, as measured by inelastic X-ray scattering, show clear anisotropyaccompanying the magnetostructural transition at 200 K. We model the mode splitting using magnetic DFT calculations, including a phenomenological reduction in force-constant anisotropy that can be attributed to magnetic fluctuations. This serves as a starting point for a general model of phonons in this material applicable to both the antiferromagnetically ordered phase and the paramagnetic phase. Using this model, the measured splitting in the magnetic phase below T, and the measured phonon linewidth, we set a lower bound on the mean magnetic fluctuation frequency above T at 210 K.

論文

Mssbauer spectroscopy of actinide compounds

筒井智嗣

Mssbauer Effect Reference and Data Journal, 38(4), p.105 - 111, 2015/06

アクチノイド化合物のメスバウアー分光は日本でも海外でも実施可能な施設は限られる。日本におけるアクチノイドのメスバウアー分光の研究は1990年代に先端基礎研究センターにおいて開始された。本稿では、1996年に先端基礎研究センターで開始されたU-238メスバウアー分光及び東北大学金属材料研究所で開始されたネプツニウム金属間化合物のメスバウアー分光に関する研究成果について纏めた。また、これらのアクチノイドのメスバウアー分光の研究成果のレビューを行うとともに、その発展に寄与された故那須三郎阪大名誉教授の貢献に関してまとめたものである。

論文

X-ray absorption spectroscopy and novel electronic properties in heavy fermion compounds YbT $_{2}$ Zn $_{20}$ (T: Rh and Ir)

本多史憲*; 広瀬雄介*; 三宅厚志*; 水牧仁一朗*; 河村直己*; 筒井智嗣*; 綿貫徹; 渡辺真仁*; 竹内徹也*; 摂待力生*; et al.

Journal of Physics; Conference Series, 592(1), p.012021_1 - 012021_5, 2015/03

https://doi.org/10.1088/1742-6596/592/1/012021

被引用回数：3 パーセンタイル：70.08(Physics, Atomic, Molecular & Chemical)

重い電子系化合物YbT $_{2}$ Zn $_{20}$ (T: Rh and Ir)について、X線吸収分光法によりYb価数観察を行った。いずれの化合物でもYb価数は温度依存性を示し、約100K以下で冷却とともにYb価数が減少する変化が見られた。これは、同型化合物であるYbCo $_{2}$ Zn $_{20}$ において温度依存性が見られないこととは対照的な結果である。

論文

Zirconia membrane ECP electrode for water chemistry experiments in the JMTR

塙悟史; 端邦樹; 柴田晃; 知見康弘; 笠原茂樹; 筒井伸行*; 岩瀬彰宏*; 西山裕孝

Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10

腐食電位(ECP)センサーは照射下における材料の腐食環境を測定できる唯一の計測器である。高い耐久性を有するECPセンサーをJMTRで実施する水化学実験で使用するために、ジルコニア隔膜型ECPセンサーを開発した。ジルコニア及び金属筐体の材料選定とそれらの最適な組み合わせを検討し、ジルコニアにはイットリア安定化ジルコニアを、金属筐体には42合金を採用した。また、ジルコニア/金属の接合部への欠陥の発生を防止するために金属筐体の構造最適化を図った。ECPセンサーの性能はオートクレーブで評価し、理論的に求まる電位に準ずる電極電位を示すとともに電極電位は水質環境の変化に対しても安定であることを確認した。また、ECPセンサーへの照射影響としてジルコニアへの照射誘起伝導の影響を評価し、ジルコニアに照射誘起伝導は生じるもののECPセンサー機能には影響を及ぼさないことを示した。