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Journal Articles

Pyroelectric power generation from the waste heat of automotive exhaust gas

Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Sakamoto, Tomokazu*; Kawasaki, Takuro; Fukuda, Tatsuo; Sekino, Toru*; Nakayama, Tadachika*; Takeda, Masatoshi*; et al.

Sustainable Energy & Fuels (Internet), 4(3), p.1143 - 1149, 2020/03

 Times Cited Count:2 Percentile:32.54(Chemistry, Physical)

Journal Articles

Research on hydrogen safety technology utilizing the automotive catalyst

Ono, Hitomi*; Takenaka, Keisuke*; Kita, Tomoaki*; Taniguchi, Masashi*; Matsumura, Daiju; Nishihata, Yasuo; Hino, Ryutaro; Reinecke, E.-A.*; Takase, Kazuyuki*; Tanaka, Hirohisa*

E-Journal of Advanced Maintenance (Internet), 11(1), p.40 - 45, 2019/05

Journal Articles

Electrochemical adsorption on Pt nanoparticles in alkaline solution observed using in situ high energy resolution X-ray absorption spectroscopy

Kusano, Shogo*; Matsumura, Daiju; Ishii, Kenji*; Tanaka, Hirohisa*; Mizuki, Junichiro*

Nanomaterials (Internet), 9(4), p.642_1 - 642_14, 2019/04

 Times Cited Count:0 Percentile:100(Nanoscience & Nanotechnology)

Journal Articles

Electrical and crystallographic study of an electrothermodynamic cycle for a waste heat recovery

Kim, J.*; Yamanaka, Satoru*; Nakajima, Akira*; Kato, Takanori*; Kim, Y.*; Fukuda, Tatsuo; Yoshii, Kenji; Nishihata, Yasuo; Baba, Masaaki*; Takeda, Masatoshi*; et al.

Advanced Sustainable Systems (Internet), 2(11), p.1800067_1 - 1800067_8, 2018/11

 Times Cited Count:1 Percentile:82.92(Green & Sustainable Science & Technology)

Journal Articles

Temperature stability of PIN-PMN-PT ternary ceramics during pyroelectric power generation

Moro, Takuya*; Kim, J.*; Yamanaka, Satoru*; Murayama, Ichiro*; Kato, Takanori*; Nakayama, Tadachika*; Takeda, Masatoshi*; Yamada, Noboru*; Nishihata, Yasuo; Fukuda, Tatsuo; et al.

Journal of Alloys and Compounds, 768, p.22 - 27, 2018/11

 Times Cited Count:7 Percentile:35.32(Chemistry, Physical)

Journal Articles

Negative correlation between electrical response and domain size in a Ti-composition-gradient Pb[(Mg$$_{1/3}$$Nb$$_{2/3}$$)$$_{1-x}$$Ti$$_{x}$$]O$$_{3}$$ crystal near the morphotropic phase boundary

Shimizu, Daisuke*; Tsukada, Shinya*; Matsuura, Masato*; Sakamoto, Junya*; Kojima, Seiji*; Namikawa, Kazumichi*; Mizuki, Junichiro; Owada, Kenji

Physical Review B, 92(17), p.174121_1 - 174121_5, 2015/11

 Times Cited Count:8 Percentile:57.71(Materials Science, Multidisciplinary)

The phase diagram and the relationship between the crystal coherence length and electrical response of Pb[(Mg$$_{1/3}$$Nb$$_{2/3}$$)$$_{1-x}$$Ti$$_{x}$$]O$$_{3}$$ (PMN-xPT) near the morphotropic phase boundary (MPB) have been precisely investigated using a single crystal with a Ti composition gradient by synchrotron X-ray diffraction and inelastic light scattering at room temperature. The crystal has two boundaries at Ti compositions of 29.0 mol% and 34.7 mol% which correspond to the phase boundaries between the monoclinic B (MB) and C (MC) phases and between the MC and tetragonal (T) phases, respectively. It is shown that there is a strong negative correlation between the electrical response and the crystal coherence length at the sub-$$mu$$m scale. The results are explained by the size effects of domains near the MPB.

Journal Articles

Effects of randomness and frustration on the relaxor nature in Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$

Owada, Kenji

Nippon Kessho Gakkai-Shi, 54(3), p.147 - 154, 2012/06

It is well known that B-site randomness contributes to the appearance of relaxor phenomena in the lead-based complex perovskite Pb(B'B'')O$$_{3}$$. But the microscopic mechanism of the effect of B-site randomness on the systems has not been understood yet. Among the Pb(B'B'')O$$_{3}$$ systems, Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) has drawn much attention because it can be in the antiferroelectric (AFE), ferroelectric (FE), or relaxor state depending on B-site randomness. We review the recent progress in our understanding of the effect of B-site randomness on PIN from the experimental viewpoint. As a conclusion of the arguments, we also introduce the frustration mechanism in Pb(B'B'')O$$_{3}$$.

Journal Articles

Effect of B-site randomness on the antiferroelectric/relaxor nature of the ground state; Inelastic X-ray scattering study of Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$

Owada, Kenji; Fukuda, Tatsuo; Mizuki, Junichiro; Hirota, Kazuma*; Terauchi, Hikaru*; Tsutsui, Satoshi*; Baron, A. Q. R.*; Owa, Hidehiro*; Yasuda, Naohiko*

Journal of the Korean Physical Society, 59(3), p.2509 - 2514, 2011/09

 Times Cited Count:2 Percentile:77.51(Physics, Multidisciplinary)

Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) can be antiferroelectric (AFE), ferroelectric (FE) or a relaxor depending upon the perovskite B-site randomness. Orderd PIN (O-PIN, without B-site randomness) is supposed to be an ideal system of lead-based complex perovskite Pb(B'B'')O$$_{3}$$ and expected to give us a clear picture of the AFE/relaxor nature of the ground state by the B-site randomness. We studied the dynamics of O-PIN by inelastic X-ray scattering. The quasielastic (QE) scattering shows the critical slowing down and the transverse acoustic (TA) mode shows the softening towards $$T_{rm N}$$. On the other hand, the transverse optic (TO) mode shows the softening toward low temperature with no clear anomaly at $$T_{rm N}$$. These results represent that the antiferroelectric (AFE) phase transition is associated with the TA and the origin of the QE scattering, while ferroelectric correlation does exist behind the AFE ordering. The effect of B-site randomness is finally discussed on the basis of the results.

Journal Articles

Antiferroelectric correlation in relaxor Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ and ferroelectric correlation in antiferroelectric Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro; Owa, Hidehiro*; Yasuda, Naohiko*

Transactions of the Materials Research Society of Japan, 34(1), p.19 - 22, 2009/03

Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) can be antiferroelectric (AFE), ferroelectric (FE) or a relaxor depending upon the perovskite B-site randomness. This is characterized by measurements of dielectric response, which shows behavior that is usually clearly in one of those three classes. In contrast, X-ray scattering studies suggest the presence of AFE correlation in the relaxor state and FE in AFE state. Weak phonon softening at zone boundary in relaxor state shows that the AFE correlation intrinsically exists in PIN, as does the corresponding elastic scattering at (${it h}$/2 ${it k}$/2 0), while weak diffuse scattering around 333 Bragg reflection appears in AFE state suggesting FE correlation. These results will support our previous speculation that the AFE and FE correlations coexist in PIN (K. Owada ${it et al}$., Phys, Rev. B${bf 77}$ 094136 (2008)). Such a coexistence or competition is widely seen in the perovskite relaxor and the coexistence of FE and AFE correlations is essential for generating relaxor state.

Journal Articles

Intrinsic ferroelectric instability in Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ revealed by changing B-site randomness; Inelastic X-ray scattering study

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro; Owa, Hidehiro*; Yasuda, Naohiko*

Physical Review B, 77(9), p.094136_1 - 094136_8, 2008/03

 Times Cited Count:16 Percentile:39.67(Materials Science, Multidisciplinary)

Antiferroelectric (AFE), ferroelectric (FE) or relaxor states can appear in Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) depending upon the perovskite B-site randomness. We studied the effects of this randomness on the dynamics of PIN by high resolution inelastic X-ray scattering using ordered PIN (AFE) and disordered PIN (relaxor) single crystals. We have found a clear softening of a transverse optic mode at the $$Gamma$$ point in both the samples, indicating a robust and intrinsic ferroelectric instability regardless of the actual ground state. We interpret that AFE is stabilized only when In and Nb ions are spatially ordered enough to overwhelm the FE instability. As the B-site randomness becomes larger, AFE is suppressed and the hidden FE state starts appearing. Ultimately, the randomness begins to predominate over the development of FE regions and blocks a long range FE order, which we believe yields polar nanoregions resulting in relaxor behaviors.

Journal Articles

Spatial distribution of the B-site inhomogeneity in an ${it as-grown}$ Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ single crystal studied by a complementary use of X-ray and neutron scatterings

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Owa, Hidehiro*; Yasuda, Naohiko*

Journal of the Physical Society of Japan, 75(2), p.024606_1 - 024606_6, 2006/12

 Times Cited Count:6 Percentile:55.88(Physics, Multidisciplinary)

Structural properties of ${it as-grown}$ Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) single crystals at room temperature (RT) were investigated by X-ray and neutron scattering techniques, taking much account of the difference in the penetration depth and spatial resolution of X-rays and those of neutrons. A strong diffuse scattering was observed by X-ray while h/4, k/4, 0 superlattice reflections were found by neutron, indicating a relaxor state in the outer-layer of the crystal and an antiferroelectric (AFE) state in the bulk. The phonon dispersion was measured for the first time for the PIN series. Two transverse optic (TO1 and TO2) modes were clarified near the zone center though neither water-fall behavior nor folding of phonon branches was confirmed. We have thus concluded that a major part of the ${it as-grown}$ PIN crystal at RT is ferroelectric (FE). These results imply that the $$B$$-site chemical ordering, i.e. inhomogeneity, which controls the structural properties of PIN, is unevenly distributed throughout the crystal. We speculate that small AFE grains coexist with the FE matrix while the outer-layer is in a relaxor state in the ${it as-grown}$ PIN.

Oral presentation

X-ray and neutron scattering study of Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Owa, Hidehiro*; Yasuda, Naohiko*

no journal, , 

no abstracts in English

Oral presentation

Intrinsic ferroelectric instability in Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$; Inelastic X-ray scattering in control of the B-site randomness

Owada, Kenji; Hirota, Kazuma*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A.*; Mizuki, Junichiro; Terauchi, Hikaru*; Owa, Hidehiro*; Yasuda, Naohiko*

no journal, , 

Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$(PIN) varies among antiferroelectric (AFE), ferroelectric (FE) and relaxor states depending upon the perovskite B-site randomness. We studied the effects of this randomness on the dynamics of PIN by high resolution inelastic X-ray scattering using ordered PIN (AFE) and disordered PIN (relaxor) single crystals. We have found a clear softening of a transverse optic mode at the $$gamma$$ point in both the samples, indicating a robust and intrinsic ferroelectric instability regardless of the actual ground state. We interpret that AFE is stabilized only when In and Nb ions are spatially ordered enough to overwhelm the FE instability. As the B-site randomness becomes larger, AFE is suppressed and the FE ground state starts appearing. Ultimately, the randomness competes with the development of FE regions and blocks a long range FE order, which we believe yields polar nanoregions resulting in relaxor behaviors.

Oral presentation

Intrinsic ferroelectric instability in Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ revealed by changing B-site randomness; Inelastic X-ray scattering study

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro; Owa, Hidehiro*; Yasuda, Naohiko*

no journal, , 

no abstracts in English

Oral presentation

Intrinsic ferroelectric instability in Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ revealed by changing B-site randomness

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro; Owa, Hidehiro*; Yasuda, Naohiko*

no journal, , 

Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ (PIN) varies among antiferroelectric (AFE), ferroelectric (FE) and relaxor states depending upon the perovskite B-site randomness. We studied the effects of this randomness on the dynamics of PIN by high resolution inelastic X-ray scattering using ordered PIN (AFE) and disordered PIN (relaxor) single crystals. We have found a clear softening of a transverse optic mode at the $$Gamma$$ point in both the samples, indicating a robust and intrinsic ferroelectric instability regardless of the actual ground state. We interpret that AFE is stabilized only when In and Nb ions are spatially ordered enough to overwhelm the FE instability. As the B-site randomness becomes larger, AFE is suppressed and the FE ground state starts appearing. Ultimately, the randomness competes with the development of FE regions and blocks a long range FE order, which we believe yields polar nanoregions resulting in relaxor behaviors.

Oral presentation

Ferroelectric and antiferroelectric correlations in antiferroelectric Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$ studied by X-ray diffraction

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Owa, Hidehiro*; Yasuda, Naohiko*

no journal, , 

no abstracts in English

Oral presentation

Inelastic X-ray scattering study of Ordered-Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_{3}$$

Owada, Kenji; Hirota, Kazuma*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro; Terauchi, Hikaru*; Owa, Hidehiro*; Yasuda, Naohiko*

no journal, , 

no abstracts in English

Oral presentation

Heterophase fluctuation in relaxor ferroelectrics PZN-9%PT

Owada, Kenji; Namikawa, Kazumichi*; Matsushita, Mitsuyoshi*; Mizuki, Junichiro*

no journal, , 

no abstracts in English

Oral presentation

Relationship between domain fluctuation and dielectric constant in relaxor ferroelectrics PZN-9%PT studied by coherent X-ray scattering

Owada, Kenji; Namikawa, Kazumichi*; Matsushita, Mitsuyoshi*; Mizuki, Junichiro*

no journal, , 

It is generally known that the temperature dependence of the dielectric constants of relaxor ferroelectrics near morphotropic phase boundary (MPB) shows a cooling-rate dependence. This is due to a domain fluctuation across a tetragonal-to-rhombohedral phase transition. In this paper, we focus on the tetragonal-to-rhombohedral phase transition (T$$_{RT}sim$$300 K) in relaxor ferroelectrics PZN-9%PT, which is very close to MPB. We have simultaneously measured the frequency-dependent dielectric constants and the coherent X-ray scattering directly reflecting a domain configuration. The results directly show an effect of the domain fluctuation on a low-frequency dielectric permittivity. These results should strongly relates to the cooling-rate dependence on the temperature dependence of the dielectric constants.

Oral presentation

X-ray irradiation effect of KTaO$$_{3}$$; Measurement of thermally stimulated electrical currents

Nishihata, Yasuo; Nakanishi, Yusuke*; Sakaue, Kiyoshi*

no journal, , 

no abstracts in English

22 (Records 1-20 displayed on this page)