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Your search keyword '"Yamaguchi, Toshihisa"' showing total 153 results
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153 results on '"Yamaguchi, Toshihisa"'

5. Low temperature dielectric and magnetic properties of Fe-ion-doped SrTiO3

Author

Fujishita, Hideshi, Arai, Yuya, Okamoto, Hiroyuki, and Yamaguchi, Toshihisa

Subjects
Vendik model, Condensed Matter::Materials Science, Fe-ion-doped STO, Physics::Optics, Magnetic property, Dielectric constant, Quantum paraelectrics
Abstract

Dielectric and magnetic properties of SrTi1−xFexO3 were measured for a single crystal sample (x=0.0032) and a ceramic sample (x=0.02). Temperature dependences of the dielectric constants were analyzed on the basis of a Vendik's formula, which describes a quantum paraelectric state accurately. A small amount of Fe impurities in the single crystal does not affect the characteristic temperatures of the dielectric properties, but does affect the quality of the crystal. This change in quality causes a large change in the dielectric constant of the quantum paraelectric state. The temperature dependence of the dielectric constant of the quantum paraelectric state of the ceramic sample is different from that of the single crystal not only quantitatively, but also qualitatively. The magnetic susceptibilities obey the typical Curie law, though a deviation of the Curie law was observed below 5 K for x=0.02. Crystals with the both concentrations remain in paramagnetic states at 2.5 K. The magnetic properties of SrTi1−xFexO3 can, in all likelihood, be explained by the orientation effect of free Fe3+ions. In addition, an antiferroelectric interaction suggested for EuTiO3 by an analysis of dielectric constants based on a Barrett's formula was turned out to be unnecessary following analysis of the same data based on the Vendik's formula., Embargo Period 12 months

Published
2017

7. 超伝導磁気浮上走行体の速度測定

Author

Takashige, Masaaki, Suguro, Riko, Hashimoto, Akemi, and Yamaguchi, Toshihisa

Subjects
磁気浮上, magnetic levitation, flux pinning, Condensed Matter::Superconductivity, superconductivity, Meissner effect, 磁束のピン止め, マイスナー効果, 超伝導
Abstract

By Meissner effect and the magnetic flux pinning effect, superconductor can levitate and run on a magnetic rail. In this study, an experiment to measure the velocity of the superconductive body was performed, which runs without contact on the rail consisting of an array of neodymium or ferrite magnets. On such magnetic rails having several different gradients, the sliding velocity of the superconductive body was measured. From results, the relation between the friction and the velocity of superconductor were discussed. The brief summary of physics for superconductivity, in particular for magnetic properties, was also given.

Published
2016

10. Inelastic Neutron Scattering Study of Ferroelectric Phase Transition in Lithium Heptagermanate (Li(2)Ge(7)O(15))

Author

Takeda, Mitsuo W., Noda, Yukio, and Yamaguchi, Toshihisa

Subjects
Ferroelectrics, Soft phonon mode, Li(2)Ge(7)O(15), Critical slowing-down, Inelastic neutron scattering
Abstract

Phonon dispersions in ferroelectric lithium heptagermanate Li(2)Ge(7)O(15) (LGO) were measured by inelastic neutron scattering in the vicinity of the transition temperature T(C) = 283.5 K. The (300) reflections show more pronounced temperature dependence than the (500) reflections. The energy of a peak corresponding to the Brillouin zone-center phonon, around 0.5 meV at 297.0 K, decreases as the temperature decreases. Then, this inelastic component disappears into the central component at 288.0 K, just above T(C). The present phonon shows the typical soft mode feature and shows good accordance with the B(1u) mode observed by hyper-Raman and FTIR measurements. It is confirmed that the ferroelectric phase transition in LGO is associated with the soft optical phonon at the zone center. Moreover, elastic diffuse scattering is observed below 0.1 meV. This implies that there exists a critical phenomenon at energies below than 0.1 meV., Article, FERROELECTRICS. 412(0):45-51 (2011)

Published
2011

30. Dielectric Properties of Crystallization Process from Amorphous Bi4Ti3O12

Author

Masaaki Takashige, Masaaki Takashige, primary, Sinichi Hamazaki, Sinichi Hamazaki, additional, Ryou Yoshida, Ryou Yoshida, additional, Masayoshi Kokubun, Masayoshi Kokubun, additional, Fuminao Shimizu, Fuminao Shimizu, additional, Toshihisa Yamaguchi, Toshihisa Yamaguchi, additional, Min-Su Jang, Min-Su Jang, additional, and Seiji Kojima, Seiji Kojima, additional

Published
2001
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46. Dielectric and phase transitional properties of Rb2ZnI4and its mixed systems at low temperatures

Author

Shibata, Ryo, Muraki, Ryota, Yamaguchi, Toshihisa, and Takashige, Masaaki

Abstract

The temperature dependence of the dielectric constant of Rb2ZnI4shows two peak anomalies: one at 4 K and the other at 62 K. To study this, we prepared crystals of the mixed system Rb2Zn1-xCdxI4from the melt by using the Czochralski method. Dielectric constant and spontaneous polarization measurements were performed on crystals from the mixed system. The phase diagram of Rb2Zn1-xCdxI4was completed over a full range of concentrations x. The result was compared with the already-reported result for (Rb1-xKx)2ZnI4.

Published
2015
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50. Rb2ZnCl4group ferroelectrics

Author

Sawada, Shozo, primary, Takashige, Masaaki, additional, Yamaguchi, Toshihisa, additional, Shimizu, Fuminao, additional, and Suzuki, Haruhiko, additional

Published
1992
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