研究者詳細 - 寺西　貴志

論文 - 寺西　貴志

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Complex Conductivity Using Wideband Spectroscopy for Yttria/Ytterbia-Stabilized Zirconia Ceramics 査読

Takashi Teranishi, Kosuke Shimizu, Naoki Akiyama, Hidetaka Hayashi, Akira Kishimoto, Kazuhiro Fujimori

JAPANESE JOURNAL OF APPLIED PHYSICS 51 ( 1 ) 2012年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPAN SOC APPLIED PHYSICS

Complex conductivity wideband spectra from 10(-1) to 10(14) Hz (100 THz) were determined for 8 mol% yttria-stabilized zirconia (8YSZ) and 8 mol% ytterbia-stabilized zirconia (8YbSZ) ceramics. The contributions of electrolyte-electrode interfaces, grain boundaries, intragrain ion-hopping, and optical phonons were quantified to relate the microscopic conduction behavior to the overall conductivity. Intrinsic conductivity was mostly governed by ion-hopping. For both 8YSZ and 8YbSZ, ion-hopping followed the universal dielectric response (UDR) for broadband frequencies except for the phonon dispersion frequencies. The higher overall conductivities of the 8YbSZ ceramics compared to the 8YSZ ones were attributed to differences in the UDR contributions. The dominant factor determining the difference in the intrinsic conductivity in broadband frequencies from direct current (DC) to microwave between the 8YSZ and 8YbSZ ceramics was the DC conductivity due to UDR, sigma(dc), where sigma(dc(8YbSZ)) > sigma(dc(8YSZ)). Other parameters in the UDR and the optical parameters did not greatly influence the intrinsic conductivities. (C) 2012 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.51.011102

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Broadband spectroscopy of the complex conductivity of polycrystalline yttria-stabilized zirconia 査読

Takashi Teranishi, Hidetaka Hayashi, Akira Kishimoto, Takaaki Tsurumi

MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS 177 ( 1 ) 69 - 73 2012年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Broadband conductivity spectra from 100 to 10(14) Hz (100 THz) were acquired for yttria-stabilized zirconia (10 mol% Y(2)O(3)-doped ZrO(2), 10YSZ) to quantify contributions from conduction due to the electrolyte electrode interface, grain boundaries, universal dielectric response (UDR), and optical phonons. The UDR contribution governed the intrinsic conductivity at all frequencies except specific frequencies in the terahertz range, where phonon contributions governed conductivity for both ceramics and single crystals. UDR parameters sigma(0) and sigma(dc), increased with increasing temperature, resulting in increased microwave conductivity. The complex conductivity converged at frequencies of hundreds of gigahertz due to a decrease in the power-law constants, with increasing temperature. The optical phonon contribution to the total conductivity, due to an increase in the damping factor gamma(1TO) with increasing temperature, was small, while the phonon-mode frequency omega(1TO) affected the microwave conductivity of 10YSZ. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.mseb.2011.09.039

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Complex Conductivity Using Wideband Spectroscopy for Yttria/Ytterbia-Stabilized Zirconia Ceramics 査読

Japanese Journal of Applied Physics 51 011102 2011年12月

Broadband spectroscopy of the complex conductivity of polycrystalline yttria-stabilized zirconia 査読

Materials Science and Engineering B 177 69 - 73 2011年10月

Effect of varying the ratio of matrix/dispersoid particle size on the piezoresistivity of alumina/carbon-black composite ceramics 査読

Akira Kishimoto, Yuto Takagawa, Takashi Teranishi, Hidetaka Hayashi

MATERIALS LETTERS 65 ( 14 ) 2197 - 2200 2011年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Alumina/carbon-black composite ceramics with different percolation thresholds were fabricated by changing the size ratio of constituent particles. The dependence of resistivity on pressure was established for each sample. The compositional dependence of resistivity can be explained by percolation theory. The percolation threshold decreases with increasing alumina/carbon-black particle size ratio. The pressure dependence of the resistivity increases as the composition approaches the percolation threshold. When the relative composition at the percolation threshold is fixed, the sensitivity increases with increasing matrix/dispersoid initial particle size ratio. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2011.04.042

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Effect of varying the ratio of matrix/dispersoid particle size on the piezoresistivity of alumina/carbon-black composite ceramics 査読

Materials Letters 65 2197 - 2200 2011年4月

Size effect and domain-wall contribution of barium titanate ceramics 査読

Takuya Hoshina, Yoichi Kigoshi, Saki Hatta, Takashi Teranishi, Hiroaki Takeda, Takaaki Tsurumi

Ferroelectrics 402 ( 1 ) 29 - 36 2010年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Barium titanate (BaTiO3) ceramics with various grain sizes from 0.7 to 13 μm were prepared by a conventional sintering method and a two-step sintering method. The permittivity of the BaTiO3 ceramics with an average grain size of 1.1 μm exhibited a maximum around 8,000. By ultrawide range dielectric spectroscopy, the domain-wall contribution to the permittivity was investigated. For the BaTiO3 ceramics with grain sizes over 1 μm, the dipole and ionic polarizabilities were enhanced by the high domain density. In contrast, for the BaTiO3 ceramics with grain sizes below 1 μm, these polarizabilities were weakened. Copyright © 2010 Taylor & Francis Group, LLC.

DOI： 10.1080/00150191003697179

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Effects of oxygen vacancies and grain sizes on the dielectric response of BaTiO3 査読

Applied Physics Letters 97 212907-1 - 212907-3 2010年11月

Analysis of polarization behavior in relaxation of BaTiO<inf>3</inf>-based ferroelectrics using wideband dielectric spectroscopy 査読

Takashi Teranishi, Takuya Hoshina, Hiroaki Takeda, Takaaki Tsurumi

IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 57 ( 10 ) 2118 - 2126 2010年10月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Wideband dielectric spectra from the kilohertz to terahertz range are discussed for BaTiO3-based ferroelectrics. Ceramics of BaTiO3 (BT), Ba0.6Sr0.4TiO3 (BST-0.6), and BaZr0.25Ti0.75O3 (BZT-0.25) were selected as normal ferroelectrics, ferroelectrics with diffuse phase transition (DPT ferroelectrics), and relaxor ferroelectrics, respectively. The variation of ionic polarization in both BT and BST-0.6 ceramics with temperature could be explained by the softening of the soft phonon mode. In BZT-0.25, a permittivity anomaly at the dielectric maximum temperature (Tm) at low frequencies is not attributed to the softening of the soft phonon mode, but originates from the permittivity derived from the εdipole polarization (dipole). Relaxor behavior in BZT-0.25 is derived from the increase in the depression of εdipole on cooling across the Tm with increasing frequency. In εdipole polarization, BT, BST- 0.6, and BZT-0.25 all exhibited a similar tendency of εdipole above the Curie temperature (Tc) and Tm. However, behavior of εdipole below the Tc can be explained by the ferroelectric domains in BT, whereas the variation of εdipole below the Tm could be explained by growth process of polar nanoregions (PNRs) in BST-0.6 and BZT-0.25. Regarding this, BT can be distinguished from BST-0.6 and BZT-0.25. Relaxation in BT could be interpreted as successive change in polarization mechanism from normal ferroelectrics to relaxor ferroelectrics via DPT ferroelectrics. © 2010 IEEE.

DOI： 10.1109/TUFFC.2010.1667

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Analysis on Dipole Polarization of BaTiO3-based Ferroelectric Ceramics by Raman Spectroscopy 査読

Journal of the Ceramic Society of Japan 118 679 - 682 2010年8月

Analysis on dipole polarization of BaTiO3-based ferroelectric ceramics by Raman spectroscopy 査読

Takashi Teranishi, Naohiro Horiuchi, Takuya Hoshina, Hiroaki Takeda, Takaaki Tsurumi

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 118 ( 1380 ) 679 - 682 2010年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

Analysis of asymmetric Raman line shape disclosed the variation of phonon correlation length in A(1)(3TO) mode, L-A1(3TO), with temperature in the ceramics of BaTiO3 (BT), Ba0.6Sr0.4TiO3 (BST-0.6) and BaZr0.25Ti0.75O3 (BZT-0.25), namely normal ferroelectrics, ferroelectrics with diffuse phase transition (DPT ferroelectrics) and relaxor ferroelectrics, respectively. In BT, L-A1(3TO) exhibited steep increase at the Curie temperature (T-c) on cooling. This is attributed to the formation of the ferroelectric domains at the T-c. Both BST-0.6 and BZT-0.25 showed gradual increase in L-A1(3TO) on cooling across the dielectric maximum temperature (T-m), indicating the continuous increase in the average size of the polar nanoregions (PNRs). Normal ferroelectrics can be distinguished from DPT and relaxor ferroelectrics in this point. L-A1(3TO) of BZT-0.25 was longer than that of BST-0.6 near the T-m. This suggests the size of PNRs in BZT-0.25 is larger than that in BST-0.6. Huge dipole polarization of BZT-0.25, giving rise to the strong relaxor behavior, could be originated from the contribution of the large PNRs near the T-m. DPT ferroelectrics can be also differentiated from relaxor ferroelectrics in terms of the average size of PNRs. (C) 2010 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.118.679

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Wide Band Dielectric Spectroscopy at Ferroelectric Phase Transition of BaTiO3 Ceramics 査読

Japanese Journal of Applied Physics 49 041506-1 - 041506-4 2010年4月

Dielectric Properties of Barium Titanate Ceramics with Nano-Sized Domain 査読

Yoichi Kigoshi, Saki Hatta, Takashi Teranishi, Takuya Hoshina, Hiroaki Takeda, Osamu Sakurai, Takaaki Tsururni

Key Engineering Materials (ELECTROCERAMICS IN JAPAN XIII) 445 27 - 30 2010年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：TRANS TECH PUBLICATIONS LTD

Barium titanate (BaTiO3) ceramics with various grain sizes from 0.7 to 13 mu m on average were prepared by a conventional sintering method, a two-step sintering method and a rate controlled two-step sintering method. The permittivity of the ceramics was increased with decreasing grain size to 1.1 mu m on average. However, the permittivity of the ceramics was decreased when the grain size was below 1 mu m. The field emission scanning electron microscope (FE-SEM) observations revealed that the 900 domain width decreased with decreasing the grain size. By ultrawide range dielectric spectra from kHz to THz range of the BaTiO3 ceramics, the domain contribution to the permittivity was investigated. For the BaTiO3 ceramics with grain sizes over 1 mu m, the dipole polarizability and the ionic polarizability were enhanced by high domain-wall density. In contrast, for the BaTiO3 ceramics with grain sizes below 1 mu m, these polarizabilities were weakened.

DOI： 10.4028/www.scientific.net/KEM.445.27

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Wide Range Dielectric Spectroscopy of Barium Strontium Titanate Ceramics 査読

Takashi Teranishi, Takuya Hoshina, Hiroaki Takeda, Takaaki Tsurumi

Key Engineering Materials (ASIAN CERAMIC SCIENCE FOR ELECTRONICS III AND ELECTROCERAMICS IN JAPAN XII) 421-422 273 - 276 2010年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：TRANS TECH PUBLICATIONS LTD

Wide band dielectric spectroscopy was applied from kHz to THz region for the analysis of both the ionic and the dipole polarization in Ba(0.6)Sr(0.4)TiO(3) ceramics. The dielectric permittivity above the dielectric maximum temperature (T(m)) is mostly dominated by the ionic polarization, while that below T(m) is governed by the dipole polarization. Dielectric permittivity given by the dipole polarization increased and the relaxation frequency decreased with decreasing temperature. These phenomena are related to a increase of the size of polar nanoregions (PNRs).

DOI： 10.4028/www.scientific.net/KEM.421-422.273

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Wide Range Dielectric Spectroscopy on Perovskite Dielectrics 査読

Materials Science and Engineering: B 161 55 - 60 2009年4月

Polarization Behavior in Diffuse Phase Transition of BaxSr1−xTiO3 Ceramics 査読

Journal of Applied Phyics 105 054111-1 - 054111-5 2009年3月

Ultrawideband Dielectric Spectroscopy of BaZrxTi1−xO3 Ceramics and Its Microscopic Mechanism of Polarization 査読

Journal of Applied Phyics 105 114102-1 - 14102-4 2009年1月

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