Faculty Profiles - TERANISI Takasi

Papers - TERANISI Takasi

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Relationship Between Phonon Parameters and Oxygen Ion Conductivity for Al-Yb Co-doped Zirconia Reviewed

Takashi Teranishi, Nami Matsubara, Hidetaka Hayashi, Akira Kishimoto

ELECTROCERAMICS IN JAPAN XVI 582 107 - 110 2014

Language：English Publishing type：Research paper (international conference proceedings) Publisher：TRANS TECH PUBLICATIONS LTD

The relationship between the optical phonon parameters and the oxygen ion conductivities were investigated for Al-Yb co-doped zirconia ceramics. Intrinsic intragrain ion conductivity, sigma(dc) decreased with increasing Al loading into ytterbia-stabilized zirconia, while the damping parameter of the lattice vibration, gamma(1TO), increased. This phenomenon agreed with findings of our previous study, which revealed a relationship between the sigma(dc), and the gamma(1TO) for zirconia-based ion conductors.

DOI： 10.4028/www.scientific.net/KEM.582.107

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Maintaining the mechanical strength of La-, Y-co-substituted zirconia porous ceramics through the superplastically foaming method Reviewed

Akira Kishimoto, Masanori Okada, Takashi Teranishi, Hidetaka Hayashi

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 581 98 - 103 2013.10

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

The superplastically foaming method was adopted to make closed-pore inclusive zirconia-based ceramics. Lanthanum oxide was added to monoclinic or tetragonal yttria-stabilised zirconia to reduce the thermal conductivity of the matrix. Sintering and superplastic deformation led to a solid solution and transformation to the cubic phase. The resulting superplastically foamed porous ceramics having a porosity of 45% had only 40% of the thermal conductivity of the fully densified ceramics having the same composition. This value was comparable to that of conventionally fabricated porous ceramics with the same composition and porosity. The superplastically foamed ceramics had 60%, while conventionally fabricated ceramics had only 20%, of the mechanical strength of the fully dense ceramics. (c) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.msea.2013.05.084

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Ferroelectric Domain Contribution to the Tunability of Ba08Sr02TiO3 Ceramics Reviewed

Japanese Journal of Applied Physics 52 09KF06 2013.9

Ferroelectric Domain Contribution to the Tunability of Ba0.8Sr0.2TiO3Ceramics

Takashi Teranishi, Tsuyoshi Sogabe, Hidetaka Hayashi, Akira Kishimoto, Kazuhiro Fujimori

Japanese Journal of Applied Physics 52 ( 9S1 ) 09KF06 - 09KF06 2013.9

Thermoelectric efficiency of reduced SrTiO 3 ceramics modified with la and Nb Reviewed

Takashi Teranishi, Yusuke Ishikawa, Hidetaka Hayashi, Akira Kishimoto, Misaki Katayama, Yasuhiro Inada

Journal of the American Ceramic Society 96 ( 9 ) 2852 - 2856 2013.9

Language：English Publishing type：Research paper (scientific journal)

Ceramics of LaxSr1-xNbyTi 1-yO3 (LSNT) were synthesized under various reducing atmospheres. Covering the specimens with graphite carbon felt under an Ar-gas flow during sintering drastically enhanced the electrical conductivity, σ. Ti K-edge absorption spectra indicated the presence of Ti3+ for heavily reduced specimens. The increase in conductivity was attributed to the 3d band of Ti3+. The maximum value for the figure of merit, ZT, was obtained for strontium titanate ceramics modified with both 5 mol% La and 5 mol% Nb, namely 5/5-LSNT, exhibiting a ZT value of ~0.221 at 473 K. This high ZT value was almost 1.5 × larger than that of the conventional 10 mol% La-doped sample, 10/0-LSNT (ZT~0.144), and was mainly attributed to the larger Seebeck coefficient of the material. © 2013 The American Ceramic Society.

DOI： 10.1111/jace.12379

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Lithium ion conductivity of Nd-doped (Li, La)TiO3 ceramics Reviewed

Takashi Teranishi, Michihiro Yamamoto, Hidetaka Hayashi, Akira Kishimoto

SOLID STATE IONICS 243 18 - 21 2013.7

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Lithium (Li) ion conductivities of Nd-doped (Li, La)TiO3 (LLNT) ceramics are evaluated as a function of Nd-loading. The bulk ion conductivity, sigma(dc), improves for the specimen with -0.75 mol% Nd. The conductivity of the 0.5 mol% Nd-loaded LLNT is sigma(dc) = 1.26 x 10(-3) S cm(-1) at room temperature. It is the highest conductivity measured, and is 1.33 times higher than that of the non-doped ceramic. The enhancement of the Li ion conductivity with Nd-doping in the LLNTs is attributed to an increase in the volume fraction of the A-site disordered cubic phase. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ssi.2013.04.014

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Maintaining the mechanical strength of La-, Y- co-substituted zirconia porous ceramics through the superplastically foaming method Reviewed

Materials Science and Engineering: A 581 98 - 103 2013.6

Lithium ion conductivity of Nd-doped (Li, La)TiO3 ceramics Reviewed

Solid State Ionics 243 18 - 21 2013.5

Effect of millimeter-wave irradiation on cation interdiffusion in the calcium titanate/strontium titanate ceramic couple Reviewed

Materials Chemistry and Physics 139 825 - 829 2013.5

Thermoelectric Efficiency of Reduced SrTiO3 Ceramics Modified with La and Nb Reviewed

Journal of the American Ceramics Society 96 ( 9 ) 2852 - 2856 2013.5

Effect of millimeter-wave irradiation on cation interdiffusion in the calcium titanate/strontium titanate ceramic couple Reviewed

Akira Kishimoto, Yukari Kamakura, Takashi Teranishi, Hidetaka Hayashi

MATERIALS CHEMISTRY AND PHYSICS 139 ( 2-3 ) 825 - 829 2013.5

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

Interdiffusion between the perovskite CaTiO3 and SrTiO3 diffusion couple was investigated in an annealing method using 24-GHz MMW irradiation as the heating source. Interdiffusion was enhanced by MMW irradiation, and the apparent activation energy for interdiffusion decreased 54%, compared with conventional furnace heating. The intrinsic diffusions for both Ca2+ and Sr2+ were also enhanced, although their relative degrees of enhancement differed, partly as a result of differences in MMW absorptivity between the two ceramics. The observed isothermal diffusion enhancement could be ascribed to a nonthermal effect, apart from the differential degree of enhancement between the transport species. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2013.02.038

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SUPERPLASTICALLY FOAMING METHOD FOR RELIABLE POROUS CERAMICS Reviewed

Akira Kishimoto, Takahiro Nakagawa, Takashi Teranishi, Hidetaka Hayashi

SUPERPLASTICITY IN ADVANCED MATERIALS 735 109 - 112 2013

Language：English Publishing type：Research paper (international conference proceedings) Publisher：TRANS TECH PUBLICATIONS LTD

Porous ceramics incorporate pores to improve several properties including thermal insulation, maintaining inherent ceramic properties such as corrosion resistance and large mechanical strength. Conventional porous ceramics are usually fabricated through an insufficient sintering, leading to degraded strength and durability. Contrary to this, we have innovated superplastically foaming method to make ceramic foam only in the solid state. In this method, the previously inserted foam agent evaporates after the full densification of matrix at around the sintering temperature. Closed pores expand utilizing the superplastic deformation driven by the evolved gas pressure. Based on this concept we fabricated 8mol% yttria stabilized zirconia based porous ceramics and examined the properties concerning the high temperature structural material with thermal insulation.

DOI： 10.4028/www.scientific.net/MSF.735.109

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Microscopic Conduction Behavior Analysis on ZrO2-based Ion Conductors by Wideband Conductivity Measurement Reviewed

Takashi Teranishi, Kosuke Shimizu, Hidetaka Hayashi, Akira Kishimoto

ELECTROCERAMICS IN JAPAN XV 566 141 - 144 2013

Language：English Publishing type：Research paper (international conference proceedings) Publisher：TRANS TECH PUBLICATIONS LTD

All contributions to the total conductivity, electrolyte electrode interfaces, grain boundaries, ion-hopping, and optical phonons, were determined on the 8 mol% yttria-stabilized zirconia (8YSZ) and 8 mol% ytterbia-stabilized zirconia (8YbSZ) ceramics using the wideband conductivity spectroscopy. Complex conductivity spectra from 10(-1) Hz to 10(14) Hz were successfully obtained. The higher total conductivity of the 8YbSZ ceramics compared to the 8YSZ in wideband frequencies as mainly attributed to difference in the DC conductivity due to universal dielectric response (UDR), sigma(dc); sigma(dc) ((8YbSZ)) > sigma(dc) ((8YSZ)). Other parameters in the UDR and the optical phonon parameters did not greatly influence on the difference in their intrinsic conductivities.

DOI： 10.4028/www.scientific.net/KEM.566.141

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Superplastically Foaming Method for Reliable Porous Ceramics Reviewed

Materials Science Forum 735 109 - 112 2012.12

塑性発泡法によるセラミックスへの螺旋状連通閉気孔の導入 Reviewed

粉体および粉末冶金 2012.2

Thermoelectric Property of Polycrystalline Aluminum-Doped Zinc Oxide Enhanced by Micropore Foaming Reviewed

Journal of the American Ceramic Society 95 ( 2 ) 690 - 695 2012.2

Thermoelectric Property of Polycrystalline Aluminum-Doped Zinc Oxide Enhanced by Micropore Foaming Reviewed

Takashi Teranishi, Yosuke Mori, Hidetaka Hayashi, Akira Kishimoto

JOURNAL OF THE AMERICAN CERAMIC SOCIETY 95 ( 2 ) 690 - 695 2012.2

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

A unique micropore foaming technique was used to enhance the thermoelectric properties of polycrystalline aluminum-doped zinc oxide (AZO). Silicon carbide (alpha-SiC) and aluminum nitride (AlN) were used as foaming precursors. Thermoelectric conductivity, kappa, decreased on addition of both precursors, increasing the porosity. Electric conductivity, sigma, decreased upon addition of alpha-SiC, and subsequent addition of AlN reversed the effect. This phenomenon is due to the chemical reactions that occur upon addition of each precursor: the active oxidation of alpha-SiC and the decomposition reaction of AlN. The Seebeck coefficient, S, for 0.5 mol% AlN-doped AZO (Al0.005Zn0.995O, AZO-0.005) was more than twice that of conventional non-doped AZO. Accordingly, the power factor and the figure of merit, ZT, for the porous AlN-doped AZO-0.005 were 4.9 and 5.8 times those of the conventional polycrystalline AZO, respectively, demonstrating that the compositionally optimized porous AZO exhibited excellent thermoelectric properties at high temperatures.

DOI： 10.1111/j.1551-2916.2011.04837.x

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ミリ波-HIP複合焼結法で焼成したAINセラミックスに及ぼす還元雰囲気の影響 Reviewed

粉体および粉末冶金 2012.1

Quasi-millimeter-wave absorption behavior in Y/Yb-stabilized zirconia ceramics Reviewed

Applied Physics Letters 100 242903 2012.1

超塑性発泡法における窒化物系新規発泡剤の探索と特性評価 Reviewed

耐火物 2012.1

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