記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-V C H VERLAG GMBH  

The application of oxide coating on the surfaces of active cathode materials is an effective method for improving the electrochemical durability of lithium-ion batteries because it suppresses oxygen gas release from the surface of the cathode material. This report summarizes a study conducted on verifying the suppression of oxygen release from a LiCoO2 cathode material using BaTiO3 (BT), which has recently attracted attention as a new coating material. The use of first-principles calculations and machine learning as verification methods is described. In addition to the discussion of interfacial properties based on atomic- and electronic-level considerations, comprehensive verification of the interface with several junction patterns is described. The verification results suggest that the desorption of oxygen from the surface of the active material is hindered by the oxide coating, indicating the effectiveness of BT as a coating material.

DOI： 10.1002/pssb.202100526

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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：IEEE  

A terahertz (THz) chemical microscope has been developed to measure the electric potential distribution of liquid phase lithium ion batteries (LIBs) during charging and discharging. A LIB was fabricated on a sensing plate, which consists of SiO2 and Si films on a sapphire substrate, to generate THz pulses by a laser irradiation. Since the amplitude of THz is proportional to the electric potential on the sensing plate, the electric potential distribution of the lithium ion battery on the sensing plate could be visualized. In this study, the electric potential distribution across a conventional all-solid-state LIB was measured by immobilizing the LIB on the sensing plate using epoxy resin. The distribution of the electric potentials of the battery was clearly visualized by the TCM. This result indicates that the TCM could be one of useful tools for the development high performance batteries.

DOI： 10.1109/IRMMW-THz50927.2022.9896121

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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 SCI LTD  

The mechanical strength and electrical characteristics of 10 mol% gadolinium (Gd)-doped ceria (10GDC) and gadolinium-samarium (Gd-Sm) co-doped ceria ceramics treated by contact reduction were investigated. The observed increased strength of 10GDC was similar to the strength previously reported for ceria with and without Sm doping. X-ray photoelectron spectroscopy revealed that only the surface was reduced in the strengthened material. In addition, the strengthened ceramic displayed improved hardness at low test loads, which suggested the formation of a surface compression layer. The reducing conditions did not affect the electrical conductivity of the 10GDC material. Co-doping with 10 mol% each of Gd and Sm improved strength and conductivity compared with 10GDC and 20GDC. When the co-doped material was reduced, the electric conductivity remained identical; however, the mechanical strength improved, exceeding the strength of zirconia.

DOI： 10.1016/j.ceramint.2022.04.166

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

This article reports a clinical and histopathological perspective which noted not only COVID-19 pneumonia but also exacerbation of chronic renal failure potentially caused by thrombus in the kidney, possibly COVID-19-related lesions. The accumulation of autopsy cases will elucidate the pathogenesis of COVID-19 and aid in the development of effective therapeutics.

DOI： 10.1002/ccr3.6024

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AIP Publishing  

We report on the pulsed-laser-deposition (PLD) based nanodecoration of LiCoO₂ (LCO) with BaTiO₃ (BTO) nanoparticles (NPs) aimed at increasing the density of dielectric-active material–electrolyte triple-phase interfaces (TPIs). The BTO-NPs were deposited onto LCO at different numbers of laser pulses (N_Lp) and two different schemes, namely, (i) BTO-NP deposition on the surface of the precast cathode (“2D-nanodecoration”) and (ii) BTO-NP decoration of LCO powder prior to its processing to form a working cathode (“3D-nanodecoration”). While the “2D-nanodecoration” mode was found to improve significantly the discharge capacity of the LCO cathodes (by ∼30 mAh/g for N_Lp ≥ 200), their capacity retention (CR) was modest. In contrast, the “3D-nanodecoration” scheme enabled not only the volumic nanodecoration of the LCO powder by BTO-NPs but also their subsequent annealing to improve their crystallinity. These 3D-nanodecorated LCO cathodes were found to exhibit significantly higher CR values. In particular, for N_Lp = 100 k, a CR (@10 °C) as high as 78% was achieved (∼47% higher than that of their sol–gel-processed cathode counterparts). Our results point out that three key ingredients (small BTO-NP size, high D_TPI, and high dispersibility of NPs on LCO) should be combined to ensure a high CR of BTO-NP-decorated LCO cathodes.

DOI： 10.1063/5.0075970

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

The applicability of rice husks to solid phase foaming ceramics was assessed. Through an atmospheric heat treatment on silicon carbide based mixture produced by the reduction heat treatment of rice husks, the residual carbon was mostly eliminated, giving a foaming agent composed of approximately SiC and SiO2. Solid-phase foamed porous ceramics was fabricated using this rice husk-derived foaming agent and the properties were compared with that fabricated from commercially available SiC. The sample fabricated from the rice husk-derived foaming agent showed favorable performances in terms of both strength and heat insulating properties. In comparison with the sample fabricated by adding commercially available silica in addition to commercial SiC, the strength became comparable, however, its heat insulating property was still inferior to that using rice husk-derived foaming agent. The increase in mechanical strength can be ascribed to the suppression of the grain growth due to the added silica. The formed silica phase existing at the grain boundaries would affect the thermal conductivity.

DOI： 10.1007/s10934-021-01156-3

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その他リンク： https://link.springer.com/article/10.1007/s10934-021-01156-3/fulltext.html

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY  

Drastic enhancement in the high-rate capability of lithium-ion batteries to the level of supercapacitors while maintaining high energy density is required for next-generation power sources. Incorporating dielectric BaTiO3 (BTO)-based nanocubes (NCs) into the active materials-electrolyte interface provides an ultrafast charge transfer pathway via the dielectric layer. The highly dispersed NC-decorated LiCoO2 (LCO) treated at the optimized temperature of 600 degrees C displays significantly enhanced high-rate capability; the cell maintains 56.7 mAh g(-1) at 50C (1C = 160 mA g(-1)), which compares with null capacity at the same rate for bare LCO. Comparing the NCs with conventional sol-gel-derived nanoparticles, the capacity retention at 10C (vs 0.1C) steadily increases with increasing active materials-dielectric-electrolyte triple-phase interface (TPI) in the NC-decorated case, whereas the capacity retention decreases markedly at similar TPI density in the sol-gel case. In the sol-gel case, the amount of Li ions accumulating at the TPI greatly exceeds the maximum amount of Li ions involved in electron exchange through the redox reaction within the charge/discharge time. In the NC case, most Li ions at the TPI participate effectively in the redox reaction, which results in fast charge transfer since the TPI sites are abundantly supplied with Li ions.

DOI： 10.1002/admi.202101682

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

In recent years, with the spread of electric vehicles, improvement in the performance of lithium ion batteries has been required. Evaluation of the active material is important because the performance of the lithium ion battery is affected by the movement of lithium ions at the electrode active material-electrolyte interface. In this study, we fabricated a lithium ion battery with the sensing plate, which is a potential sensor, attached to the positive electrode, and evaluated lithium ion battery with a terahertz chemical microscope (TCM). As a result, we succeeded in measuring the potential distribution of the positive electrode during charging and discharging, and the local impedance.

DOI： 10.1002/eej.23355

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/eej.23355

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

High-speed rechargeability is essential for next-generation secondary batteries. Introducing a surface-supporting material deposited on a cathode material accelerates Li-ion motions between an electrode-electrolyte interface by an electric field concentration at a supporting material-cathode-electrolyte (triple-phase) interface (TPI). In addition, a high relative permittivity material was found to be a promising supporting material with which to reinforce the electric field concentration at TPIs. However, the TPI's effects on anode materials remains to be revealed. To demonstrate those effects, we prepared CeO2 or BaTiO3 micropads deposited on Li4Ti5O12 epitaxial thin films. Compared with the cathodes, CeO2 micropads deposited on Li4Ti5O12 film showed the best performance at a high C-rate. Because the rate-determining step of Li4Ti5O12 epitaxial thin films is inner diffusion, reinforcing the surface electric field by the deposition of a low relative permittivity materials could promote high C-rate performance even in anode materials.

DOI： 10.35848/1347-4065/ac15a8

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

Recently, we reported linear electro-optic (EO) effects in (100)-epitaxial yttrium-doped hafnium dioxide (Y-HfO2) ferroelectric thin films. In this study, we have investigated the influence of orientation on the EO effect in Y-HfO2 thin-film. (111)-epitaxial undoped HfO2 and Y-HfO2 films were deposited on Sn-doped In2O3/yttria-stabilized zirconia (111) substrates at room temperature through radiofrequency magnetron sputtering. Although the undoped HfO2 film showed typical paraelectric characteristics, ferroelectricity was observed in the (111)-Y-HfO2 film. Remnant polarization in the (111)-Y-HfO2 film was higher than that in the (100)-Y-HfO2 film. The (111)-Y-HfO2 film exhibited a linear EO effect based on ferroelectricity, which is consistent with that of the (100)-Y-HfO2 film. The average EO coefficient r (c) of the (111)-Y-HfO2 film was 0.67 pm V-1, which is higher than that of the (100)-Y-HfO2 film. This result is reasonable considering the difference in remnant polarization between the (100)-Y-HfO2 and (111)-Y-HfO2 films.

DOI： 10.35848/1347-4065/ac17e0

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その他リンク： https://iopscience.iop.org/article/10.35848/1347-4065/ac17e0/pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AIP Publishing  

We deposited polar-axis-oriented tetragonal and rhombohedral single domain Pb(Zr, Ti)O-3 (PZT) films on CaF2(100) substrates by inserting SrRuO3 (SRO)/LaNiO3 and SRO/SrTiO3/TiO2/CeO2 buffer layers. Both PZT films grew epitaxially and had a (001)- and (111)-domain with the remnant polarization and piezoelectric constant comparable to the theoretical values of PZT single crystals having the same compositions. The electro-optic (EO) response of the fabricated PZT films was constant with respect to the DC electric field and increased linearly with an increasing AC electric field, thus representing a typical linear EO response in single domain ferroelectrics. The measured EO coefficients were larger than the value for a single crystal of PbTiO3, i.e., one of the end members of PZT, but smaller than the values reported for polycrystalline and epitaxial PZT films with multiple domains. These findings show that the intrinsic EO effect is enhanced in PZT, which is similar to the enhancement seen in the dielectric and piezoelectric constants. Moreover, most of the reported EO response in PZT films is supported by additional extrinsic contributions.

DOI： 10.1063/5.0056121

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

<title>Abstract</title>
Electro-optic (EO) modulators for silicon photonics using CMOS-compatible materials and processes are in great demand. In this study, epitaxial (100)-undoped HfO₂ and Y-doped HfO₂ thin films were fabricated on Sn-doped In₂O₃/yttria-stabilized zirconia(100) substrates at room temperature via magnetron sputtering. EO measurement of the Y-HfO₂ film using modulation ellipsometry showed that the phase was changed by 180° after application of positive and negative poling biases, and the modulation amplitude increased linearly with increasing AC electric field, indicating a linear EO effect based on ferroelectricity. The observed results indicate that ferroelectric HfO₂-based films are viable candidates for CMOS-compatible EO devices.

DOI： 10.35848/1347-4065/ac087d

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その他リンク： https://iopscience.iop.org/article/10.35848/1347-4065/ac087d/pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Side reactions of the charge/discharge in Li-ion batteries (LIBs) generate a solid-electrolyte interface (SEI) onto an electrode surface, resulting in the degradation of the lifetime of a cell. The suppression of SEI formations has attracted much attention for achieving longer cyclable LIBs. Our research group has previously reported that few SEI were observed at triple-phase interfaces (TPIs) consisting of BaTiO3, LiCoO2, and electrolyte interfaces in LIBs with excellent cyclability and ultrahigh-speed chargeability. An investigation on the suppression mechanisms of SEI formations at TPIs should yield important information on understanding the undesirable side reactions. Therefore, we have explored the suppression mechanisms of SEI formations by preparing epitaxial thin films and evaluating the surface of the samples after the electrochemical treatment. The results of X-ray photoelectron spectroscopy and scanning electron microscopy with energy-dispersive X-ray analysis measurements suggested that the decomposition of LiPF6 was suppressed at TPIs, implying that the generation of PF5 via the decomposition of LiPF6 contributed to SEI formation.

DOI： 10.1021/acsami.1c05090

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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  

High-speed rechargeable Li ion batteries are in strong demand. Two methods have been reported to improve the high-speed rechargeability of electrodes: reducing particle size and introducing a surface support. However, the effectiveness of the latter could not be directly compared among reports due particle size differences from study to study. Our previous report revealed that Li+ motion under high-speed charge-discharge conditions is accelerated around a surface-supporting material, an electrode, and an electrolyte interface. In this study, we prepared epitaxial LiCoO2 thin films with micropads of various kinds of materials and evaluated the high-speed rechargeability of each. (C) 2021 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.20237

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担当区分：筆頭著者,　責任著者   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  

We report ultrafast charge transfer along the Li-ion pathway via a dielectric layer at the electrolyte electrode interface. The rate capabilities of dielectric-modified cathodes were evaluated as a function of the combination of electrolyte solvents and dielectric layers having various dielectric constants, epsilon(r). The high-rate capability was enhanced when the loaded dielectric layer's epsilon(r) was close to that of the electrolyte solvent. Density functional theory molecular dynamics calculations and atomic force microscope force measurements confirmed that the activation energies related to Li+ adsorption and desolvation were notably reduced when the loaded dielectric layer's epsilon(r) approached that of the solvent. In this case, the solvated Li+ ion preferentially underwent desolvation on the solid surface. The discharge capacity at the ultrahigh rate of 50 C (1 C = 160 mA g(-1)) of the dielectric-modified thin films steadily increased with increasing length of the dielectrics electrode electrolyte triple-phase interface (TPI). Experimental and computational results reveal that, when the permittivity of the dielectrics and solvent are similar, solvated Li+ ions are preferentially involved in the physical adsorption and desolvation on the dielectric surface, followed by Li+ intercalation near the TPI.

DOI： 10.1016/j.jpowsour.2021.229710

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

A novel colossal polarization architecture generated at the fast Li-ion conductor-dielectric interface is proposed. A fast Li-ion conductor, La0.57Li0.29TiO3 (LLT), is utilized as the conductive core material, while the ferroelectric barium titanate (BaTiO3; BT) was coated onto the LLT as the shell layer via a liquid phase reaction. After densification of the composites, the shell BT fully transforms into the interdiffusion layer, i.e. (Ba, Li, La)TiO3 (BLLT). The BLLT effectively hinders Li diffusion, leading to a colossal polarization at the core-shell interface. Consequently, the optimized BT-LLT achieves dielectric characteristics at 1 kHz with permittivity of 3.28 x 10(4).

DOI： 10.35848/1347-4065/abf088

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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：IEEE  

In recent years, all-solid-state batteries have been attracting attention as secondary batteries to replace Li ion batteries. To improve the performance of all-solid-state batteries, measurement methods are required to evaluate electrode-solid electrolyte interfaces and electrochemical reactions between electrodes. In this study, we investigated a measurement method for the cross-section of all-solid-state batteries using terahertz chemical microscopy (TCM). We fabricated a model of all-solid-state battery and showed the possibility of using TCM to measure the cross-section of the all-solid-state battery by measuring the cross-section of a model of all-solid-state battery.

DOI： 10.1109/IRMMW-THz50926.2021.9567015

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

A terahertz chemical microscope has been developed to visualize electric potential distribution on lithium ion battery cathodes during battery operation. A sensing plate comprising a Si film grown epitaxially on a sapphire substrate was used as a terahertz emitter. The amplitude of terahertz radiation from the sensing plate could be related to the electric potential at the exact point where a femtosecond laser illuminated. Here, the sensing plate was integrated into a conventional can-type lithium ion battery and terahertz radiation from the sensing plate was observed during battery operation between 2.7 and 4.2 V. By scanning the laser, the distribution of terahertz amplitude radiated from the sensing plate was observed, which could be related to the electric potential distribution on the electrodes of the batteries. Localized electric potential could be visualized as the amplitude of terahertz radiation generated in the sensing plate, which was integrated beneath the battery electrode.

DOI： 10.1007/s10762-019-00640-x

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society of Powder and Powder Metallurgy  

DOI： 10.2497/jjspm.67.163

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掲載種別：研究論文（学術雑誌）   出版者・発行元：AIP Publishing  

DOI： 10.1063/1.5087061

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掲載種別：研究論文（学術雑誌）   出版者・発行元：American Chemical Society (ACS)  

DOI： 10.1021/acs.nanolett.8b04690

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Japan Society of Powder and Powder Metallurgy  

DOI： 10.2497/jjspm.65.475

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/jace.15242

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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 BV  

High operation temperature of solid oxide fuel cell (SOFC) results in high cell and operation cost, time consuming and fast cell degradation. Developing high performance SOFC that operates at lower temperature is required. Here we demonstrate 24 GHz microwave as a rapid heating source to replace conventional heating method for SOFC operation using 20 mol% Sm doped CeO2 electrolyte-supported single cell. The tested cell shows improvement of 62% in maximum power density at 630 °C under microwave heating. This improvement governs by bulk conductivity of the electrolyte. Investigation of ionic transference number reveals that the value is unchanged under microwave irradiation, confirming the charge carrier is dominated by oxygen ion species. This work shows a potential new concept of high performance as well as cost and energy effective SOFC.

DOI： 10.1016/j.jpowsour.2017.11.036

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2497/jjspm.65.21

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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：IEEE  

We measured the terahertz wave intensity of the active material surface using TCM as a method to evaluate lithium ion batteries. We made a battery with a sensing plate attached to measure with TCM. As a result, changes in the terahertz wave intensity due to charging and discharging of the battery could be measured. This result indicates that the extraction and insertion of lithium in the active material can be measured by TCM in the future.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本セラミックス協会  

Improving the conductivity of 8 mol % yttria-stabilized zirconia (8YSZ) electrolyte has enabled a lowering of the operating temperature of solid oxide fuel cells. We previously reported that millimeter-wave irradiation heating increases the ionic conductivity of ceramics. The ionic conductivity of 8YSZ under millimeter-wave irradiation heating had been up to 20 times higher than that with conventional heating. In the present study, we investigated the optimal thermal environment for millimeter-wave irradiation heating. We also investigated the thermal profile of samples under millimeter-wave irradiation heating to elucidate the rate of the non-thermal effect.

DOI： 10.2109/jcersj2.17056

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Institute of Physics  

Cyclic characteristics of BaTiO<inf>3</inf>(BT)-decorated LiCoO<inf>2</inf>(LC), for use as an artificial solid electrolyte interface (SEI) were evaluated at high voltages. Within the standard voltage window (i.e., 3.3–4.2 V), the BT-decorated LC exhibited greater capacities for up to 80 cycles compared with both the Al<inf>2</inf>O<inf>3</inf>(paraelectric)-decorated and bare LC SEIs. The discharge capacity retention after 80 cycles (compared with the initial value) was 86.0% for the BT–LC cathode. This is a significant improvement over both the bare LC that showed 19.9% retention and the Al<inf>2</inf>O<inf>3</inf>–LC that displayed 71.5% retention. Thereafter, the cyclic stabilities of the BT–LC and bare LC were compared within potential windows at cutoff voltages as high as 4.9 V. In this region, BT decoration yielded marked improvements in capacity retention after 50 cycles, up to a potential of 4.7 V. The post-situ XRD analysis of the cathode sheets showed that BT decoration effectively stabilized the hexagonal crystal structure of the LC, H1, resulting in the said cyclic stability increase. These observations demonstrate that the use of BT in SEI allows a significant increase in working voltage while maintaining the chemical stability of the underlying LC matrix, a key advancement in the perpetual pursuit of ever higher cell energy densities.

DOI： 10.7567/JJAP.56.10PC01

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2109/jcersj2.17083

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掲載種別：研究論文（学術雑誌）   出版者・発行元：The Surface Finishing Society of Japan  

DOI： 10.4139/sfj.68.401

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/jace.14768

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/jace.14700

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.matdes.2016.11.051

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：粉体粉末冶金協会  

CiNii Article

CiNii Books

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/1.4964803

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1063/1.4964803

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.7567/JJAP.55.10TB01

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Japan Society of Powder and Powder Metallurgy  

The preparation of a stable suspension dispersing carbon nanotube (CNT) in aqueous media using polystyrene maleic acid (PSMA)-based polymer as surfactant was attempted to be subsequently used in the fabrication of high-performance ceramic matrix composites. Settling velocity under centrifugation analysis was experimentally evaluated as one of the stability criteria of the dispersion and pulsed nuclear magnetic resonance was used to evaluate the amount of adsorbed molecules. The settling velocity decreased considerably with the PSMA concentration up to the saturation at around 7 mass%, then further decreased gradually with PSMA. The former was thought to be based on the dissociation of CNT agglomerate and the latter would be attributed to the surfactant-induced network structure formed in the aqueous media.

DOI： 10.2497/jjspm.63.861

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記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Wiley Blackwell  

Our innovative superplastically foaming method was used to create closed-pore inclusive zirconia-based ceramics. Yttrium oxide was added to monoclinic zirconia to stabilize the matrix. Sintering and superplastic deformation were used to form a solid solution and transform it to a cubic phase. Porous ceramics formed via this post-stabilization method exhibited anomalous thermal expansion due to the silica derived from the foaming agent SiC. This anomalous thermal expansion disappeared following substitution of the SiC foaming agent for AlN. The resulting superplastically foamed porous ceramics exhibited large thermal conductivities, comparable to that of the fully densified ceramics, but with a porosity as great as 35%. This high thermal conductivity was attributed to the alumina derived from the foaming agent AlN. To suppress the formation of alumina, the samples were pre-sintered in an argon atmosphere. The modified superplastically foamed ceramics exhibited smaller pores, with a porosity of 33%, as well as favorable thermal insulation, with a thermal conductivity that was approximately half that of the fully dense material.

DOI： 10.1002/9781119234463.ch7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 粉体粉末冶金協会  

<p>Sm-doped CeO₂ ceramics were prepared by conventional solid state method. The electrical conductivity of the samples was measured under conventional heating and 24 GHz millimeter-wave (MMW) heating, and the results were compared. During MMW heating, 5 mol% Sm-doped CeO₂ pellets with different thickness were used as susceptors, meanwhile Al₂O₃ fiber board was used as thermal insulator and its design varies by the number of open channels. The aforementioned susceptors and thermal insulators dependency of conductivity values during MMW heating were studied. Conductivity of samples under MMW heating was found to be higher than under conventional heating. Results showed that the different susceptor thickness and thermal insulator design could result in different conductivity values. These results were attributed to the phenomenon of heat dissipation from surface and the amount of direct radiation reached the sample. Specific susceptor thickness and specific insulator design which leads to highest conductivity were identified. By combining these two effects, the largest enhancement of conductivity of ceria based ceramics was obtained.</p>

DOI： 10.2497/jjspm.63.663

CiNii Article

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ssi.2015.11.029

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2497/jjspm.63.981

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2109/jcersj2.16009

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

DOI： 10.11316/jpsgaiyo.71.1.0_2691

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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 SA  

Ionic conductivity was measured on scandia-, calcia-, and gadolinia-stabilised zirconia ceramics under quasi-millimeter-wave (MMW) irradiation heating and conventional heating. Conductivity enhancement was evaluated for these ceramics and compared with our previous report on yttria- and ytterbia-stabilised zirconia ceramics (YSZ and YbSZ, respectively). The ionic conduction for the various cation-substituted zirconia ceramics was enhanced under MMW irradiation heating. In the case of scandia-stabilisation, the optimal composition demonstrating maximum ionic conductivity was 12-mol% zirconia (ScSZ) under MMW irradiation heating, which was larger than under conventional heating. Such an optimal composition shift was similar to results for YSZ ceramics. These results are discussed in terms of the activation energies for vacancy-ion dissociation and ion transfer. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2015.07.057

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

In situ electrochemical impedance spectroscopy (EIS) was undertaken to investigate the contribution of a ferroelectric artificial solid electrolyte interface (SEI) to the enhancement of the rate capability of lithium ion batteries. Resistance elements, consisting of the cell reactions, the resistance of the electrolyte, R-sol, that of the Li metal anode reaction, R-Li, and the charge transfer resistance, R-ct, were measured. A small ferroelectric BaTiO3 (BT) load, similar to 1 mol %, notably reduced R-ct and R-sol compared with bare LiCoO2 (LC), indicating that loaded ferroelectric BT SEIs effectively promote Li inter/deintercalation into and from the active material, LC, and restrict cobalt ion dissolution into the electrolyte liquid. Lower R-ct and R-sol resulted in a significantly higher capacity retention ratio at a 10C rate compared with the initial cycle for small BT load, similar to 1 mol %. The capacity retention dropped rapidly, accompanied by a slight increase in R-ct for larger BT loads, 5 and 15 mol %, which may be attributed to the thicker BT layer and the existence of the impurity phase, BaCO3. These results imply that the ferroelectric SEI affected the kinetics of mobile Li ions at the cathode-electrolyte interface, significantly enhancing the rate capability. (C) 2015 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.54.10NB02

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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 SCI LTD  

The effect of quasi-millimetre-wave (24 GHz microwave) heating on creep deformation was investigated on partially-stabilised zirconia through tensile testing at temperatures from 1100 to 1350 degrees C over stresses from 5 to 10 MPa. The specimens were fabricated by sintering the 3 mol% of yttria stabilised ZrO2 (3YSZ) powder dispersed with SiO2, SiO2/SnO2 or SiO2/TiO2 at 1600 degrees C. In tensile test using the quasi-millimetre wave heating, strain rates of SiO2 dispersed 3YSZ were similar to that with a conventional furnace heating. The 3YSZ sample containing the TiO2 addition exhibited a different strain rate when heated by millimeter-wave irradiation as against conventional furnace heating, it is proposed that this difference can be explained due to TiO2 having a high-dielectric constant resulting in a non-thermal effect when subjected to quasi-millimeter wavelength radiation. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

DOI： 10.1016/j.ceramint.2015.01.006

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELECTROCHEMICAL SOC INC  

Ferroelectric barium titanate, BaTiO3 (BT) was coated on lithium cobaltate, LiCoO2 (LC), as an artificial solid electrolyte interface (SEI), via the simple sol-gel route. The high charge-discharge rate capabilities of the composite cathodes were evaluated up to 10C. The LC loaded with 1 mol% of BT had a measured capacity of 146 mAh/g, which was the highest value measured at 10C. This capacity was 78% of its initial value, and was 238% of the capacity of bare LC over the same number of cycles. (C) 2015 The Electrochemical Society. All rights reserved.

DOI： 10.1149/2.0041512eel

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

DOI： 10.11316/jpsgaiyo.70.1.0_2743

CiNii Article

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

DOI： 10.11316/jpsgaiyo.70.1.0_2704

CiNii Article

CiNii Books

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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  

The dependence of lithium ion conductivity on barium loading was investigated for Li0.33BaxLa0.56-2/3xTiO3 (LBLT, 0 &lt;= x &lt;= 0.1) ceramics. The highest bulk conductivity, sigma(dc), of 1.24 x 10(-3) S cm(-1) obtained for 0.25 mol.% Ba loading was slightly improved compared to that of non-doped Li0.33La0.56TiO3 (1.18 x 10(-3) S cm(-1)). The intensities of the XRD patterns in the independent cubic and tetragonal reflections, i.e., I-c(100) and I-t(101), were analyzed; a larger I-c(100)/I-t(101) ratio corresponded to a larger sigma(dc). A possible reason for the only slight enhancement of the sigma(dc) by a small loading of Ba is an increased volume fraction of the more highly conductive LBLT cubic phase. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ssi.2014.05.001

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

The high charge-discharge rate characteristics of composite cathodes consisting of ferroelectric BaTiO3 (BT)-coated LiCoO2 (LC), synthesized via a simple sol-gel route, were evaluated, and the rate showed stepwise increases to as high as 5C. The LC-BT composite cathode annealed at 600 degrees C, LC-BT-600, notably retained high capacities, i.e., 122 mAh/g at 30 cycles, 5C and 99 mAh/g at 60 cycles, 5C. These capacities corresponded to 83% and 67% of the initial values and were as high as 158% and 245% of the capacities of bare LC over the same cycles, respectively. The ferroelectricity of the coated BT contributed to the improvement in high-rate performance. (c) 2014 AIP Publishing LLC.

DOI： 10.1063/1.4898006

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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 SA  

Under 24-GHz millimetre-wave irradiation heating ionic conductivity of zirconia base ceramics was up to 20 times higher than that of a conventionally-heated sample at the same temperature of 400 degrees C. The degree of enhancement could be altered by changing the stabilising atom from Y to Yb. Enhancement of ionic conduction was prominent in the setup condition of larger self-heating ratio and larger MMW absorbing materials. The isothermal improvement of ionic conductivity under MMW irradiation would be ascribed to the non-thermal effect. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2013.10.002

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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  

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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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 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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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP Publishing  

DOI： 10.7567/jjap.52.09kf06

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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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  

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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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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 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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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  

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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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  

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)) &gt; 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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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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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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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)) &gt; 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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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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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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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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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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DOI： 10.1143/JJAP.49.041506

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記述言語：英語   出版者・発行元：AMER INST PHYSICS  

Ultrawideband dielectric spectroscopy analysis of barium zirconate titanate (BaZrxTi1-xO3, BZT) ceramics at different temperatures disclosed the contribution of both the dipole and the ionic polarizations to permittivity at around dielectric maximum temperature (T-m). In BaZr0.25Ti0.75O3 ceramics, the permittivity around Tm is dominated by the temperature dependence of the permittivity determined by the dipole polarization (epsilon(dipole)). In relaxor ferroelectrics, the diffuse dielectric response around Tm could be derived from the temperature dependence of epsilon(dipole). The variation of epsilon(dipole) with temperature could be also explained by the growth process of polar nanoregions (PNRs) and the damping process of the thermal fluctuation of dipoles in PNRs. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3131624]

DOI： 10.1063/1.3131624

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記述言語：英語   出版者・発行元：Elsevier BV  

Wide band dielectric spectra from the kilohertz to terahertz range were discussed for SrTiO(3) (ST) and BaTiO(3)-based ceramics. The dielectric permittivity of BaTiO(3) (BT) is determined by the ionic polarization of the Slater mode as well as the dipole polarization of domain-wall vibrations in micro-sized domains. (Ba(x),Sr(1-x))TiO(3) (BST) shows relatively high dielectric permittivity with a low dielectric loss up to GHz region, while Ba(Zr(x)Ti(1-x))O(3) (BZT) shows a high permittivity with dielectric relaxation at MHz range. The dielectric dispersion in the BZT was due to the dipole fluctuation in polar nano-regions (PNR) in relaxors. The change of dielectric spectrum from BT to BZT was interpreted by the change from normal ferroelectrics to relaxors via ferroelectrics with diffuse phase transition (DPT-ferro.). Wide band dielectric spectra were also measured for BT ceramics with different grain and domain sizes to elucidate the size effect observed in BT ceramics. The low-frequency permittivity increased with decreasing grain size when the grain size was above 1 mu m. It was found that the dipole polarization due to the domain-wall motion was enhanced with increasing domain density. We demonstrated wide band dielectric spectroscopy is a powerful tool to investigate the polarization mechanism of dielectric and ferroelectric materials. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.mseb.2008.11.039

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記述言語：英語   出版者・発行元：AMER INST PHYSICS  

Ultrawide band dielectric spectroscopy analysis of barium strontium titanate [BaxSr1-xTiO3 (BST)] ceramics at different temperatures disclosed a contribution of the dipole and the ionic polarizations to their diffuse phase transition (DPT). In the BST ceramics, thermal behavior of the ionic polarization governs the DPT. The dielectric maximum temperature (T-m) is in agreement with the maximum temperature of the permittivity determined by the ionic polarization. The maximum of the permittivity determined by the ionic polarization at the T-m is caused from the decrement of the vibration frequency of the soft mode. The dipole polarization gives small contribution to the DPT. The gradual increase in the permittivity determined by the dipole polarization with decreasing temperature could be explained by the increase in the size of the polar nanoregions.

DOI： 10.1063/1.3089250

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出願人：トヨタ自動車株式会社

出願番号：特願2019-106059  出願日：2019年6月6日

公開番号：特開2020-202022  公開日：2020年12月17日

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出願人：トヨタ自動車株式会社

出願番号：特願2019-106058  出願日：2019年6月6日

公開番号：特開2020-202021  公開日：2020年12月17日

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出願人：トヨタ自動車株式会社

出願番号：特願2019-106060  出願日：2019年6月6日

公開番号：特開2020-202023  公開日：2020年12月17日

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出願人：トヨタ自動車株式会社

出願番号：特願2018-200563  出願日：2018年10月25日

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出願人：サムソン エレクトロ-メカニックス カンパニーリミテッド.

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出願人：国立大学法人 岡山大学

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出願人：トヨタ自動車株式会社

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出願人：トヨタ自動車株式会社

出願番号：特願2017-237311  出願日：2017年12月12日

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出願人：トヨタ自動車株式会社

出願番号：特願2017-237310  出願日：2017年12月12日

公開番号：特開2019-106276  公開日：2019年6月27日

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出願人：国立大学法人 岡山大学

出願番号：特願2017-123010  出願日：2017年6月23日

公開番号：特開2019-009252  公開日：2019年1月17日

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出願人：トヨタ自動車株式会社

出願番号：特願2017-079861  出願日：2017年4月13日

公開番号：特開2018-181614  公開日：2018年11月15日

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出願人：国立大学法人 岡山大学

出願番号：特願2015-025824  出願日：2015年2月12日

公開番号：特開2016-149270  公開日：2016年8月18日

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出願人：国立大学法人 岡山大学

出願番号：特願2015-025824  出願日：2015年2月12日

公開番号：特開2016-149270  公開日：2016年8月18日

特許番号/登録番号：特許第6551878号  登録日：2019年7月12日 

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