記述言語：英語   出版者・発行元：The Ceramic Society of Japan  

DOI： 10.2109/jcersj2.25171

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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：ACS Applied Energy Materials  

The development of high-rate capability lithium-ion batteries (LIBs) requires suppression of charge-transfer resistance (R<inf>CT</inf>) at electrode–electrolyte interfaces. Here, zirconia-based dielectric oxides (MZ; M = Y, Gd, Sm, Er, etc.) were introduced onto LiCoO<inf>2</inf> (LCO) surfaces as electronically and ionically insulating modifiers to accelerate interfacial ion transport. Electrochemical impedance spectroscopy showed that Y<inf>2</inf>O<inf>3</inf> modified ZrO<inf>2</inf> (YZ) decoration reduced R<inf>CT</inf> from 75.8 Ω in reference LCO to 38.3 Ω, accompanied by a 2.3-fold improvement in capacity retention at 20C. Density functional theory molecular dynamics (DFT–MD) simulations showed that solvated Li ions coordinate with surface oxygen atoms in discharging, and that adsorption energies are governed by local charge distributions determined by stabilizing cations. Optimal adsorption activity, and thus the lowest R<inf>CT</inf>, occurred when the surface charge corrugation was balanced. These findings provide design principles for dielectric interface engineering to enhance rate capability of LIBs.

DOI： 10.1021/acsaem.5c02963

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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：Journal of the American Ceramic Society  

Multilayered ceramic capacitors (MLCCs) are demanded for miniaturized and large capacities with good reliability. To produce devices with desired properties, TiO<inf>2</inf>-based powder was co-doped with 1 % Nb and 2.5 % Mg to achieve a giant dielectric permittivity while maintaining the same particle size. A 1 % Nb-doped specimen heat-treated at 1000°C for 4 h in a reducing atmosphere with log pO<inf>2</inf> = −17.7 and without Mg doping exhibited typical insulating behavior with low interfacial polarization. Mg doping remarkably increased the dielectric constant of the resulting material to approximately 10⁴; however, it also increased its dielectric loss. The observed variations in the dielectric characteristics of the co-doped TiO<inf>2</inf> powder with the Mg doping amount were attributed to changes in the density and mobility of electrons accompanying the changes in the Mg loading concentration within a single particle. The obtained material can potentially serve as the core material of a core–shell structure for MLCCs.

DOI： 10.1111/jace.70447

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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  

DOI： 10.1016/j.mseb.2025.118499

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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：Japanese Journal of Applied Physics Part 1 Regular Papers and Short Notes and Review Papers  

By optimizing the deposition conditions and employing an AlN seed layer, Sc-doped AlN thin films with Sc concentrations of up to 26% were successfully fabricated on Pt/Al<inf>2</inf>O<inf>3</inf>(0001) using combinatorial pulsed laser deposition (PLD). It was found that the critical parameters for obtaining highly crystalline AlN films are moderate growth temperatures and an appropriate background N<inf>2</inf> partial pressure. However, it was difficult to achieve crystal growth of Sc-doped AlN on Pt/Al<inf>2</inf>O<inf>3</inf>(0001) by optimizing the growth conditions alone. It was found that the insertion of an approximately 5 nm thick AlN seed layer effectively promoted the crystallization of Sc-doped AlN films. The resulting PLD-grown Sc-doped AlN films exhibited high crystallinity and lattice parameters comparable to those of the reported films deposited by sputtering.

DOI： 10.35848/1347-4065/ae0485

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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：Japanese Journal of Applied Physics Part 1 Regular Papers and Short Notes and Review Papers  

The polarity of aluminum scandium nitride (Al<inf>1−x</inf>Sc<inf>x</inf>N) thin films with different Sc contents deposited on transparent indium tin oxide (ITO) electrode-covered yttria-stabilized zirconia (YSZ) (111) substrates using radio frequency-magnetron sputtering was investigated. The Al<inf>1−x</inf>Sc<inf>x</inf>N (x = 0), i.e. pure AlN, film on ITO/YSZ(111) exhibited Al polar. By comparing with the polarity of AlN films deposited on different substrates, including Al<inf>2</inf>O<inf>3</inf>(0001), Pt/YSZ(111), YSZ(111), Pt(111)/TiO<inf>y</inf>/SiO<inf>2</inf>/Si(100) and Si(100), it was found that the polarity is affected by the degree of epitaxy. In addition, for the Al<inf>1−x</inf>Sc<inf>x</inf>N films on ITO/YSZ(111), the transition from Al polar to N polar occurred with increasing Sc content, x, whereas the degree of epitaxy almost unchanged. These findings offer important insights into the mechanisms governing the self-poling in Al<inf>1−x</inf>Sc<inf>x</inf>N thin films and pave the way for their use in electro-optic devices.

DOI： 10.35848/1347-4065/adf7b2

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その他リンク： https://iopscience.iop.org/article/10.35848/1347-4065/adf7b2/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：The Electrochemical Society  

One of important properties for Lithium-ion batteries is well known to be the rate performance because of the need to shorten discharging time and keep sufficient performance even under high load. The rate performance means the rate of decrease in charge-discharge capacity with increasing charge-discharge rate, which resulted from the internal resistance of batteries. Therefore, decreasing the internal resistance gives the improvement of the rate performance. The authors have thought to reduce the interfacial resistance between the electrolyte and cathode because it has been thought to be the largest of internal resistances. In order to reduce the interfacial resistance, we focused on an additive material adsorbing solvated Li-ions by the electrostatic force for cathode. Based on the possibility to design the positively and negatively polarized sites and their distance, fluorite-structured (Zr,M)O_2-xwas selected for the cathode additive. The fluorite-structured (Zr,M)O_2-x substituted with trivalent cation of M was synthesized for expecting the formation of negatively and positively polarized sites that adsorb solvated Li-ions and promote the dissolvation. It is thought that M³⁺ sites are negative as base sites δ^- and oxygen vacancy Vo sites are positive as acid sites δ⁺in (Zr⁴⁺ _1-2xM³⁺ _2x)O_2-xVo_x. Temperature-programmed desorption using acidic gas CO₂ and basic gas NH₃ revealed that many strong acidic and basic sites were formed, as compared with these of ZrO₂ without M-substitution. Furthermore, the synthesized (Zr,M)_O2-x powder was dispersed at 1 mass% on cathode particles of LMO, resulting in higher discharged capacity than those of LCO without additive and with ZrO₂ especially at high rates. Thus, we demonstrated that the design of negatively and positively polarized sites and their distance in the cathode additive (Zr,M)O_2-x was effective for improving the rate performance.



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DOI： 10.1149/ma2025-013216mtgabs

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その他リンク： https://iopscience.iop.org/article/10.1149/MA2025-013216mtgabs/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：The Electrochemical Society  

The rate performance of Li-ion batteries is one of the important properties, especially for electric vehicles and power tools. The rate performance is governed by the internal resistance of a battery, which is mainly divided to electrode-resistance, electrolyte-resistance, and interfacial-resistance between electrolyte and electrode. Reducing these resistances can keep high charge-discharge capacity even at increasing charge-discharge rate, meaning the improvement of the rate performance. Among the resistances, the authors have tried to reduce the interfacial-resistance between electrolyte and cathode by using the cathode additive (Zr,M)O_2-x. The fluorite-structure of (Zr,M)O_2-xis one of candidates suitable for designing positively and negatively polarized sites that adsorb solvated Li-ions by the electrostatic force. The fluorite-structured (Zr,M)O_2-x substituted with trivalent cation of M was found to be effective in increasing the number and strength of positively and negatively polarized sites (acidic and basic sites), thereby improving the rate performance as a cathode additive. Assuming that M³⁺ sites are negative as base sites δ- and oxygen vacancy Vo sites are positive as acid sites δ⁺in (Zr⁴⁺ _1-2xM³⁺ _2x)O_2-xVo_x, it is thought that the kind of M³⁺ would affect the number and strength of negatively and positively polarized sites. Thus, we have investigated the effect of trivalent M³⁺ in cathode additive (Zr,M)O2_-x on rate performance of lithium batteries. Samples of (Zr⁴⁺ _1-2xM³⁺ _2x)O_2-xVo_x, where M=Sc, Y, La, Nd, Sm, Gd, Ho, Er, Yb, etc. and x=0.15, were prepared by a wet method. The experimental results of temperature-programmed desorption using acidic gas CO₂ and basic gas NH₃ revealed that the number and strength of acidic and basic sites corresponding to positively and negatively polarized sites, respectively, varied depending on M³⁺. Each (Zr,M)O_2-x powder was also dispersed at 1 mass% on cathode particles of LMO, showing the improvement of discharged capacity at high rates depending on M³⁺. The discharged capacity at high rates was found to have a tendency to become higher with increasing the number and strength of acidic and basic sites. This may result from differences in features of M such as ionic size, configuration of M³⁺ and Vo, electronegativity of M, and ligand-field stabilization energy of M³⁺.

DOI： 10.1149/ma2025-013382mtgabs

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その他リンク： https://iopscience.iop.org/article/10.1149/MA2025-013382mtgabs/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：Applied Physics Letters  

We investigated the dependence of the electro-optic (EO) properties of (111)-epitaxial Hf<inf>0.5</inf>Zr<inf>0.5</inf>O<inf>2</inf> (HZO) thin films on their thickness in the range of 3-30 nm. HZO films were deposited on (La, Sr)MnO<inf>3</inf>-bufferred SrTiO<inf>3</inf>(001) substrates using pulsed laser deposition. Both the ferroelectric orthorhombic and paraelectric monoclinic phases were found to coexist in the 30 nm thick film, and the fraction of the former phase increased with the decrease in thickness down to 5 nm. Although the effective EO coefficient, r<inf>eff</inf>, remained almost unchanged down to 10 nm and decreased with a further decrease in thickness, the evident EO response was observed down to 3 nm, which agrees with the fact that HZO films can maintain ferroelectric properties down to a few monolayers in thickness. The small r<inf>eff</inf> in the HZO films with thickness below 5 nm was attributed to the stabilization of the ferroelectric rhombohedral-like phase.

DOI： 10.1063/5.0267559

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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：AIP Publishing  

The electrocaloric effect (ECE)-induced temperature change (ΔT) in (Ba, Sr)TiO3-based ferroelectrics under unipolar electric fields was analyzed from the separate contributions of the dielectric constant (ε) and remanent polarization (Pr) based on the Maxwell relation. Consideration of the contributions of both ε and Pr is particularly important in a unipolar electric field operation, such as on/off field switching used in device applications. Direct ΔT measurements were also performed based on the lock-in thermography technique to verify the accuracy of the ΔT intensity estimated by the indirect method. The indirect and direct ΔT values were largely consistent. The ΔT intensity near the peak temperature of ΔT was dominated by the Pr contribution; a large ∂Pr/∂T was necessary to increase the overall ΔT magnitude. In contrast, a large ∂ε/∂T was essential to expand the operating temperature range of ΔT at temperatures higher than the dielectric maximum temperature. Quantitative understanding of the contributions of both ε and Pr to ΔT in unipolar electric fields is expected to guide the search for materials with a superior ECE.

DOI： 10.1063/5.0259805

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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 Society of Powder and Powder Metallurgy  

DOI： 10.2497/jjspm.15f-t14-02

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開催年月日： 2025年6月

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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開催年月日： 2025年6月

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記述言語：英語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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開催年月日： 2025年10月

記述言語：日本語   会議種別：口頭発表（一般）  

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開催年月日： 2025年9月

記述言語：英語   会議種別：ポスター発表  

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開催年月日： 2025年9月

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国名：日本国  

開催年月日： 2025年9月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2025年9月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2025年9月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2025年9月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2025年9月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国