The University of Osaka · 재료과학
이 교수의 연구실은 고체 이온 도전성 물질과 나노구조 산화물의 설계 및 응용을 핵심으로 하며, 특히 트리바렌트 이온(Sc³⁺, Ce⁴⁺, Mg²⁺ 등)의 이동 거동을 제어하는 고체 전해질 소재 개발에 집중하고 있습니다. 다양한 금속 산화물 및 포스페이트 기반의 비정질 및 단결정 물질을 통해 전도도 향상, 표면 개질, 나노입자 제어를 실현하고 있으며, 특히 자외선 차단제, 고온 이온 전도체, 투명 도막 등 응용 가능성을 탐색하고 있습니다. 연구는 고체화학적 설계 원리와 정밀한 물성 측정 기법을 융합하여, 안정성과 기능성을 동시에 확보한 신소재 개발을 목표로 합니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
A series of amorphous phosphates of Ce1-xTixP2O7 has been developed as a band gap tunable inorganic material. The optical absorption edge can be tuned through the desired range in the ultraviolet region by simple composition adjustments. This amorphous material consists of harmless elements and is a promising safety sunscreen agent.
To realize a trivalent ion conduction in solids, the Sc2(WO4)3-type structure was chosen on the basis of the mobile trivalent ions and the structure which reduces the electrostatic interaction between the framework and the mobile trivalent ionic species as much as possible. The typical conductivity of the rare earth tungstates R2(WO4)3 (R = Sc, Y, and Er−Lu) with the Sc2(WO4)3-type structure was found to be on the order of 10-5 S cm-1 at 600 °C. Among the rare earth tungstates, Sc2(WO4)3 (σ600°C
Abstract In order to realize a higher valency ion conduction in solids, the Sc2(WO4)3 material which possesses a larger tunnel size for ion migration was selected to reduce the electrostatic interaction and the single crystals of Sc2(WO4)3 were grown to eliminate grain boundary effects found in polycrystalline state. By both the alternative and direct current measurements, a direct evidence of Sc3+ trivalent ion migration in single crystal Sc2(WO4)3 has been successfully demonstrated.
Calcium doping levels of up to 20 % can be achieved for the La1−xCaxOCl1−x solid solution series. At the highest doping levels (x=0.2; see graph (•)), the conductivity of the solid solution is three orders of magnitude greater than that of undoped LaOCl (□). The potential for the design of new functional materials stems from their high thermal stability, relative density, and hardness, in addition to their insolublity in water.
A method based on a hydrothermal process was applied to obtain not only ultrafine but also well-dispersed CeO2 nanoparticles by the application of citric acid as a protective agent against particle growth. The well-defined crystallites have a narrow size distribution, and the mean size and BET specific surface area are 3.1 nm and 211 m2 g−1, respectively. A mixture of the condensation product of boric acid and 2,2′-iminodiethanol (diethanolamine) and cerium oxide nanoparticles has been found to
The divalent Mg2+ ion conducting solid electrolyte was synthesized with a composite form by intentionally changing the starting material mixing ratio to the nonstoichiometric region. By such a preparation technique, spontaneous and microscopic dispersion of the secondary Zr2O(PO4)2 phase was successfully realized and the Mg2+ ion conductivity was considerably enhanced by dispersing the secondary phase, showing the highest conductivity among the Mg2+ ionic conducting solid electrolytes reported.
Silver powder was mixed with a Y-Ba-Cu-O superconductor so as to improve its critical current density, J c . The J c of YBa 2 Cu 3 O 7- x with silver (3 wt%) was twice that without silver. T c (end point) was almost constant around 90 K in spite of the silver mix. The decrease of T c (end point) with magnetic flux was greatly inhibited by the silver mixing.
Single crystals of the trivalent Al3+ ion conductor Al2(WO4)3 were grown by the Czochralski (CZ) method. The ionic conductivity in the a-, b-, and c-axis directions was determined and Al3+ ion conduction in the direction of the b-axis was concluded to be the most suitable pathway for ion migration in the tungstate grains. The ionic conductivities in the a- and c-axis directions were 0.3 and 10-2 times lower than the conductivity in the b-axis. Consistent with this observation, the lowest activat
Direct decomposition of NO into N2 and O2 on a C-type cubic (Gd1–x–yYxBay)2O3–y solid solution catalyst is investigated. These novel catalysts are found to exhibit higher activity and conversion rates than conventional La-containing perovskite oxide catalysts for NO decomposition. C-type cubic (Gd1–x–yYx-Bay)2O3–y catalysts are therefore considered to be possible candidates for the conversion of harmful exhaust gases. Supporting information for this article is available on the WWW under http://w
Abstract A carbon dioxide gas sensor probe was fabricated by applying a high lithium ionic conductor as a solid electrolyte and a calcium carbonate + calcium oxide mixture as a solid reference electrode, and its ability for CO2 detection was examined. The electromotive force(EMF) obtained was in excellent agreement with the EMF value calculated from the Nernst’s equation for CO2 gas concentrations from 80 ppm(v/v) to 1 %(v/v).
