Kang-neung, South Korea
Kang-neung, South Korea

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Kim Y.-H.,Gangneung - Wonju National University | Kim S.,Hasla Co. | Jeong S.-M.,Korea Institute of Ceramic Engineering And Technology | Kim S.-J.,Hanzhong University | Yoon S.-O.,Gangneung - Wonju National University
Journal of the Korean Ceramic Society | Year: 2015

Phase evolution, microstructure, and microwave dielectric properties of Li2O and Al2O3 doped Zn1.9Si1.05O4, i.e., Zn1.9-2xLixAlxSi1.05O4, ceramics (x = 0.02 ∼ 0.10) were investigated. The ceramics were densified by SiO2-rich liquid phase composed of the Li-Al- Si-O system, indicating that doped Li and Al contributed to the formation of the liquid. As the secondary phase, β-spodumene solid solution with the composition of LiAlSi3O8 was precipitated from the liquid during the cooling process. The dense ceramics were obtained for the specimens of ≥ 0.06 showing the rapid densification above 1000°C, implying that a certain amount of liquid is necessary to densify. The specimen of x = 0.06 sintered at 1050°C exhibited good microwave dielectric properties; the dielectric constant and the quality factor (Q × f0) were 6.4 and 11,213 GHz, respectively.

Byeon D.-S.,Korea Institute of Ceramic Engineering And Technology | Byeon D.-S.,Yonsei University | Jeong S.-M.,Korea Institute of Ceramic Engineering And Technology | Hwang K.-J.,Korea Institute of Ceramic Engineering And Technology | And 5 more authors.
Journal of Power Sources | Year: 2013

A computational study employing classical molecular dynamics techniques was employed to explore the diffusion of oxide ions in Ba-doped LaInO3, a cubic perovskite oxide. The Ba dopant in the LaInO3 forms oxygen vacancies that function as charge carriers via an oxygen diffusion mechanism. Previous experimental studies reported that the ionic conductivity of Ba-doped LaInO3 decreases with increasing numbers of oxygen vacancies, which was not fully understood through experimental approaches. Hence, this study explored the diffusion pathway for individual oxygen vacancies through molecular dynamics simulation. Based on the findings of this study, the Ba dopant appears to form narrow bottlenecks that function as a barrier to the movement of oxide ions. We concluded that the oxide ion conductivity of Badoped LaInO3 is affected by the local ionic distribution of the Ba dopant. © 2012 Elsevier B.V. All rights reserved.

Kim H.-L.,Yonsei University | Kim S.,Hasla Co. | Lee K.-H.,Kangwon National University | Lee H.-L.,Yonsei University | Lee K.-T.,Chonbuk National University
Journal of Power Sources | Year: 2014

Oxygen ion conduction behaviors of the 0-5 mol% excess Ba-doped La 0.6Ba0.4InO3-δ cubic perovskite oxides have been investigated to elucidate their potential as electrolyte materials. The highest conductivity, 5.6 × 10-2 S cm-1 at 800 °C, is obtained at the 3 mol% excess Ba-doped composition benefiting from a supplementation of Ba2+ ions on the vacant A-site generated by the volatilization during the heat-treatment processes. Interestingly, all the samples except the undoped composition show curved electrical conductivity behavior in the Arrhenius plot. The activation energy is 0.50-0.52 eV in the high-temperature region above 900 °C, which is slightly lower than that of the doped LaGaO3 system. Moreover, all the samples show significantly lower activation energy values of both the high- and low-temperature regions compared with yttria-stabilized zirconia. The 3 mol% excess Ba-doped La 1-xBaxInO3-δ (0.4 ≤ x ≤ 0.8) sample has also been studied. All of the compositions show a cubic perovskite structure and a nearly pure oxygen ion conduction behavior in a dry atmosphere even when p(O2) = 1atm. The composition of x = 0.4 exhibits the highest oxygen ion conductivities. © 2014 Elsevier B.V. All rights reserved.

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