https://scholar.dgist.ac.kr/handle/20.500.11750/255 Tue, 12 May 2026 12:16:50 GMT 2026-05-12T12:16:50Z https://scholar.dgist.ac.kr/handle/20.500.11750/56372 Title: Defect chemistry of highly defective La0.1Sr0.9Co0.8Fe0.2O3-Delta by considering oxygen interstitials Author(s): Im, Ha Ni; Singh, Bhupendra P.; Hong, Jae Woon; Kim, In Ho; Lee, Kang Taek; Song, Sun Ju Abstract: In case of highly defective perovskite oxides such as La0.1Sr0.9Co0.8Fe0.2O3-δ (LSCF1982), the ionic defect has been in question by suggesting direct oxygen ion diffusion by considering lattice oxygen site as an interstitial rather than an oxygen vacancy. In the present study, the thermomigration of ionic defect species was measured by ionic thermopower measurement to provide strong evidence of interstitial diffusion and the defect structure was further analyzed in terms of effectively negatively charged oxygen interstitial as a charge-compensating defect against hole. Two kinds of holes-delocalized and localized at B-site cations; were investigated by defect chemical analysis. From the conductivity analysis based on the non-stoichiometry results, the contributions of delocalized holes, localized hole at Co site, localized hole at Fe site, and localized hole moving from Co site to Fe site were successfully separated, and it was observed that the hopping reaction involving hole localized at Co is dominant in conductivity mechanism. The measurement of electronic thermopower further confirms the involvement of two different types of holes in p-type conduction. © 2016 The Electrochemical Society. All rights reserved. Thu, 31 Dec 2015 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/56372 2015-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/15531 Title: In-situ exsolution of Ni nanoparticles to achieve an active and stable solid oxide fuel cell anode catalyst on A-site deficient La0.4Sr0.4Ti0.94Ni0.06O3-δ Author(s): Lee, Jong Jun; Kim, Kyeounghak; Kim, Kyeong Joon; Kim, Hyung Jun; Lee, Yong Min; Shin, Tae Ho; Han, Jeong Woo; Lee, Kang Taek Abstract: (La,Sr)TiO3 has been investigated as a promising anode material for solid oxide fuel cells (SOFCs) owing to its high electronic conductivity and superior phase stability. However, the low catalytic activity of (La,Sr)TiO3 materials is a major obstacle to the application of SOFCs. Exsolution has emerged as an effective strategy to overcome the low catalytic activity of (La,Sr)TiO3 materials. In this work, Ni-doped A-site-deficient La0.4Sr0.4TiO3-δ (LST) (i.e., La0.4Sr0.4Ti0.94Ni0.06O3-δ; LSTN) with in-situ exsolved Ni nanoparticles (NPs) was developed and the effects of exsolved Ni NPs on H2 oxidation was investigated. The doped Ni was exsolved and formed NPs on the LSTN surface under reducing conditions. Owing to the high catalytic activity of the exsolved Ni NPs, the SOFC with LSTN-Ce0.9Gd0.1O2-δ (GDC) yielded a maximum power density of 0.46 W cm−2 at 850°C, 91% higher than that of the cell with LST-GDC, as well as high long-term and redox stability. Furthermore, density functional theory calculations revealed that the adsorption and dissociation of H2 were more favorable for exsolved Ni NPs than for pure Ni owing to the more positively charged surface of the exsolved Ni NPs in the LSTN. These results demonstrated that exsolution is an effective method for improving the electrocatalytic activity of perovskite (La,Sr)TiO3 materials. © 2021 The Korean Society of Industrial and Engineering Chemistry Sun, 31 Oct 2021 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/15531 2021-10-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/15503 Title: In Situ Synthesized La0.6Sr0.4Co0.2Fe0.8O3-delta-Gd0.1Ce0.9O1.95 Article Nanocomposite Cathodes via a Modified Sol-Gel Process for Intermediate Temperature Solid Oxide Fuel Cells Author(s): Joh, Dong Woo; Cha, Areum; Park, Jeong Hwa; Kim, Kyeong Joon; Bae, Kyung Taek; Kim, Doyeub; Choi, Young Ki; An, Hyegsoon; Shin, Ji Su; Yoon, Kyung Joong; Lee, Kang Taek Abstract: Composite cathodes comprising nanoscale powders are expected to impart with high specific surface area and triple phase boundary (TPB) density, which will lead to better performance. However, uniformly mixing nanosized heterophase powders remains a challenge due to their high surface energy and thus ease with which they agglomerate into their individual phases during the mixing and sintering processes. In this study, we successfully synthesized La0.6Sr0.4Co0.2Fe0.8O3-? (LSCF)-Gd0.1Ce0.9O1.95 (GDC) composite cathode nanoscale powders via an in situ sol-gel process. High-angle annular dark field scanning transmission electron microscopy analysis of in situ prepared LSCF-GDC composite powders revealed that both the LSCF and GDC phases were uniformly distributed with a particle size of ?90 nm without cation intermixing. The in situ LSCF-GDC cathode sintered on a GDC electrolyte showed a low polarization resistance of 0.044 ω cm2 at 750 °C. The active TPB density and the specific two phase (LSCF/pore) boundary area of the in situ LSCF-GDC cathode were quantified via a 3D reconstruction technique, resulting in 12.7 μm-2 and 2.9 μm-1, respectively. These values are significantly higher as compared to reported values of other LSCF-GDC cathodes, demonstrating highly well-distributed LSCF and GDC at the nanoscale. A solid oxide fuel cell employing the in situ LSCF-GDC cathode yielded excellent power output of ?1.2 W cm-2 at 750 °C and high stability up to 500 h. Copyright © 2018 American Chemical Society. Thu, 31 May 2018 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/15503 2018-05-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/13490 Title: Piezoelectric Nanogenerator Based on Lead-Free Flexible PVDF-Barium Titanate Composite Films for Driving Low Power Electronics Author(s): Sahu, Manisha; Hajra, Sugato; Lee, Kang Taek; Deepti, PL; Mistewicz, Krystian; Kim, Hoe Joon Abstract: Self‐powered sensor development is moving towards miniaturization and requires a suitable power source for its operation. The piezoelectric nanogenerator (PENG) is a potential candidate to act as a partial solution to suppress the burgeoning energy demand. The present work is focused on the development of the PENG based on flexible polymer‐ceramic composite films. The X‐ray spectra suggest that the BTO particles have tetragonal symmetry and the PVDF‐BTO composite films (CF) have a mixed phase. The dielectric constant increases with the introduction of the particles in the PVDF polymer and the loss of the CF is much less for all compositions. The BTO particles have a wide structural diversity and are lead‐free, which can be further employed to make a CF. An attempt was made to design a robust, scalable, and cost‐effective piezoelectric nanogenerator based on the PVDF‐BTO CFs. The solvent casting route was a facile approach, with respect to spin coating, electrospinning, or sonication routes. The introduction of the BTO particles into PVDF enhanced the dielectric constant and polarization of the composite film. Furthermore, the single‐layered device output could be increased by strategies such as internal polarization amplification, which was confirmed with the help of the polarization‐electric field loop of the PVDF‐ BTO composite film. The piezoelectric nanogenerator with 10 wt% BTO‐PVDF CF gives a high electrical output of voltage 7.2 V, current 38 nA, and power density of 0.8 μW/cm2 at 100 MΩ. Finally, the energy harvesting using the fabricated PENG is done by various actives like coin dropping, under air blowing, and finger tapping. Finally, low‐power electronics such as calculator is successfully powered by charging a 10 μF capacitor using the PENG device. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Sun, 31 Jan 2021 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/13490 2021-01-31T15:00:00Z