Phase stability and electrochemical properties of Fe-doped LSGM solid electrolyte for IT-SOFCs = Fe가 치환된 LSGM 중저온형 고체전해질의 상안정성과 전기화학특성에 관한 연구

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$La_{0.8}Sr_{0.2}Ga_{0.8}Mg_{0.2}O_{3-\delta}$ (LSGM8282) perovskites show superior ionic conductivity and chemical stability, and are regarded as promising candidates for the electrolyte of intermediate temperature solid oxide fuel cells (IT-SOFCs). Efficiency of fuel cell using LSGM is related to the electrical conductivity of the electrolyte, since the minor charge carriers in the electrolyte, i.e., free electrons and electron holes, could result to a short circuit current. The studies of the conductivity of LSGM with a low concentration of transition metal ($\lt 8.5 mol%$) are still limited. Ishihara et al. investigated the electronic conductivity in cobalt doped LSGM with the ion blocking method. Electronic conductivities at various temperatures in $La_{0.8}Sr_{0.2}Ga_{0.8}Mg_{0.15}Co_{0.05}O_{3-\delta}$ (LSGMC5) and electronic conductivities at in LSGM8282 doped with various amount of cobalt were reported. It was considered that minor free electron and hole conductivity caused by the redox reactions. The properties of the single cell have a strong effect on the polarization resistance of the electrode supported on the electrolyte beside the dominant effect on the ohmic resistance of the cell. The single cells with transition metal doped lanthanum gallate electrolyte exhibited a low ohmic resistance and electrode polarization resistance. It was assumed that the properties of the charge carriers in the electrolyte could play a major role in determining the cell performance In chapter III, we discuss the phase stability and conductivity of Fe-doped LSGM with a “Sr-rich” composition (25 mol%), or $La_{0.75}Sr_{0.25}Ga_{0.8}Mg_{0.2 -x}Fe_xO_{3-\delta}$ (x = 0-0.08) and report the results of optimized composition for a promising electrolyte composition. It is of significance to systematically investigate the crystal structure, because the investigation brings the useful information to examine the oxide ion conduction mechanism. Thus we crystallographic analys...
Advisors
Kim, Ho-Giresearcher김호기researcher
Description
한국과학기술원 : 신소재공학과,
Publisher
한국과학기술원
Issue Date
2010
Identifier
418663/325007  / 020055102
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 신소재공학과, 2010. 2, [ ix, 128 p. ]

Keywords

Electrolyte; reitveld refinement; lanthanum gallate; 고체산화물 연료전지; 전해질; 리트벨트 구조분석; 란타늄 갈레이트; LSGM; solid oxide fuel cell

URI
http://hdl.handle.net/10203/49727
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=418663&flag=dissertation
Appears in Collection
MS-Theses_Ph.D.(박사논문)
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