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Low‐Temperature Densification of Lanthanum Strontium Manganite (La 1− x Sr x MnO 3+δ ), x =0.0–0.20
Author(s) -
McCarthy Benjamin P.,
Pederson Larry R.,
Williford Ralph E.,
Zhou XiaoDong
Publication year - 2009
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2009.03082.x
Subject(s) - lanthanum manganite , sintering , isothermal process , strontium , lanthanum , analytical chemistry (journal) , materials science , manganite , oxygen , activation energy , diffusion , mineralogy , chemistry , inorganic chemistry , metallurgy , thermodynamics , electrolyte , physics , organic chemistry , electrode , chromatography , quantum mechanics , ferromagnetism
Intermediate‐stage sintering of lanthanum strontium manganite (LSM, where Sr=0.00, 0.05, 0.10, 0.15, and 0.20) was shown in dilatometry studies to be accelerated when subjected to alternating flows of air and nitrogen. The extent of rate enhancement decreased with increased Sr content, and decreased with increased temperature, which coincides with diminished oxygen nonstoichiometry. Shrinkage rates were further shown to be sensitive to the difference in oxygen content in the alternating gas flows. Baseline air sintering rates were measured using stepwise isothermal dilatometry, from which kinetic parameters were calculated using the Makipirtti–Meng model. Activation energies for sintering in air were determined to be 255 ± 26, 258 ± 28, 308 ± 32, 373 ± 37, and 417 ± 41 kJ/mol for Sr=0.0, 0.05, 0.10, 0.15, and 0.20, respectively. A diffusion‐based model is proposed that is consistent with trends in accelerated shrinkage versus temperature. Transient cation vacancy gradients, which lead to higher cation mobility, were calculated from established oxygen diffusivities and oxygen nonstoichiometry as a function of temperature and time. A potential application of this approach is the processing of LSM‐based cathode‐side contact pastes in solid oxide fuel cells.

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