Enhanced shrinkage of lanthanum strontium manganite (La 0.90Sr0.10MnO3+δ) resulting from thermal and oxygen partial pressure cycling

Benjamin P. McCarthy, Larry R. Pederson, Harlan U. Anderson, Xiao Dong Zhou, Prabhakar Singh, Gregory W. Coffey, Edwin C. Thomsen

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Abstract

Exposure of (La0.90Sr0.10)0.98MnO 3+δ (LSM-10) to repeated oxygen partial pressure cycles (air/10 ppm O2) resulted in enhanced densification rates, similar to behavior shown previously due to thermal cycling. Shrinkage rates in the temperature range 700°-1000°C were orders of magnitude higher than Makipirtti-Meng model estimations based on stepwise isothermal dilatometry results at a high temperature. A maximum in enhanced shrinkage due to oxygen partial pressure cycling occurred at 900°C. Shrinkage was the greatest when LSM-10 bars that were first equilibrated in air were exposed to gas flows of lower oxygen fugacity than in the reverse direction. The former creates transient cation and oxygen vacancies well above the equilibrium concentration, resulting in enhanced mobility. These vacancies annihilate as Schottky equilibria are reestablished, whereas the latter condition does not lead to excess vacancy concentrations.

Original languageEnglish
Pages (from-to)3255-3262
Number of pages8
JournalJournal of the American Ceramic Society
Volume90
Issue number10
DOIs
Publication statusPublished - Oct 2007
Externally publishedYes

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ASJC Scopus subject areas

  • Ceramics and Composites

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