Effects of crystallographic orientation on the oxygen exchange rate of La0.7Sr0.3MnO3 thin films |
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Authors: | Lu YanKR Balasubramaniam Shanling WangHui Du Paul A Salvador |
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Institution: | Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, USA |
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Abstract: | The oxygen surface exchange of La0.7Sr0.3MnO3 (LSM) thin films was investigated using the electrical conductivity relaxation (ECR) method. Epitaxial (100)-, (110)-, and (111)-oriented LSM films were fabricated on corresponding SrTiO3 (STO) substrates using pulsed laser deposition. The LSM films had well-controlled surface qualities, exhibited bulk-like steady-state electrical properties, and exhibited surface dominated responses in ECR. The chemical surface exchange coefficients (kchem) were determined and varied from ≈ 1 × 10− 6 to 65 × 10− 6 cm/s, depending on temperature and orientation, with activation energies of between 0.8 and 1.2 eV. At 800 °C, a four fold variation is observed in the kchem values, with (110)/(100) being the highest/lowest, explained well by the high activation energy for (110), ≈ 1.16 eV, and the low energy for (111) and (100), ≈0.83 eV. |
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Keywords: | Surface exchange Thin films Solid oxide fuel cells (La Sr)MnO3 |
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