| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1296225 | Solid State Ionics | 2011 | 8 Pages |
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.
Research highlights► Smooth, flat (100), (110), and (111) oriented La0.7Sr0.3MnO3 films were fabricated with PLD. ► All films had surface dominated responses in electrical conductivity relaxation measurements. ► From 600 to 800 °C, chemical exchange coefficients varied from Kchem ≈ 1 to 65 × 10− 6 cm/s. ► The activation energy of Kchem varied: E(110) ≈ 1.16 eV, and E(111) and E(100) ≈ 0.83 eV. ► At 800 °C, a 4-fold variation in Kchem was observed, with (110) the highest and (100) the lowest.
