“…Independent works from Fleig's and Tarancón's groups recently discovered fast oxide-ionic conductivity along grain boundaries in LSM, reporting up to 5-6 orders of magnitude of improvement in oxide-ion diffusivity compared to the bulk, which might be associated to straininduced defects and corresponding changes in the oxidation states of LSM constituent cations [6,31]. In this sense, dominating ionic conductivity at the grain boundary level was reported for PLD-growth thin films of La0.8Sr0.2Mn1-xCoxO3±δ [103], LaCo0.6Ni0.4O3 [104] and consistently from Develos-Bagarinao et al for YSZ, CGO, La0.6Sr0.4Co0.2Fe0.8O3-δ and La0.6Sr0.4CoO3-δ [105,106].…”