Doping Effects on the Migration of Oxygen Vacancies in Lanthanum Strontium Manganite Compound

DILSON JUAN; PRUNEDA MANUEL; HUNT DIEGO; VALERIA FERRARI

Bariloche

Simposio; Simposio Latinoamericano de F ́ısica del Estado S ́olido - SLAFES XXIII; 2018

Complex manganese oxides have been the subject of intense study for decades due to the discovery ofboth intrinsic and extrinsic properties such as colossal magnetoresistance, ferroelectricity, and metal-insulator transitions, among others. They are all modulated by factors such as the amount of doping,structural strain, crystal defects and the presence of surfaces and interfaces. This variety of propertiespromises several technological applications for manganites. Recently, this material has been extensivelyused as cathode in solid oxide fuel cells (SOFCs), a clean energy generation technology which takesadvantage of particular characteristics regarding the chemical and structural stability, ionic-electronicconductivity and catalytic activity of manganites.In this work, we present a study about the diffusion of oxygen vacancies, focusing on the role of Sr-dopingin the formation energies and migration barriers in La(1-x)SrxMnO3 compounds by means of the DensityFunctional Theory (DFT) and the Nudged Elastic Band (NEB) method. The distribution of Sr ions withinthe crystal structure is obtained using the approach of Special Quasirandom Structures (SQS). We focus ona range of composition 0.20 < x < 0.50 which includes doping concentrations most frequently used inSOFCs.We show that the effect of local and global doping infuences both the electronic bandstructure and theenergy formation energies leading to two distinct regimes, displaying either a deep defect state or ashallow band-like state close the conduction band