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

JUAN, DILSON; PRUNEDA, JOSÉ MIGUEL; FERRARI, VALERIA; HUNT, DIEGO

Trieste, Italia

Workshop; Workshop on Crystal Structure Prediction: Exploring the Mendeleev Table as a Palette to Design New Materials; 2019

The Abdus Salam International Centre for Theoretical Physics (ICTP)

p { margin-bottom: 0.1in; line-height: 120%; }Complexmanganese oxides have been the subject of intense study for decadesdue to the discovery of both intrinsic and extrinsic properties suchas colossal magnetoresistance, ferroelectricity, and metal-insulatortransitions, among others. They are all modulated by factorssuch as the amount of doping, structural strain, crystal defects andthe presence of surfaces and interfaces. This variety of propertiespromises several technological applications for manganites. Recently,this material has been extensively used as cathode in solid oxidefuel cells (SOFCs), a clean energy generation technology which takesadvantage of particular characteristics regarding the chemical andstructural stability, ionic-electronic conductivity and catalyticactivity of manganites.Inthis work, we present a study about the diffusion of oxygenvacancies, focusing on the role of Sr-doping in the formationenergies and migration barriers in La(1-x)SrxMnO3 compounds by means of theDensity Functional Theory (DFT) and the Nudged Elastic Band (NEB)method. The distribution of Sr ions within the crystal structureis obtained using the approach of Special Quasirandom Structures(SQS). We focus on a range of composition 0.20<x<0.50which includes doping concentrations most frequently used in SOFCs. Weshow that the effect of local and global doping influence both theelectronic bandstructure and the energy formation energies leading totwo distinct regimes, displaying either a deep defect state or ashallow band-like state close the conduction band.