Solid oxide fuel cells (SOFC) are under intensive investigation since the 1980's as these devices open way for ecologically clean direct conversion of chemical energy into electricity, avoiding efficiency limitation by Carnot's cycle thermochemical conversion. However, practical development SOFC faces a number unresolved fundamental problems, in particular concerning kinetics electrode reactions, especially oxygen reduction reaction. We review recent experimental and theoretical achievements...

An extensive set of DFT calculations on LaMnO3 slabs has been generated and used as a basis to identify the most probable reaction mechanism for oxygen incorporation into (La, Sr)MnO3−δ cathode materials. MnO2[001] is found be stable surface termination under fuel cell operation conditions (high temperature, high pO2, cubic unit cell). Chemisorption leading formation O2−, O22−, O− atop Mn exothermic, but due negative adsorption entropy electrostatic repulsion levels coverage molecular...

The atomic and electronic structure, formation energy, the energy barriers for migration have been calculated neutral O vacancy point defect ($F$ center) in cubic $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$ employing various implementations of density functional theory (DFT). Both bulk $\mathrm{Ti}{\mathrm{O}}_{2}$-terminated (001) surface $F$ centers considered. Supercells different shapes containing up to 320 atoms employed. limit an isolated single oxygen corresponds a 270-atom supercell,...

The formation and migration of oxygen vacancies in the series (La,Sr)(Co,Fe)O(3-δ) perovskites, which can be used as mixed conducting SOFC cathode materials permeation membranes, are explored detail by means first principles density functional calculations. Structure distortions, charge redistributions transition state energies during ion obtained analyzed. Both overall chemical composition vacancy energy found to have only a small impact on barrier; it is rather local cation configuration...

We present and discuss the results of ab initio DFT plane-wave supercell calculations atomic molecular oxygen adsorption diffusion on LaMnO(3) (001) surface which serves as a model material for cathode solid oxide fuel cells. The dissociative O(2) molecules from gas phase is energetically favorable Mn ions even defect-free surface. migration energy adsorbed O found to be quite high, 2.0 eV. predict that atoms could penetrate electrode first plane when much more mobile vacancies (migration...

Based on first principles DFT calculations, we analyze oxygen vacancy formation and migration energies as a function of chemical composition in complex multicomponent (Ba,Sr)(Co,Fe)O3−δ perovskites which are candidate materials for SOFC cathodes permeation membranes. The atomic relaxation, electronic charge redistribution the transition states compared several to elucidate atomistic reason exceptionally low barrier Ba0.5Sr0.5Co0.8Fe0.2O3−δ that was previously determined experimentally....

We compare two approaches to the atomic, electronic, and magnetic structures of $\mathrm{La}\mathrm{Mn}{\mathrm{O}}_{3}$ bulk (001), (110) surfaces---hybrid B3PW with optimized LCAO basis set (CRYSTAL-2003 code) GGA-PW91 plane-wave (VASP 4.6 code). Combining our calculations those available in literature, we demonstrate that combination nonlocal exchange correlation used hybrid functionals allows reproduce experimental coupling constants ${J}_{ab}$ ${J}_{c}$ as well optical gap. Surface...

The results of the first principles spin-polarized DFT calculations atomic and electronic structure a complex perovskite (Ba1-xSrx)(Co1-yFey)O3-δ (BSCF) used as cathode material for solid oxide fuel cells (SOFC) gas separation membranes are presented discussed. formation energies oxygen vacancies found to be considerably smaller than in other magnetic perovskites, e.g. (La,Sr)MnO3, which explains experimentally observed strong deviation this from stoichiometry. presence induces local charge...

First principles density functional theory modeling of point defects and structural disordering in BaxSr1–xCoyFe1–yO3−δ (BSCF) perovskites reveals that the material tends to decompose at low temperatures into a mixture cubic hexagonal perovskite and/or oxide phases. Special attention is paid elucidating effects oxygen nonstoichiometry on phase stability, decomposition energies, vacancy formation energies. The observed lattice instability likely negate advantages fast transport chemistry...

In this work, an interatomic potential for the W-Re system is fitted and benchmarked against experimental density functional theory (DFT) data, of which part are generated in work. Having mind studies related to plasticity alloys under irradiation, emphasis put on fitting point-defect properties, elastic constants, dislocation properties. The developed can reproduce mechanisms responsible experimentally observed softening, i.e., decreasing shear moduli, Peierls barrier, asymmetric screw core...

The interaction of H or He atoms with a core edge and screw dislocations (SDs), Burgers vector 0/2, is studied by means ab initio calculations. results show that the are stronger traps for compared to SDs, while H/He affinity both types dislocation significantly weaker than single vacancy. lowest energy atomic configurations rationalized on basis charge density distribution elasticity theory considerations. obtained contribute rationalization thermal desorption spectroscopy analysis...

The surface polarity of (La,Sr)O and MnO₂ (001) terminations drastically affects defect adsorbate concentrations, resulting in strongly different oxygen exchange rates.

In the present work, we investigate potential of modified barium titanate (BaTiO3), an inexpensive perovskite oxide derived from earth-abundant precursors, for developing efficient water oxidation electrocatalysts using first-principles calculations. Based on our calculations, Rh doping is a way making BaTiO3 absorb more light and have less overpotential needed to oxidize. It has been shown that TiO2-terminated (001) surface promising point view its use as catalyst. expands spectrum absorbed...

Atomic scale density functional calculations are used to predict the behaviour of defects in uranium mononitride (UN). Two different codes (VASP and CASTEP) were employed with supercells containing from 8 250 atoms (providing a significant range defect concentrations). Schottky nitrogen Frenkel point formation energies, local lattice relaxations overall parameter change, as well induced electronic redistribution, discussed.

We present the results of ab initio DFT plane wave periodic structure calculations LaMnO3 (001) surface. The effects related to three different kinds pseudopotentials, slab thickness, magnetic ordering, and surface relaxation are studied discussed. antiferromagnetic lowest in energy (that is, spins on Mn ions parallel basal antiparallel from plane) has a considerable atomic up fourth calculated (Bader) effective charges electronic density maps demonstrate reduction atom ionicity accompanied...

(Ba,Sr)(Co,Fe)O3 (BSCF) perovskite solid solutions are promising materials for oxide fuel cell cathodes and oxygen permeation membranes. Cathode performance strongly depends on the morphology of these remaining as a single phase or two-phase mixture. Combining ab initio calculations atomic electronic structure different supercells with thermodynamics solutions, we have constructed discussed diagrams several important BSCF chemical compositions. It is demonstrated that in BSC cobaltite...

The interaction of carbon atoms with point defects and the core edge screw dislocations Burgers vector a0/2⟨111⟩ in W a W-Re matrix is studied by means ab initio calculations. structure energetics ground-state atomic configurations are presented rationalized. It found that di-vacancies, which thermally unstable pure according to state-of-the-art calculations, can nucleate at C Re-C complexes, fill gap explanation emergence nanovoids observed experimentally under irradiation. Also, on basis...

Abstract In this paper we present and discuss the results of first first‐principle modelling point defects in nitride nuclear fuels. Calculations have been performed using VASP computer code combined with supercells containing up to 250 atoms. The effective atomic charges, electronic density redistribution, displacements around U N vacancies their formation energies are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)