Solid oxide fuel cells (SOFC) are under intensive investigation since the 1980's as these devices open the way for ecologically clean direct conversion of the chemical energy into electricity, avoiding the efficiency limitation by Carnot's cycle for thermochemical conversion. However, the practical development of SOFC faces a number of unresolved fundamental problems, in particular concerning the kinetics of the electrode reactions, especially oxygen reduction reaction. We review recent experimental and theoretical achievements in the current understanding of the cathode performance by exploring and comparing mostly three materials: (La,Sr)MnO3 (LSM), (La,Sr)(Co,Fe)O3 (LSCF) and (Ba,Sr)(Co,Fe)O3 (BSCF). Special attention is paid to a critical evaluation of advantages and disadvantages of BSCF, which shows the best cathode kinetics known so far for oxides. We demonstrate that it is the combined experimental and theoretical analysis of all major elementary steps of the oxygen reduction reaction which allows us to predict the rate determining steps for a given material under specific operational conditions and thus control and improve SOFC performance.

Native and impurity point defects in both yttrium aluminium perovskite (YAP) and garnet (YAG) crystals are studied in the framework of the pair-potential approximation coupled with the shell model description of the lattice ions. The calculated formation energies for native defects suggest that the antisite disorder is preferred over the Frenkel and Schottky-like disorder in both YAP and YAG. The calculated values of the distortion caused by the antisite Y x Al in the lattice turn out to be in an excellent agreement with the EXAFS measurements. In non-stoichiometric compounds, the calculated reaction energies indicate that excess Y 2 O 3 or Al 2 O 3 is most likely to be accommodated by the formation of antisites rather than vacancies or interstitials in the lattice. Enthalpies of the reactions for impurity (Ca 2+ , Mg 2+ , Sr 2+ , Ba 2+ , Cr 3+ , Fe 3+ , Nd 3+ , Si 4+ ) incorporation into both YAP and YAG lattices are calculated. The relevant experimental data are discussed.

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Line-imaging velocimetry for observing spatially heterogeneous mechanical and chemical responses in plastic bonded explosives during impact Rev. Sci. Instrum. 84, 083903 (2013); 10.1063/1.4817307 Band-gap tuning at the strong quantum confinement regime in magnetic semiconductor EuS thin films Appl. Phys. Lett. 100, 211910 (2012); 10.1063/1.4720167Compression-induced effect on the electronic structure of cyclotrimethylene trinitramine containing an edge dislocation A novel mechanism for detonation initiation in solid explosives is proposed. This is based on electronic excitations induced by an impact wave propagating through the crystal. We illustrate the model by using the RDX ͑C 3 H 6 N 6 O 6 ) crystal as an example. In our model, a key role belongs to lattice defects, in particular edge dislocations, which promote dramatic changes in the electronic structure, primarily a reduction of the optical gap due to the splitting off of local electronic states from both valence and conduction bands. The pressure inside the impact wavefront further reduces the band gap, making it close to zero. This promotes highest occupied molecular orbital-lowest unoccupied molecular orbital HOMO-LUMO transitions resulting in N-NO 2 bond breaking and the creation of favorable conditions for the initiation of a chain reaction. Experimental facts supporting the suggested mechanism are discussed.

Dimethyl methylphosphonate (DMMP) is a common chemical warfare agent simulant and is widely used in adsorption studies. To further increase the understanding of DMMP interactions with metal oxides, ambient pressure X-ray photoelectron spectroscopy was used to study the adsorption of DMMP on MoO3, including the effects of oxygen vacancies, surface hydroxyl groups, and adsorbed molecular water. Density functional theory calculations were used to aid in the interpretation of the APXPS results. An inherent lack of Lewis acid metal sites results in weak interactions of DMMP with MoO3. Adsorption is enhanced by the presence of oxygen vacancies, hydroxyl groups, and molecular water on the MoO3 surface, as measured by photoelectron spectroscopy. Computational results agree with these findings and suggest the