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Revealing whether dislocations accelerate oxygen ion transport is important for providing abilities in tuning the ionic conductivity of ceramic materials. In this study, we report how dislocations affect oxygen ion diffusion in Sr-doped LaMnO3 (LSM), a model perovskite oxide that serves in energy conversion technologies. LSM epitaxial thin films with thicknesses ranging from 10 nm to more than 100 nm were prepared by pulsed laser deposition on single-crystal LaAlO3 and SrTiO3 substrates. The lattice mismatch between the film and substrates induces compressive or tensile in-plane strain in the LSM layers. This lattice strain is partially reduced by dislocations, especially in the LSM films on LaAlO3. Oxygen isotope exchange measured by secondary ion mass spectrometry revealed the existence of at least two very different diffusion coefficients in the LSM films on LaAlO3. The diffusion profiles can be quantitatively explained by the existence of fast oxygen ion diffusion along threading dislocations that is faster by up to 3 orders of magnitude compared to that in LSM bulk.

Isotope exchange depth profiling and electrochemical impedance spectroscopy are usually regarded as complementary tools for measuring the surface oxygen exchange activity of mixed conducting oxides, for example used in solid oxide fuel cell (SOFC) electrodes. Only very few studies compared electrical (k(q)) and tracer (k*) exchange coefficients of solid-gas interfaces measured under identical conditions. The 1:1 correlation between k(q) and k* often made is thus more an assumption than experimentally verified. In this study it is shown that the measured rates of electrical and tracer exchange of oxygen may strongly differ. Simultaneous acquisition of k(q) and k* on La0.6Sr0.4FeO3-δ and SrTi0.3Fe0.7O3-δ thin film electrodes revealed that k*100 k(q) in humid oxidizing ((16)O2 + H2(18)O) and humid reducing (H2 + H2(18)O) atmospheres. These results are explained by fast water adsorption and dissociation on surface oxygen vacancies, forming two surface hydroxyl groups. Hence, interpreting experimentally determined k* values in terms of electrochemically relevant oxygen exchange is not straightforward.

International audience; We employed operando anomalous surface X-ray diffraction to investigate the buried interface between the cathode and the electrolyte of a model solid oxide fuel cell with atomic resolution. The cell was studied under different oxygen pressures at elevated temperatures and polarizations by external potential control. Making use of anomalous X-ray diffraction effects at the Y and Zr K-edges allowed us to resolve the interfacial structure and chemical composition of a (100)-oriented, 9.5 mol % yttria-stabilized zirconia (YSZ) single crystal electrolyte below a La0.6Sr0.4CoO3-delta (LSC) electrode. We observe yttrium segregation toward the YSZ/LSC electrolyte/electrode interface under reducing conditions. Under oxidizing conditions, the interface becomes Y depleted. The yttrium segregation is corroborated by an enhanced outward relaxation of the YSZ interfacial metal ion as layer. At the same time, an increase in point defect concentration in the electrolyte at the interface was observed, as evidenced by reduced YSZ crystallographic site occupancies for the cations as well as the oxygen ions. Such changes in composition are expected to strongly influence the oxygen ion transport through this interface which plays an important role for the performance of solid oxide fuel cells. The structure of the interface is compared to the bare YSZ(100) surface structure near the microelectrode under identical conditions and to the structure of the YSZ(100) surface prepared under ultrahigh vacuum conditions

Many efforts are being made to tune perovskite thin film cathodes toward improving their oxygen reduction kinetics and thereby improving overall solid oxide fuel cell performance. One approach is to enhance oxygen diffusion via introduction of larger concentrations of grain boundaries during thin film growth. While such grain boundary engineering has been shown to enhance ionic transport and surface reaction kinetics in some cases, little attention has been paid on its corresponding influence on electronic conductivity. To provide insights into the role of grain boundaries and their contribution to the cathode performance, we have investigated separately the electronic and ionic conductivity of La0.8Sr0.2MnO3(LSM) thin films by Van-der-Pauw and18O tracer exchange measurements respectively, as well as their combined contributions by electrochemical impedance spectroscopy. All three types of experiments were performed on the same kind of samples with varying LSM microstructure to illustrate the effects of grain boundaries on both electron and ion conduction. Correlations between active electrode area and microstructure-dependent partial conductivities are presented. The findings can also be used for optimizing current collector spacing in thin film solid oxide fuel cells. Keywords: grain boundary engineering; LSM; thin film, United States. Department of Energy (Grant DE-SC0002633)

Protection of Public Interest in Civil Procedure Protection of public interest is the procedure which safeguards the most significant public value. Even though there might be an impression that this doctrine has been widely discussed and as a result it may lack scientific sensitivity, the author does not agree with that. The significance and characteristics of public interest are challenges themselves and as a consequence, they determine the importance of continuous investigation in the field of public interest. Legal regulation changes, inconsistency of judicial practice and lack of systematic analysis of specific doctrines are of great importance for this investigation and reveal a wide range of research problems. However, the most important aspect of this research is that the author does not limit himself only to the field of the usual public interest research (for example, the doctrine of public interest or the concept of public interest). On the contrary, the author chooses new directions meanwhile paying attention to the important issues that previously have not been analysed. As a result, the problem of justifying the efficiency, the prosecutor's supervisory role and the legal basis of the state and municipalities are the areas that demonstrate the uniqueness of this very research. On the other hand, the researcher is not only a passive observer. After analysing scientific positions, the author looks for new arguments in order to deny or support the theories and discuss and justify his own position. Finally, the researcher comes to the conclusions that allow one to decide on: 1) the prevailing concept of the shared values in Lithuania and the possible duality of the concepts; 2) the criterion on the justification of the public interest; 3) the approval of prosecutor´s supervisory role; 4) the duties of the state and municipalities; 5) the groundlessness of the court, as an entity, protecting the public interest; and other aspects important for the protection of public interest in civil proceedings.

The different properties of acceptor-doped (hard) and donor-doped (soft) lead zirconate titanate (PZT) ceramics are often attributed to different amounts of oxygen vacancies introduced by the dopant. Acceptor doping is believed to cause high oxygen vacancy concentrations, while donors are expected to strongly suppress their amount. In this study, La3+ donor-doped, Fe3+ acceptor-doped and La3+/Fe3+-co-doped PZT samples were investigated by oxygen tracer exchange and electrochemical impedance spectroscopy in order to analyse the effect of doping on oxygen vacancy concentrations. Relative changes in the tracer diffusion coefficients for different doping and quantitative relations between defect concentrations allowed estimates of oxygen vacancy concentrations. Donor doping does not completely suppress the formation of oxygen vacancies; rather, it concentrates them in the grain boundary region. Acceptor doping enhances the amount of oxygen vacancies but estimates suggest that bulk concentrations are still in the ppm range, even for 1% acceptor doping. Trapped holes might thus considerably contribute to the charge balancing of the acceptor dopants. This could also be of relevance in understanding the properties of hard and soft PZT.

In this study, the contribution of grain boundaries to the oxygen reduction and diffusion kinetics of La[subscript 0.8]Sr[subscript 0.2]MnO[subscript 3] (LSM) thin films is investigated. Polycrystalline LSM thin films with columnar grains of different grain sizes as well as epitaxial thin films were prepared by pulsed laser deposition. 18O tracer exchange experiments were performed at temperatures from 570 °C to 810 °C and subsequently analyzed by secondary ion mass spectrometry (SIMS). The isotope concentration depth profiles of polycrystalline films clearly indicate contributions from diffusion and surface exchange in grains as well as in grain boundaries. Measured depth profiles were analyzed by finite element modeling and revealed the diffusion coefficients D and oxygen exchange coefficients k of both the grain bulk and grain boundaries. Values obtained for grain boundaries (D[subscript gb] and k[subscript gb]) are almost three orders of magnitude higher than those of the grains (D[subscript g] and k[subscript g]). Hence, grain boundaries may not only facilitate fast oxygen diffusion but also fast oxygen exchange kinetics. Variation of the A-site stoichiometry ((La[subscript 0.8]Sr[subscript 0.2])0.95MnO[subscript 3]) did not lead to large changes of the kinetic parameters. Properties found for epitaxial layers without grain boundaries (Db and kb) are close to those of the grains in polycrystalline layers., Austrian Science Fund (FWF project F4509-N16), Austrian Science Fund (FWF project P21960-N17), Austrian Science Fund (FWF project W1243-N16), United States. Dept. of Energy. Office of Basic Energy Sciences (Grant No. DE-SC000263)