Current Inorganic Chemistry (v.3, #1)
Preface by Yann GARCIA (i-i).
Editorial (Hot Topic: Advanced Complex Oxides) by Paolo Ghigna (1-1).
Comprehensive Review of Current Developments in IT-SOFCs by Daniel Marinha, Laurent Dessemond, Elisabeth Djurado (2-22).
Solid oxide fuel cell (SOFC) systems provide an alternative electricity production source, with potentially zero carbon emissions. In order to decrease the chemical and mechanical degradation in its components, operation temperature of SOFCs must be lowered. However, transport phenomena required for SOFC adequate operation are temperaturedependent. Therefore, new materials must be devised to compensate for the temperature decrease. This paper reviews the state-of-the art on SOFCs devices and materials intended for operation below 700 °C, named intermediate temperature (IT)-SOFCs. Current research developments on electrolyte, cathode and anode materials are reviewed. Emphasis on the critical issues of cathode/electrolyte half-cell is made. The relatively recent LSCF/CGO system has shown promising polarization resistance behavior, reaching 0.13 Ω.cm2 at 600 °C, and is often contrasted to the conventional LSM/YSZ combination. The oxygen reduction reaction mechanism and interconnect materials are also reviewed. Electrostatic spray deposition is highlighted as a promising film deposition technique, able to produce a large variety of oxide film microstructures by controlling a few deposition parameters. One of the advantages is the ability to obtain large surface area films due to the arrangement of nano-sized solid particles.
Oxide - Oxide Reactions in the Solid State by Giorgio Spinolo, Ilenia G. Tredici, Sonia Pin (23-34).
The work overviews the reactivity between solid oxides from the fundamental thermodynamic aspects to the diffusion controlled growth of the reaction product, to the reactions at interfaces and the role of surface energy. The final part reports some recent mechanistic achievements concerning the nucleation at the very early stage of a solid-solid reaction.
Disorder in Oxides by Marco Scavini, Mauro Coduri (35-49).
In this paper the intimate correlation among structure, defect thermodynamics and physical properties in oxides is briefly reviewed through few examples concerning high Tc superconductors and ionic conductors. In some cases the desired physical properties appear only when disorder is introduced in the structures, like in neodymium cuprate and doped ceria. Disorder can be even expressly introduced in order to tune the physical properties already present in the undoped compound, which is the case of Al-doped REBa2Cu3O6+δ. It will be demonstrated that not only the point defects and the local distortions induced by them, but also the correlation lengths of disorder are to be taken into account in order to correctly understand the physical properties of interesting materials.
Advanced Oxides In Catalysis by Ilenia Rossetti (50-69).
Oxides, either simple or mixed, play a key role in catalysis, as active phase or supports. Tuning the catalytic properties is possible by changing the formulation, by doping or by selecting appropriate structure and morphology. Of course adequate preparation procedures should be optimized to achieve these goals. Examples are taken from the field of photocatalysis mediated by TiO2, which offers the opportunity to check the effect of all the above reported parameters on the catalytic behavior. Furthermore, mixed oxides of various formulations are described, with widely different applications.
Multiferroic Properties In Complex Oxides by Claudio Mazzoli, Paolo Ghigna (70-74).
Often papers dealing with multiferroics (MFs) begin by defining the complex group of materials they deal with. This compelling need highlights the complexity of the issue and the importance of a common language, in consideration of the various communities involved. Our article follows a bottom-up approach by introducing the playground of electrons in matter, their susceptibilities and possible spontaneous orders in simple cases. Then, multiferroic properties are recalled, together with a number of examples. Special attention is focused on the magnetoelectric interaction. The fundamental role of oxides in the field is pointed out in terms of number, importance and perspective offered in the panorama of desired applications. A historical overview accompanies the development of concepts, definitions and discoveries. Current challenges and new perspectives are presented.