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Browsing Book Chapters by Author "Bak, T"

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    Defect engineering of photosensitive oxide materials. Example of TiO2 solid solutions
    (Elsevier, 2018) Atanacio, AJ; Bak, T; Rahman, KA; Nowotny, J
    The imperative to protect the environment from increasingly apparent climate change imposes the urgent need to reduce the emissions of greenhouse gases to the atmosphere. This, consequently, results in intensification of research in the development of new materials and devices for the generation of energy that is environmentally clean. This work considers photosensitive oxide semiconductors for solar energy conversion by light-induced water oxidation. It has been documented that the performance of oxide semiconductors for solar-to-chemical energy conversion is determined by a range of defect-related properties, including the concentration of surface active sites, Fermi level, charge transport, electronic structure, and alignment of band edges with the energy level of the redox couple. The present work considers the research strategy in processing TiO2-based semiconductors, which are the promising candidates for a new generation of solar materials. It is shown that the performance-related properties of TiO2 and its solid solutions are determined by surface versus bulk defect disorder and the associated semiconducting properties. Therefore, the development of TiO2-based materials with enhanced performance could be based on using defect engineering for imposing optimized bulk versus surface properties. In this work, we discuss a range of defect-related properties of TiO2 and its solid solutions, such as electrical and optical properties and the related photocatalytic performance. We show that the phenomenon of segregation may be used as the technology for imposition of controlled surface versus bulk defect disorder that is required for processing the systems with optimized properties. Copyright © 2018 Elsevier Inc.
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    Segregation-induced low-dimensional surface structures in oxide semiconductors
    (Springer-Verlag Berlin Heidelberg, 2014-03-01) Atanacio, AJ; Bak, T; Chu, D; Ionescu, M; Nowotny, J
    The present work considers quasi-isolated low-dimensional surface structures, which are formed as a result of segregation of intrinsic and extrinsic defects in oxide semiconductors. It has been documented that the local properties of these structures, such as crystalline structure, electronic structure, chemical composition, as well as charge and mass transport kinetics, are entirely different from those of the bulk phase. There is an increasingly urgent need to better understand their local properties, which have a strong impact on the reactivity of solids in general and photocatalytic properties in particular. The accumulation of data on the properties of surface structures opens a new discipline of the science of materials interfaces. The present work is focused on the surface structures, which are formed at TiO2-based semiconductors. It is shown that these structures play crucial role in the conversion of solar energy into chemical energy. © 2014, Springer-Verlag Berlin Heidelberg.