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National Repository of Grey Literature 3 records found  Search took 0.01 seconds. 
First-principles studies of the electronic and structural properties of Lead Zirconate Titanate (PZT)
 Planer, Jakub ; Friák, Martin (referee) ; Bartošík, Miroslav (advisor)
This work is focused on Density Functional Theory (DFT) calculations of oxygen vacancy diffusion barriers in mixed perovskite lead zirconate titanate and its pure counterparts. We found out that barrier heights are different in lead titanate and lead zirconate caused by the different localization of the excess electrons due to the oxygen vacancy formation. Diffusion barriers were also determined for titanium-rich mixed phases and compared to experimental values. This work contributes to clarify unusually low experimentally measured diffusion coefficients in PZT. We found out that the induced vacancy states are forming localized bonds to the lead atoms which causes the oxygen vacancies to become immobile due to the increase of the activation energy of the diffusion process.
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Electronic and structural properties of model catalysts based on cerium oxide
 Duchoň, Tomáš ; Veltruská, Kateřina (advisor) ; Bartoš, Igor (referee) ; Kullgren, Jolla (referee)
Catalysts based on cerium oxide are ubiquitous in industrial-scale chemical conversion. Here, a thorough study of their fundamental properties is undertaken via a model system ap- proach with the goal of furthering rational design in heterogeneous catalysis. A focus is put on understanding the behavior of oxygen vacancies in cerium oxide with respect to atomic co-ordination and electronic structure perturbations. Utilizing state-of-the-art probing tech- niques, a scalable model system framework is developed that allows for control over both the oxygen vacancy concentration and local co-ordination. High precision of the innova- tive approach facilitated observation of new phases of substoichiometric cerium oxide and lead to a first-of-a-kind investigation of the electronic structure of cerium oxide throughout isostructural transition from CeO2 to Ce2O3. The acquired results advance fundamental understanding of essential properties of cerium oxide that are relevant to its utilization in heterogeneous catalysis and open new pathways for functionalization of cerium oxide-based materials. Furthermore, the methodology developed in the thesis is transferable to other important reducible oxides. 1
Detailed record
First-principles studies of the electronic and structural properties of Lead Zirconate Titanate (PZT)
 Planer, Jakub ; Friák, Martin (referee) ; Bartošík, Miroslav (advisor)
This work is focused on Density Functional Theory (DFT) calculations of oxygen vacancy diffusion barriers in mixed perovskite lead zirconate titanate and its pure counterparts. We found out that barrier heights are different in lead titanate and lead zirconate caused by the different localization of the excess electrons due to the oxygen vacancy formation. Diffusion barriers were also determined for titanium-rich mixed phases and compared to experimental values. This work contributes to clarify unusually low experimentally measured diffusion coefficients in PZT. We found out that the induced vacancy states are forming localized bonds to the lead atoms which causes the oxygen vacancies to become immobile due to the increase of the activation energy of the diffusion process.
Detailed record

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