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Title: Local crystal structure of Bi-based perovskites solved by RMC modeling
Author: Szczecinski, Robert
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2013
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The local structure investigation by Reverse Monte Carlo modeling and comparison to average crystallographic structure of Bi-based perovskite materials are presented in this thesis. This novel technique using neutron total scattering is applied in search of possible short-range correlations between atoms to understand complex structure of these materials. Chapter One gives an introduction into perovskite structure and its properties. Chapter Two describes the difference between periodic and aperiodic crystals, which average crystallographic structure has been adopted by materials presented in this thesis. It also describes the total scattering and Pair Distribution Functions used in Reverse Monte Carlo modeling. The next chapters describe the local and average structure investigated during this thesis. Chapter Three describes the local and average perovskite structure of BiTi3/8Fe1/4Mg3/8O3 at various temperatures, where local structure analysis revealed particular displacements and correlations of A site and B site cations not captured by average crystallographic structure. Chapter Four compares local structure derived from RMC modeling and average incommensurate and commensurate crystallographic structures of Bi2Mn4/3Ni2/3O6 at room and high temperatures respectively, demonstrating importance of recognizing the length-scale of the probe used for structural characterization. Chapter Five describes the work on BiFe0.6Mn0.4O3 perovskite which was investigated by traditional crystallography to determine the modulated behavior and distorted structure of this material. The last Chapter 6 contains main conclusions from all experimental chapters.
Supervisor: Rosseinsky, Matthew J.; Claridge, John B. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: QD Chemistry