Martin Mallinson, Phillip
(2007)
Perovskite Microwave Dielectric Ceramics: Structure, Properties and Processing.
PhD thesis, University of Liverpool.
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Abstract
Perovskite Microwave Dielectric Ceralnics: Structure, Properties and Processing PhD thesis, Phillip M. Mallinson, University of Liverpool This thesis describes the synthesis and characterisation of several new hexagonal perovskite materials and the investigation into the processing of a commercial microwave dielectric. Chapter 1 is in two parts, the first gives an introduction to the perovskite and hexagonal perovskite structural types, and reviews the structure and properties of reported hexagonal perovskites with the AnBn-\03n general formula. The second part reviews the literature on the microwave dielectric material Ba3ZnTa209 (BZT). In Chapter 2 the details of the synthetic and analytical techniques employed are described. Chapter 3 describes the synthesis and characterisation of a number of new hexagonal perovskite materials. The eight layer compounds BagCoNb60 24 and BagCoTa6024 were found to crystallise with different structures in the space groups P 3ml and P63c11l respectively. A detailed structural description and comparison of the structures of the materials is given along with the dielectric and magnetic properties. The structure and dielectric properties of the six layer material Ba6Ca1l3Nb\4/30\g are also presented. Chapter 4 describes the synthesis and characterisation of two isostructural ten layer hexagonal perovskites with the formulas BalOMgo.25Ta7.903o and BaIOCoO.25Ta7.903o. Refinement of combined synchrotron X-ray and neutron powder diffraction data is used to determine the structures of the materials. The dielectric properties of the materials are reported and the links between dielectric loss and ordering and microstructure discussed. In Chapter 5 the results of an in-situ X-ray powder diffraction study of the ordering and domain growth ofBZT at temperatures between 1200 and 1500 °C is presented. The degree of ordering is quantified using two different methods and a rate of ordering calculated at each of the temperatures studied, from the rates of ordering the activation energy for cation transport is calculated. The ordered domain size is also quantified from the diffraction data and the dynamics compared to domain growth in other systems. Supplied by The British Library - 'The world's knowledge'
| Item Type: | Thesis (PhD) |
|---|---|
| Depositing User: | Symplectic Admin |
| Date Deposited: | 20 Oct 2023 09:24 |
| Last Modified: | 20 Oct 2023 09:41 |
| DOI: | 10.17638/03174456 |
| Copyright Statement: | Copyright © and Moral Rights for this thesis and any accompanying data (where applicable) are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3174456 |
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