SuperSTEM: HAADF/EELS Investigation of Multifunctional Ceramics

Functional ceramics are important components in a wide range of domestic, leisure and industrial electronic systems. These include microwave dielectrics in mobile telephone systems, pressure sensitive materials used as detectors in control and positioning systems (for example cameras and automobiles), electrical protection devices in domestic and industrial environments, and novel materials which could be used in future device memory and energy generation systems. Improvement in these materials and the development of new materials depends critically on knowledge of the structure and chemistry of the materials at the atomic level. We will use the SuperSTEM electron microscope to investigate the structure and the position/distribution of individual dopant ions and vacancies in the lattice, in sub-grain features including twin boundaries, in anti-phase boundaries and domain boundaries, and the grain boundaries of functional ceramics including:microwave dielectrics, lead-free piezoelectrics, ceramics with grain boundary controlled properties, multiferroics and thermoelectrics .

The impact of this programme is maximised through collaborative links with electroceramics manufacturers and other research groups, both within the UK and overseas. At the end of the project we will have established a firm understanding of the atomic level microstructure in a range of commercially important functional ceramics and its role in controlling functional properties. The information will be valuable to manufacturing industry in the design of new and enhanced functional ceramics. Specific information and results from this project will be publicised and disseminated via: presentations at national and international conferences, our University website research pages, and Manchester University's Technology Transfer Company, UMIP. All the preliminary investigations of the functional ceramics itemised in the proposal submitted to the SuperSTEM have been undertaken in association with UK electroceramic manufacturers including Morgan Electroceramics and Powerwave Ltd, and international research groups (including National University of Singapore, National Institute for Materials Science Japan, University of Oulu Finland, and Tokyo Tech Japan). The work is directly relevant to industry because we have chosen to study systems that are currently under manufacture by UK companies, either within the UK or overseas, or are new systems being considered for future exploitation. The UK manufacturers will be kept fully informed of important findings with a view to appropriate exploitation. We will pursue a basic science project within the context of industry driven requirements for each system, allowing the knowledge gained to be applied directly to improving the quality of a wide range of electroceramics and increasing the competitiveness of UK industry in this area. The work on piezoelectric ceramics and PTCR thermistors focuses directly on lead-free systems, with a target of replacing the existing products which are used extensively worldwide and contain a significant fraction of lead. Both the lead-free piezoelectrics and PTCR thermistors show encouraging properties but the factors limiting the performance need to be identified and routes to enhanced properties defined. Introduction of the lead-free products will have social and environmental benefits for the whole of the UK, enhancing quality of life and health. Details of the results acquired will be disseminated to the scientific and manufacturing communities via conference presentations and established, high impact, refereed scientific publications. Key results of this work will be fed into research led, final year undergraduate and MSc courses and projects to provide awareness and training in this area. Use will also be made of our research group web pages to publicise developments. The researchers involved with the project will gain experience of internationally-leading characterisation techniques. The primary contact for exploitation of research findings will be via the University of Manchester Technology Transfer Company, UMIP. The applicant has over twenty years experience with electronic ceramics, including semiconducting, dielectric materials, piezoelectric and grain boundary controlled materials, particularly structure-property relationships. Work on microwave dielectrics and semiconducting ceramics has focused on processing, microstructure development and understanding loss mechanisms in such materials. Extensive use has been made of transmission electron microscopy to understand the role of domain-level and grain-boundary level processes.