Crystal growth of functional and multi-functional oxides

Concern over climate change, the environment and energy efficiency, has focused attention on the search for materials with new or better functionality. Functional materials have physical and chemical properties which change in response to external stimuli, such as electric and magnetic fields, temperature, pressure, exposure to light, or adsorption of atoms and molecules. Important examples of functional materials are thermoelectrics, ferroelectrics, multiferroics, magnetic field sensors, piezoelectric materials, fast-ion conductors, and superconductors. The design of better functional materials requires an understanding of how they work. To uncover their secrets, we need to perform experiments on single crystals with a high degree of purity and crystalline perfection. Samples in the form of single crystals are needed because most functional materials are crystalline and their properties vary with direction in the crystal.In this project I will grow single crystals of selected thermoelectric, magnetoelectric and superconducting materials then, through collaboration with experts in various experimental techniques, experimental investigations will be performed in order to uncover the properties of these materials and to provide data to test models for their behaviour.The materials I will concentrate are all oxides whose properties are driven by interactions between the electrons. They divide into 3 classes according to their function:(1) thermoelectrics - materials whose properties allow them to convert waste heat into energy or to use electricity directly for cooling and heating,(2) magnetoelectrics - materials which permit control of magnetism by electric fields and vice versa,(3) superconductors - materials which can conduct electricity without resistance.The growth of high quality bulk single crystals of complex materials is an advanced research activity requiring special techniques and equipment. I will use a method called the floating-zone method in a mirror furnace which uses light as the heat source. By experimenting with the growth conditions I hope to be able to grow crystals of very high quality which can be used by my collaborators in experiments to probe the mechanisms behind their physical properties.

The main direct beneficiaries of the work will be the members of the academic research community who require high quality single crystal samples for their research. Other immediate beneficiaries will be neutron, photon and muon facilities such as those at the Harwell Science and Innovation Complex. By providing a supply of samples for research at HSIC and other research institutes my work will contribute towards the successful exploitation of UK-funded central facilities and associated science and innovation centres. In the medium term I anticipate that there will be benefits in industrial sectors such as electronics, energy and information technology. These areas benefit because the work forms a part of the process by which functional materials are understood and developed. This project will contribute towards the training of young scientists in materials growth and characterization techniques. Graduate students, postdocs and Career Acceleration Fellows interested in using my crystals in their experiments will learn about the processes involved in optimizing and improving the quality of single crystals. Finally, the work will make a cultural contribution to society by providing fundamental insights into the nature of condensed matter. The quest for knowledge is an important part of our culture. The wide appeal of scientific discoveries, especially among young people, encourages intellectual curiosity, innovation and experimentation, and by doing so enhances the quality of life.To ensure that potential users are informed of my work I will publish results in peer-reviewed journals with the highest visibility and I will present the work at national and international conferences. News and information will also be spread using more rapid methods of dissemination (pre-print servers, departmental and inter-departmental research seminars). Results will also be posted in an easily-accessible format for non-specialists on group, departmental and university websites. If significant breakthroughs are made then I will work with the Oxford University Press Office to prepare press releases and ensure publicity through the media.My project will not attempt to make commercial devices, but where appropriate, new materials displaying properties suitable for application will be protected by patents drawn up by ISIS Innovation Ltd., Oxford University's intellectual property company.