Crystal growth of functional and multi-functional oxides

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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.