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Electronic and Ionic Transport in Functional Oxides

Final Report Summary - ELIOT (Electronic and Ionic Transport in Functional Oxides)

Two of the main drivers of worldwide economic growth and scientific development are the semiconductor/IC industry and the need for new energy resources. The need for alternate renewable sources of energy such as sunlight and wind power, which are inherently discontinuous, poses new challenges for energy transport and storage. Although many of the materials used in the IC industry and in energy storage are similar, the research in their properties has been separated in two fields with very little interdisciplinary interaction. This proposal aims to cross this barrier and evaluate physical and electrical properties of transition metal oxides in their nanostructured form for memory and energy storage applications. We are investigating how material production and physical properties influence electronic and ionic transport in oxides.
Using materials where the resistive switching arises from correlated electron effects rather than oxygen or oxygen vacancy rearrangement, we investigate how material deposition technique and conditions influence electronic transport properties. A second objective here is if this switching can be induced by an external electric field. Focus here is on possible applications as switch/ memory elements.
The third objective is to study and evaluate Li transport in oxides. Some oxides are expected to show relatively high ionic mobility while being electron insulators making them interesting as solid electrolytes. Others oxides show high Li storage capacity and good electrical conductivity making them appropriate for electrode applications. Correlating Li transport properties with material production and electrical behavior can help better engineer materials for highly performing batteries.
We have investigated simple binary oxides such as vanadium or titanium oxides and expanded our investigation to more complex oxides such as SmNiO3 and LiMn2O4. Vanadium dioxide VO2 and SmNiO3 show a metal to insulator transition (MIT) with temperature. Titanium dioxide TiO2 and LiMn2O4 are promising electrode material for batteries, while LixMgyAl3-x-yO4 could be interesting as a solid electrolyte.
Our project focuses on fundamental understanding of transport mechanisms in transition metal oxides. However, the impact could be far reaching. We expect to further the understanding of how battery materials work which will potentially lead to the ability to design better materials. Producing better batteries has a large impact on society and economy, as batteries could facilitate the introduction of electric cars and reduction of green house emissions. Better batteries could also be used in portable electronics: the main performance limiter for these devices is the amount of energy and power that the battery can deliver.
Knowledge from the project could be used to build greener transistors, transistors that would use less energy. This gain would have a large socio-economic impact as it reduces the energy consumption needed to perform computationally intensive tasks. This could generate a new class of supercomputers that would allow breakthroughs in many fields, ranging from medicine discovery and drug design to industrial design and simulations. Greener transistors would also form the basis for environmentally friendly alternatives to the current power-hungry server farms.