A3B2B'O9 perovskites; making use of cation disorder to synthesize new magnets

Solids are very complex materials. They contain millions of atoms, each of which interacts with those immediately around it and, sometimes, with those somewhat further away. Each atom usually has between four and twelve neighbours, and of course they all have other neighbours so the complexity of the interactions increases rapidly as you move out from your starting point. If the atoms are arranged regularly in space, then the solid is said to be crystalline and it is easier to deal with these than those where the atoms are not periodically arranged, known as amorphous materials.
Even in a crystalline solid it is difficult to understand what interactions are taking place. Sometimes there are sites in a crystal that we know are occupied by an atom, but we cannot be sure what type of atom it will be. That is, the atom at a particular point could be either of two different chemical elements. If we know what type of element is at every site in the crystal, then the compound is said to be structurally ordered; if we cannot be sure, then it is said to be disordered. If the crystal is structurally ordered, then it is relatively straightforward to predict what properties the crystal might have, although the number of interactions in which it takes part is still so large that it is rarely trivial to do so accurately. If the compound is structurally disordered then it is very difficult to predict what will happen because there the environment of every atom is somewhat random in nature. Often the presence of disorder prevents the compound having useful properties, for example being a good electrical conductor or a strong magnet. The challenge facing chemists is to turn the tables on nature and make new compounds whose natural disorder is responsible and essential for endowing the compound with useful properties. The research described in this proposal aims to show that oxides containing lanthanum, nickel and antimony show useful magnetic properties only because of the fact that some of the magnetic atoms (nickel) are mixed up with antimony on one set of sites in the structure.

The research described in this proposal is fundamental solid-state chemistry, although it lies close to the border with solid-state physics and could be regarded as multi-disciplinary. The aim is to synthesize a range of compounds and identify the factors that cause some of them to behave as 'relaxor ferromagnets", i.e. to show a large magnetisation once exposed to a magnetic field but none before the field is applied. The work is thus a long way from "materials science", which is essentially about taking a known compound with established properties and processing it in some way that allows it to be used as a device. Thus the work will enhance the knowledge economy, and I expect it to be regarded as internationally competitive. The project will provide good training for post-graduate students.
The work has the potential to improve quality of life if a compound is found that, with suitable processing, can be developed into a useful magnetic material. However, this development could not begin until the proposed research is complete. If such a material can eventually be developed it would contribute to wealth creation and economic prosperity and could attract R&D investment from global business. This might involve the formation of a spin-out company to develop new products. Those who work on the project would gain skills and expertise that would be useful in non-academic professions.