Soft chemical control to achieve new layered architectures and strongly correlated states.

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Solid state chemistry involves the synthesis of (normally) crystalline solids (compounds resembling minerals) and optimisation of their compositions so as to realise particular physical or chemical properties, such as conductivity or magnetism. Often these compounds are synthesised at high temperatures so that the ionic mobility is high enough for the reactions to proceed. Under this thermodynamic control of the synthesis the range of compositions available for a particular combination of elements may be limited. So complementary low temperature (e.g. at room temperature, or even below) syntheses are another way of changing the chemical composition and this may enable a wider range of chemical compositions to be attained. The low temperature chemistry, normally an intercalation or a deintercalation, is possible if the compound supports high mobility of some of its constituent ions. The work proposed here starts from the demonstration that deintercalation chemistry of a series of layered transition metal compounds is possible and does have profound effects on the electronic properties. The targets are compounds where compositional tuning may be carried out continuously and over a wide compositional range. The transition metals in these compounds and the two-dimensional crystal structures have been chosen so as to yield strongly-correlated-electron systems where the electronic behaviour is not easy to predict due to several competing factors, and where unusual electronic phenomena, such as superconductivity, magnetoresistance, high thermoelectric power and metal-to-insulator transitions are often found. In addition to producing new compositions, we will explore ways in which the chemistry can be applied to large crystals of the compounds in order to give better insight into their microscopic properties.