Dielectrics and Conductors

The functionality of dielectrics and conductors most frequently lies in some form of molecular or ionic disorder. Accordingly, if we are to become able to tailor materials to suit a specific dielectric or (super)conducting application, we need to understand this disorder at the atomic and molecular level.

The most revealing of materials characterization approaches to quantify ionic or molecular disorder is X-ray or neutron diffraction. Specifically, a wealth of structural information can be drawn from the diffuse scattering features that surround Bragg positions in a crystal structure, in cases where disorder is prevalent. By capturing this information, we can start considering molecular design principles that will enable the molecular engineering of more advanced dielectric and conducting materials.

By way of a few examples, we have previously sought to unravel the nature of the disorder in chlorobenzene derivatives, which is responsible for their anomalous dielectric properties. We are currently investigating diffuse scattering signatures in a new class of superconductors (iron arsenides).

Selected publications

Calculated (top) and observed (bottom) diffuse scattering patterns for pentachloronitrobenzene; the hk0 plane is shown.