Our aim is to use total neutron scattering to determine pair distribution functions that will allow us to examine the atomic-scale structure of some new mixed-metal carbide-nitride materials. The materials are prepared using a milder route than conventional methods and they are being investigated in catalysis. We require detail atomic-scale structural models to understand how their synthesis might be tuned to make materials with desirable properties. Neutrons provide a unique approach to this problem since the scattering lengths of the elements will provide good contrast compared to X-rays to provide high resolution pair distribution functions that will allow us to examine distortions from the average crystal structure and local (in)homogeneity.