Extracting interface correlations from the pair distribution function of composite materials

Using a non-negative matrix factorisation (NMF) approach, we show how the pair distribution function (PDF) of complex mixtures can be deconvolved into the contributions from the individual phase components and also the interface between phases. Our focus is on the model system Fe parallel to Fe3O4. We establish proof-of-concept using idealised PDF data generated from established theory-driven models of the Fe parallel to Fe3O4 interface. Using X-ray total scattering measurements for corroded Fe samples, and employing our newly-developed NMF analysis, we extract the experimental interface PDF ('iPDF') for this same system. We find excellent agreement between theory and experiment. The implications of our results in the broader context of interface characterisation for complex functional materials are discussed.

Automated summary

By using the non-negative matrix factorisation (NMF) approach, the study demonstrates how the pair distribution function (PDF) of complex mixtures can be separated into contributions from individual phase components and interfaces between phases, focusing specifically on a model system Fe parallel to Fe3O4. The experimental results show excellent agreement with theoretical predictions, highlighting the significance of this method in characterising interfaces in complex functional materials.