  Structure-property relationships in ordered materials have long been a core
principle in materials design. However, the intentional introduction of
disorder into materials provides structural flexibility and thus access to
material properties that are not attainable in conventional, ordered materials.
To understand disorder-property relationships, the disorder - i.e., the local
ordering principles - must be quantified. Correlated disorder can be probed
experimentally by diffuse scattering. The analysis is notoriously difficult,
especially if only powder samples are available. Here, we combine the
advantages of three-dimensional electron diffraction - a method that allows
single crystal diffraction measurements on sub-micron sized crystals - and
three-dimensional difference pair distribution function analysis
(3D-{\Delta}PDF) to address this problem. 3D-{\Delta}PDFs visualise and
quantify local deviations from the average structure and enable a
straightforward interpretation of the single crystal diffuse scattering data in
terms of a three-dimensional local order model. Comparison of the
3D-{\Delta}PDF from electron diffraction data with those obtained from neutron
and x-ray experiments of yttria-stabilized zirconia demonstrates the
reliability of the newly proposed approach.
