Advanced Electroceramic Materials: Structural Origins of Properties

Igor Levin (Materials Measurement Science Division, NIST)

Atoms in crystals form symmetric arrays determined by the interplay between interatomic forces. In many cases, symmetry depends on the lengthscale, yielding distinct atomic arrangements (structure) over local (sub-nm to several nm) and macroscopic scales. Differences between the local and average (macroscopic) structures, even subtle ones, often control the exploitable properties (dielectric, thermoelectric, magnetic,etc.) of advanced materials. Therefore, determination of the local atomic arrangements is key to establishing structure-property relations for the design of new materials. Today, various measurement techniques exist for probing local atomic order. Nonetheless, finding accurate comprehensive structural solutions remains a challenge because any one of the existing methods yields only a partial view of the structure. In this talk, we will discuss recent advances in local-structure determination in polycrystalline materials using simultaneous fitting of neutron total scattering, X-ray absorption fine structure, and electron diffuse scattering data. The multiple-technique approach enables explicit determination of instantaneous atomic positions with accuracy and detail inaccessible by single-technique analyses. We will use representative electroceramic systems as examples to illustrate how detailed knowledge of the local structure can elucidate the origin of functional properties.

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