Deviations from perfect crystallinity often occur as local ordering phenomena that break the average symmetry at the nanoscale. A typical example are strongly correlated materials where charge, spin, orbital and lattice degrees of freedom result in competing interactions. These lead to phase transitions and the emergence of exotic nanophases promising a variety of novel functionalities and devices with enhanced performance. Another example are relaxors of the perovskite family exhibiting an exceptional electromechanical coupling and large dielectric constants that are desirable in many applications. The useful properties of relaxors are thought to arise from the existence of nanometer-sized ferroelectric domains that are embedded in a non-ferroelectric matrix and short-range ordering of different cations occupying crystallographically equivalent sites. Measuring nanoscale fluctuations with atomic resolution and correlating them with the macroscopic physics underlying the material behavior remains a challenge. We will employ high-energy resonant scattering coupled to element-specific atomic pair distribution function analysis to study the local atomic ordering in complex systems of the type described above. The effort also includes a methodological development of the technique.
|Effective start/end date||02/15/19 → 10/31/20|
- Basic Energy Sciences
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