Local structures of perovskite dielectrics and ferroelectrics via pair distribution function analyses

The pair distribution function (PDF) method provides a useful way of characterizing the diverse and richly complex local structures in perovskite dielectric and ferroelectric materials. This review provides a basic introduction to the PDF method and the underpinning total scattering experiments. Results are reviewed from ex situ PDF that describe composition-dependent local structures and "box-car" fitting approaches to characterize longer range structures and length-scale effects. In situ PDF studies are reviewed that are sensitive to the local structural response of perovskites to temperature, electric field, and pressure. The dynamic pair-density function is also briefly introduced as well as examples of local structure analysis using combined inputs, e.g., extended Xray absorption fine structure spectroscopy, Raman spectroscopy, and first-principle calculations. These advances in advanced and integrated analysis, dynamics, and in situ methods will enable the PDF method to continue enlightening dielectrics and ferroelectrics research in the coming decades.