Journal Article X-ray absorption diffuse scattering phase transitions synchrotron X-ray diffraction Li-ion batteries PMN-PT Research Support, Non-U.S. Gov't X-ray diffraction X-ray scattering area detector area detectors capillary heater cathodes chemical solution deposition computer programs data analysis and visualization data processing diffractometry energy storage epitaxial thin films ferroelectricity high-temperature thin-film environments in situ studies in situ two-dimensional X-ray single-crystal diffraction iron hydroxy fluorides metal halide perovskites metal-ion batteries operando electrochemical cells optoelectronic thin films