Phonon Band Structure

Characterizing phonon band structure is key to understanding many material properties, from ferroelectricity to superconductivity.  One way to quantify this is by using X-ray and neutron diffuse scattering techniques, which has been indispensable for studying bulk materials.  Until recently, these techniques were inaccessible to electron microscopy as the EELS energy resolution was too poor and the diffraction cameras were insufficiently sensitive.  Overcoming the detection issue, the Electron Microscopy Pixel Array Detector (EMPAD)  can simultaneously capture both Bragg and diffuse scattering on a fully quantifiable scale.  This is enabling direct comparison between experiment and electron scattering theory. In comparison to X-ray and neutron scattering, the electron diffraction approach is simpler to set up, has shorter acquisition times, and less material restrictions. In combination, we are exploring the use of electron spectroscopy, diffuse scattering, and STEM image intensities as complementary tools to quantify local thermal transport.