Episode 19: 4D-STEM measures thermal properties of 2D materials

In this podcast episode, MRS Bulletin’s Laura Leay interviews Michael Pettes, deputy group leader and staff scientist at the Center for Integrated Nanotechnologies in Los Alamos National laboratory about a characterization technique that employs a four-dimensional scanning transmission electron microscope (4D-STEM) paired with complex computational data analysis to directly measure the thermal expansion coefficient (TEC) of monolayer epitaxial tungsten diselenide. The standard technique for directly measuring the TEC involves X-ray diffraction, but 2D materials are too thin. 4D-STEM uses a patterned electron probe which enables diffraction positions to be accurately mapped in real space. This method overcomes the challenges of indirect measurements and spatial resolution. This work was published in a recent issue of ACS Nano (https://pubs.acs.org/doi/10.1021/acsn...) .