Advanced Characterization of Materials using Electron/Ion Microscopy

McDonnell Douglas Engineering Auditorium

ChEMS Seminar

Dr. Meng Gu

Materials researcher, Pacific Northwest National Laboratory (PNNL)

The advances in the aberration-corrected scanning / transmission electron microscopy have enabled the study of physical structure, chemical composition, bonding of complicated chemical substance at the atomic scale and in three dimensions. In this talk, I will demonstrate the critical role that electron microscopy plays in the study of complex interfaces in thin films, battery materials and catalysis. Firstly, I will give an introduction on the modern analytical electron microscopy technology, sample preparation methods, and various signals that can be collected from an electron microscope. The finding of the driving mechanism for forming a perfect Ohmic contact between Cr metal and Nb-SrTiO3 semiconductor will be introduced as an example of the atomic scale scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) technology. In addition, three-dimensional x-ray energy dispersive spectroscopy tomography was developed during my study of Li1.2Ni0.2Mn0.6O2 cathode materials and used to accurately locate and quantitatively analyze the Ni-segregated regions in one single nanoparticle. Furthermore, I will introduce the development of in-situ and operando study of silicon nanostructures in the open/closed cell battery in the electron microscope. Last but not least, a few examples will be given to show that He-ion microscopy offers the advantage of higher resolution, no-charging effect, and more surface-sensitivity on the study of batteries and catalysis samples. A combination of STEM and He-ion microscopy can resolve critical issues in the field of materials science.  



Dr. Meng Gu is a materials researcher in the Environmental Molecular Sciences Laboratory (EMSL) in Pacific Northwest National Laboratory (PNNL). He received B.S. degree (2008) in materials science and engineering in Shanghai Jiao Tong University in China and Ph.D. degree (2011) in materials science in the University of California Davis. His Ph.D. research centered on the growth and atomic scale characterization of complex oxide thin films using pulsed laser deposition and aberration corrected scanning transmission electron microscopy (STEM). After joining EMSL PNNL, his research shifted to the study of energy-related materials including batteries materials, and catalysis, metal-oxide electronics.