title: Fast Atomic-Scale Chemical Imaging of Crystalline Materials and Dynamic Phase Transformations.
abstract: Atomic-scale phenomena fundamentally influence materials form and function that makes the ability to locally probe and study these processes critical to advancing our understanding and development of materials. Atomic-scale chemical imaging by scanning transmission electron microscopy (STEM) using energy-dispersive X-ray spectroscopy (EDS) is a powerful approach to investigate solid crystal structures. Inefficient X-ray emission and collection, however, require long acquisition times (typically hundreds of seconds), making the technique incompatible with electron-beam sensitive materials and study of dynamic material phenomena. Here we describe an atomic-scale STEM-EDS chemical imaging technique that decreases the acquisition time to as little as one second, a reduction of more than 100 times. We demonstrate this new approach using LaAlO3 single crystal and study dynamic phase transformation in beam-sensitive Li[Li0.2Ni0.2Mn0.6]O2 (LNMO) lithium ion battery cathode material. By capturing a series of time-lapsed chemical maps, we show for the first time clear atomic-scale evidence of preferred Ni-mobility in LNMO transformation, revealing new kinetic mechanisms. These examples highlight the potential of this approach toward temporal, atomic-scale mapping of crystal structure and chemistry for investigating dynamic material phenomena.
authors.affiliation: Sandia National Laboratories , Albuquerque, New Mexico 87185, United States.
authors.forename: Ping
authors.initials: P
authors.lastname: Lu
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , 1304 W. Green Street, Urbana, Illinois 61801, United States.
authors.forename: Ren Liang
authors.initials: RL
authors.lastname: Yuan
authors.affiliation: Sandia National Laboratories , Albuquerque, New Mexico 87185, United States.
authors.forename: Jon F
authors.initials: JF
authors.lastname: Ihlefeld
authors.affiliation: Sandia National Laboratories , Albuquerque, New Mexico 87185, United States.
authors.forename: Erik David
authors.initials: ED
authors.lastname: Spoerke
authors.affiliation: Sandia National Laboratories , Albuquerque, New Mexico 87185, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Pan
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , 1304 W. Green Street, Urbana, Illinois 61801, United States.
authors.forename: Jian Min
authors.initials: JM
authors.lastname: Zuo
keywords: STEM-EDS; Time-resolved; atomic-scale; dynamic; lattice-vector translation; phase transformation