Prof. Rong Huang [East China Normal University, China]

Title: Atomic Scale Visualization of Light Elements in Advanced Functional Oxide Materials

Time: 2:00 - 3:00 PM, Friday, November 20, 2015

Place: Conference Room 201, HPSTAR (Shanghai)

Host: Dr. Bin Chen

Abstract:

Light elements, such as Li and O, are the key component in many advanced materials like cathode materials for lithium ion battery and transition metal oxides for ferroelectric applications. Thus the local structures of light elements play a very important role on their physical properties and the electrochemical performance of lithium ion batteries. However, visualization of the light elements like Li and O are very difficult by electron microscopy because of their weak scatter capability to the electron beam.

With the development of spherical aberration corrector in the beginning of this century, scanning transmission electron microscope (STEM) equipped with an annular dark-field (ADF) detector and electron energy-loss spectrometer (EELS) becomes a very powerful tool to obtain useful structural and chemical information with atomic resolution. Very recently, annular bright-field (ABF) STEM imaging has been successfully used to image columns of both light and heavy elements simultaneously with good signal-to-noise ratio. This is a very promising technique because of its sensitivity to light elements and the robustness of the interpretation of direct images for a large range of sample thicknesses.

In this talk, we demonstrate some examples on the atomic-level imaging of light elements in various advanced oxide materials using the-state-of-the-art Cs-corrected STEM techniques:

(1) Direct observation of Li ions in LiMn2O4 and LiCoO2 cathode materials in real-space and real-time by using the ABF-STEM imaging technique.

(2) The preferential site occupancy of Mn in γ–Ga2O3 and the dedicate control of Mn valency.

(3) The Polarization pinning and relaxation at coherent BiFeO3/LaAlO3 interfaces.

Biography of the Speaker:

Prof. Rong Huang is a professor of the Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University (ECNU). He is also a guest researcher of the Japan Fine Ceramics Center (JFCC).



Prof. Huang received the B.S. degree in materials science and engineering from the Chongqing University, Chongqing, China in 1999, and the Ph.D. degree in materials physics and chemistry from the Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai, China, in 2005. He was a Postdoctoral Researcher in Kyoto University from April 2005 to March 2007 and at the Japan Fine Ceramics Center from April 2007 to March 2009. Since April 2009, he has been with the Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University. His current research interests are the microstructure characterization of various ceramic materials, cathode materials of lithium ion batteries and functional oxide thin films by the state-of-the-art spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM) techniques to reveal the synthesis-microstructure-property relationships and the related physical mechanisms.