题目: MBE growth, defect engineering, and properties of functional oxides

报告人：Ph.D. Yingge Du

Senior Research Scientist

Physical Sciences Division, Pacific Northwest National Laboratory

(509) 371-6512; yingge.du@pnnl.gov

摘要：

This talk will highlight the most recent research activities in our oxide epitaxy group where we aim to modify and control the structure and properties (e.g., electronic, optical, magnetic, and ion transport) of complex oxides.

Perovskite oxides exhibit a broad range of structural, compositional, and functional properties, which can be further tuned or even drastically transformed by means of judicious elemental doping and defect engineering. We show that Sr substitution of La in LaCrO3, a wide gap Mott insulator, can lead to hole doping into the top of valence band with the formation of Cr4+(3d2) and make SrxLa1-xCrO3 (x<0.25) a high performancep-type transparent conductive oxide (p-TCO). Using oxygen-assisted molecular beam epitaxy (MBE), all-perovskite pn junctions consisting of SrxLa1-xCrO3 (x = 0.125) films and Nb doped SrTiO3(001) (NbSTO) substrates were fabricated and characterized. At x > 0.65, hole-induced insulator-to-metal transition is observed, but only on the films with in-plane compressive strain. In particular, the end member, SrCrO3-d, under different strain states (compressive vs. tensile) displays drastically different phase stability and O2- ion transport properties, which is of considerable interest in solid oxide fuel cells where fast oxygen ion transport at lower operating temperature is highly desired. In another example, I will present how we tune the structure and electronic properties of WO3 epitaxial thin films, and use them as model cathode materials forin situ TEM studies. The atomic scale ion (Li+, Na+, and Ca2+) intercalation and conversion reactions are revealed by STEM, EELS, NBD, and theory.

简介：

Employment:

·         2010-present        Senior Research Scientist, Pacific Northwest National Laboratory (PNNL)

Education and Training:

·         2007-2009    Postdoctoral Research Fellow, PNNL

·         2001-2007    Ph.D., Engineering Physics, University of Virginia, Charlottesville, VA

          1998-2001    M.E., Engineering Physics, Tsinghua University, Beijing, China

       1994-1998            B.S., Engineering Physics, Tsinghua University, Beijing, China

Research Interests:

·         Structure-property relationships in epitaxial oxide thin films

·         Photochemistry and electrochemistry utilizing heteroepitaxial oxide structures

·         Development of in situ monitoring and control tools for materials synthesis and processing

Honors and Awards:

·         U.S. Department of Energy (DOE) Early Career Award (2016).

·         PNNL Outstanding Performance Award (2008, 2009).

·         Student Fellowship, University of Virginia (2005).

·         Summer Research Institute Research Fellowship, PNNL (2004).

·         Technology Innovation Award, Tsinghua University (2002).

       TongFang Scholarship, Tsinghua University (2001, 2002).

时间：2016年3月11日上午10：00

地点：中科院物理研究所M253会议室

联系人：金奎娟 研究员 （Tel：82648099）

邀请人：魏志义 研究员 （Tel：82648115）

主办单位：中国科学院光物理重点实验室