报告时间：2015年6月17日(星期三)上午9:00
报告地点：能源基础楼（原膜中心楼）一楼会议室
报 告 人：Yingge Du
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory
报告人简介
2006 Ph.D., Engineering Physics, University of Virginia, Charlottesville, VA
2001 B.S., M.E., Engineering Physics, Tsinghua University, Beijing, China
2010 - present, Sr. Research Scientist, Pacific Northwest National Laboratory
2007 – 2009, Postdoctoral Research Associate, Pacific Northwest Natioanl Laboratory
报告简介：
Complex oxides of perovskite structures exhibit a broad range of structural, compositional, and functional properties, which can be further tuned or even drastically transformed by means of judicious defect engineering. A challenging goal in material synthesis and processing is to generate novel structures and functions by exploiting collective behavior of defects. Herethrough two exampleswe demonstrate that desirable functional properties pertinent to energy conversion and storage can be achieved by defect engineering at the heteroepitaxial interfaces.
In the first example, we discuss how oxygen partial pressure and substrate-induced strain during molecular beam epitaxy (MBE) can impact the structure, electronic, and optical properties of WO3 epitaxial thin films. In addition, we revealthat oxygen defect formation and segregation can strongly impact the intercalation and conversion reactions upon small ion (Li, Na) insertion into the lattices through In-situ TEM studies. In the second example, we discuss how epitaxial strontium chromite films under compressive strain (grown on LaAlO3(001)) can be transformed, reversibly and at low temperature, from rhombohedral, semiconducting SrCrO2.8 (R-SCO) to cubic, metallic perovskite SrCrO3 (P-SCO). On the other hand, R-SCO under tensile strain (grown on SrTiO3(001)) retains its structural and chemical integrity under similar oxidizing environment. In R-SCO, the vacancies aggregate into {111}-oriented SrO2 planes interleaved between layers of tetrahedrally-coordinated Cr. In turn, these planes aggregate into ordered arrays so as the oxygen-deficient SrO2 planes are separated by ~1 nm. The structural motifs of the oxygen-deficient SrO2 planes allow for the Grotthuss-type mechanism of the oxygen ion diffusion with the potential energy barrier being significantly lower than that in the cubic SrCrO3. This property is of considerable importance in solid oxide fuel cells where fast oxygenion transport at lower operating temperature is highly desired.
报告联系人：502组 姜秀美（9128）
