简介: |
摘要：Ferroelectric materials show a hierarchy of structure and associated dynamic behavior, and thus obtaining deep insights into them necessitates probing at various length/time scales. The prevalence of piezoresponse force microscopy (PFM), a scanning probe modality, has largely fulfilled the task of mesoscopic imaging of ferroelectric domains. PFM can also be adapted to probe a range of locally/globally induced dynamic phenomena that are closely tied in with material functionalities, for instance, polarization switching, phase transitions and ion migration activities. In this talk, I will first present my development of a near-field ultrasound elastic spectroscopy based on multi-frequency PFM and its case studies of morphotropic phase transitions in BiFeO3 thin films, which led to the first observations of highly spatially-confined lattice elastic softening behavior due to the phase instabilities. In the second part, I will explore the coupling mechanism between oxygen vacancy transport and polarization evolution in Pb(Zr,Ti)O3 thin films, which may provide a revised explanation for the tip-pressure induced ferroelectric switching phenomena currently attributed to flexoelectricity. Apart from PFM, my talk will emphasize the combination of phase-field modeling in understanding those complex mesoscale phenomena, and also briefly illustrate our recent initiative of correlative mesoscale structural characterization using full-field X-ray Bragg diffraction imaging.
报告人简介：李千，2003至2010年就读于南京航空航天大学材料系，2010年至2014年在澳大利亚国立大学化学研究院就读并获得博士学位，其中于2013年获得国家优秀自费留学生奖学金。2014年至今在美国橡树岭国家实验室纳米相材料科学研究中心从事博士后研究。主要的研究经历和兴趣方向有: 铁电压电材料与超声驱动器件，扫描探针显微术，同步辐射X射线与中子散射（包括非弹性散射、衍射显微成像以及超快衍射），有限元相场模拟以及大数据分析方法等。目前以在Nature Communications, ACS Nano, Advanced Functional Materials等国际期刊上发表论文近40篇，引用近400次。 |
