Date : 2012. 5. 21, 5:00 PM Place : Rm.L309, Bldg.500 -Abstract- Ferroelectricity continues to arouse intense interest due to its potential applications in nonvolatile data storage and solar energy harvest. With recent advances in synthesis and processing, various forms of ferroelectric materials are now available, such as nanoparticles, epitaxial thin films, and single crystals. An intriguing, challenging question is how ferroelectric ordering cope with electrical and mechanical boundary conditions, especially in reduced dimensions. Combining in situ electrical biasing in transmission electron microscopes and atomic-scale imaging using aberration-corrected scanning transmission electron microscopy, unit-cell scale dipole moments and two-dimensional electric fields associated with macroscale polarization in individual BaTiO3 nanocubes, Pb(Zr,Ti)O3 thin films, and hexagonal ErMnO3 crystals are quantitatively mapped out. Fundamental size-limit of ferroelectric ordering, rectifying-junction effects on polarization switching, and atomic structure of ferroelectric domain walls interlocked with structural phase boundary will be discussed in detail.