Achievement

Materials Science trainee Mark Polking has been examining the atomic-scale nature of ferroelectric polarization in colloidal nanocrystals of the prototypical perovskite ferroelectric BaTiO3. This work seeks to answer longstanding questions concerning the nature of ferroelectric ordering in low-dimensional nanomaterials and to find conclusive experimental evidence of the elusive vortex polarization state. These nanocrystals have been imaged with atomic resolution using the aberration-corrected TEAM 1 microscope at the National Center for Electron Microscopy, and the atomic displacements that generate the spontaneous polarization are being examined. In addition, the electrostatic potential gradient associated with the polarization has been directly imaged using off-axis electron holography in collaboration with researchers at Brookhaven National Laboratory.