As-grown ferroelectric domain structure with charged domain walls in single crystalline lead germanate (Pb₅Ge₃O₁₁) after partial decay  in ac electric field. Visualization by piezoresponse imaging mode (PRIM). Upper image - topography obtained in contact atomic force microscopy mode. Center and bottom images are signals measured as  phase shift between mechanical oscillations of cantilever caused by reversed piezo effect and driving electrical voltage oscillations  applied between conducting probe and sample bottom electrode. Center phase image was recorded simultaneously with topography image. Bottom image corresponds to green box in the center image.
Images were obtained by Georgy Batog, NT-MDT.
Sample courtesy of Prof. Vladimir Shur, Laboratory of Scanning Probe Microscopy, Ural State University, Ekaterinburg, Russia. (labfer.usu.ru, spm.usu.ru)