Lithium Niobite (LiNbO3) is an optically transparent, piezo responsive material used, for example, in piezo sensors or in mobile phones. We tested a LiNbO3 sample (PFM03, obtained from TipsNano, Estonia) with CoreAFM. The sample has a regular domain structure with 10-µm period. The spontaneous polarization has the opposite direction in the neighboring domains.
To measure the piezoresponse during imaging, a 30kHz AC voltage with 5V amplitude was applied to the cantilever while raster scanning the tip over the sample. In response to the applied voltage, the sample periodically expands and shrinks, either in phase with or in counter phase to the excitation frequency. The periodic expansion is measured by the second internal lock-in amplifier of the CoreAFM controller and revealed a 180° phase shift between the domains.
Image size: 20 µm
Image processing was done with MountainsSPIP
Image courtesy: Brian Odermatt, EPFL, Lausanne