What Do We Know About Surface Charges on Cracks in Ferroelectric Ceramics?
The present work investigates the static and time dependent electric potential distribution around cracks in a poled ferroelectric ceramic by Kelvin Probe Force Microscopy (KFM). In a first step a Vickers indentation crack in poled lead zirconate titanate (PZT) was subjected to static electric fields of up to 500V/mm in poling direction, and the potential distribution around the crack was measured. In a second step, the polarity of the applied voltage was reversed against the poling direction during the measurement of the potential. Using a simple model, an effective dielectric constant of the crack, as well as the surface charge density on the crack face were calculated as a function of the distance from the crack tip, the applied field and the time. The results are discussed with reference to free charges on the crack surface, electrically induced domain switching at the crack tip and crack bridging.
KeywordsCrack Surface Applied Electric Field Crack Opening Displacement Crack Path Surface Charge Density
We thank Rodrigo Pacher Fernandez and Claudia Neusel for the measurement of the electrical conductivity of PZT and the DFG (German Science Foundation) for supporting this project under the grant number SCHN 372/12-2.
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