Local Electromechanical Response in Doped Ceria: Rigorous Analysis of the Phase and Amplitude

Characterization of the ionic transport and corresponding electro-elastic deformations in cerium oxide at the nanoscale are important for the understanding of the mechanism of the local response under an external electric field, especially the mechanisms of the 'non-Newnham''-type giant electrostriction. Here, we introduce a methodological approach to the analysis of signals in the piezoresponse force microscopy/electrochemical strain microscopy allowing decoupling ionic motion, electrostriction, and electrostatic contributions to the electromechanical signals based on a precise analysis of the electromechanical amplitude and phase as a function of temperature, and AC and DC biases. The ionic motion was demonstrated to be hampered in a 30-300 degrees C temperature range, the typical operational range of commercial SPM microscopes. The local electromechanical response was interpreted as a mixture of the electrostatic-force-meditated response and conventional electrostriction.