Nanoscale probing of electromechanical responses by scanning probe microscopy: from piezoresponse to electrochemical strain

Date: 
03/25/2014 - 3:30pm to 4:30pm
Location: 
CP179
Speaker(s) / Presenter(s): 
Sang Mo Yang (Oak Ridge National Laboratory)
Type of Event (for grouping events):

Electromechanical responses (the mechanical displacement induced by an applied electric field, and vice versa) are ubiquitous in nature. One of the most typical examples is converse piezoelectric response in ferroelectric and multiferroic materials. Another example is electrochemical strain induced by ionic motion, e.g., in Li-ion batteries and solid oxide fuel cells. Here, the recent scanning probe microscopy studies of those electromechanical responses in a variety of material systems are presented. First, the piezoresponse force microscopy (PFM) study on the origin of polarization fatigue in epitaxial ferroelectric Pb(Zr,Ti)O3 capacitors will be shown [1]. In this study, PFM allows to visualize ferroelectric domain nucleation and growth during the fatigue process at the nanoscale time and length scales. It reveals that the evolution of domain wall pinning process is the primary origin of polarization fatigue, which has been a long-standing important problem in ferroelectrics. Second, the electrochemical strain microscopy (ESM) study on the nonlinear electromechanical responses in Ag-ion based ionic conductive glasses will be presented. ESM has recently emerged as a powerful tool to probe ionic transports and electrochemical phenomena at the nanoscale in many material systems [2]. In this study, interesting anti-
correlation between the first and second harmonic ESM responses are observed, and its possible origins are discussed.

[1] S. M. Yang et al., Adv. Funct. Mater. 22, 2310 (2012).
[2] N. Balke et al., Nat. Nanotechnol. 5, 749 (2010).

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