Nanoscale electromechanical properties of CaCu3Ti4O12 ceramics
authors Tararam, R; Bdikin, IK; Panwar, N; Varela, JA; Bueno, PR; Kholkin, AL
nationality International
journal JOURNAL OF APPLIED PHYSICS
keywords PIEZORESPONSE FORCE MICROSCOPY; HIGH-DIELECTRIC-CONSTANT; THIN-FILMS; FLEXOELECTRIC POLARIZATION; FERROELECTRICS; TITANATE; HYSTERESIS
abstract Piezoresponse Force Microscopy (PFM) is used to characterize the nanoscale electromechanical properties of centrosymmetric CaCu3Ti4O12 ceramics with giant dielectric constant. Clear PFM contrast both in vertical (out-of-plane) and lateral (in-plane) modes is observed on the ceramic surface with varying magnitude and polarization direction depending on the grain crystalline orientation. Lateral signal changes its sign upon 180 degrees rotation of the sample thus ruling out spurious electrostatic contribution and confirming piezoelectric nature of the effect. Piezoresponse could be locally reversed by suitable electrical bias (local poling) and induced polarization was quite stable showing long-time relaxation (similar to 3 hrs). The electromechanical contrast in unpoled ceramics is attributed to the surface flexoelectric effect (strain gradient induced polarization) while piezoresponse hysteresis and ferroelectric-like behavior are discussed in terms of structural instabilities due to Ti off-center displacements and structural defects in this material. (C) 2011 American Institute of Physics. [doi:10.1063/1.3623767]
publisher AMER INST PHYSICS
issn 0021-8979
year published 2011
volume 110
issue 5
digital object identifier (doi) 10.1063/1.3623767
web of science category Physics, Applied
subject category Physics
unique article identifier WOS:000294968600020
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