Flexoelectricity

1
Active Electromechanical Nanostructures Without
the Use of Piezoelectric Constituents (NSF NIRT
Grant 0708096 ) Pradeep Sharma, University of
Houston Boris Yakobson, Rice University Ramanan
Krishnamoorti. University of Houston Zoubeida
Ounaies, Texas AM University
Theoretical results Effect of flexoelectricity
on indentation
Flexoelectricity
Apparently Piezoelectric Superlattices without
Piezoelectric Constituents
We derived analytical solution of the indentation
problem incorporating anisotropy,
piezoelectricity and flexoelectricity.
Layered Super-Lattices
Indentation experiments
In parallel, we conducted experiments with
varying indentation size..single crystal BaTiO3
Berkovich indent on BTO surface Load 8mN Depth
into surface 200nm
Polarization in each layer of a SrTiO3-MgO-BaTiO3
Periodic Trilaminate (as shown in the inset).
Overall average polarization in the Trilaminate
is 11 of the Quartz.
NaCl will exhibit an apparent piezoelectric
effect when subjected to strain gradients
Contact stiffness vs contact radius for BaTiO3
Indentation size effect?
Indentation experiments indicate a large size
effect (see the star-data points). For example,
compared to the size-independent behavior (red
line), around 10 nm, there is a doubling of
contact stiffness.
The curvature of CNT results in rehybridization
of p-orbital. As a result, the center of
electronic charge at each atomic site is
displaced outwards from the nuclear charge.
In principle, the flexoelectric size-effect
should be observable in indentation experiments.