Nanoindentation Based Estimates of Flexoelectric Properties of Piezoelectric Crystals
Abstract
Flexoelectricity refers to coupling between electric polarization and strain
gradients in crystalline dielectrics. Recent work has shown that stiffness data obtained by
nanoindentation, combined with an analytical indentation model that predicts size
dependent behavior attributable to flexoelectricity, may be used to characterize
flexoelectric properties of piezoelectric crystals. In the present work this experimental-analytical
method is used and evaluated based on nanoindentation of quartz, lithium niobate,
lithium tantalate, lead magnesium niobate - 30% lead titanate, and barium titanate with Berkovich, cone, and cube
corner indenters. Flexoelectric properties appear negligible in quartz and are estimated to
be on the order of 10^-9C/m to 10^-8C/m in lithium niobate and lithium tantalate, and around 10^-4C/m for
barium titanate and PMN-30%PT. The results for quartz agree with previous work, the results
for barium titanate conflict, and those for the remaining materials are original and justifiable.
Implications of the approach are discussed at length. The methodology in its current state
is practical for specific types of dielectric crystals.