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Viehland. Microstructures 2023;3:2023016 Microstructures
DOI: 10.20517/microstructures.2023.10

Commentary Open Access

Commentary on “Heterogenous nature of enhanced

piezoelectricity in relaxor-ferroelectric crystals”

D. Viehland
Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061, USA.

Correspondence to: Prof. D. Viehland, Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061, USA. E-mail:
dviehlan@vt.edu

How to cite this article: Viehland D. Commentary on “Heterogenous nature of enhanced piezoelectricity in relaxor-ferroelectric
crystals”. Microstructures 2023;3:2023016. https://dx.doi.org/10.20517/microstructures.2023.10

Received: 16 Feb 2023 Accepted: 17 Feb 2023 Published: 9 Mar 2023

Academic Editor: Shujun Zhang Copy Editor: Fangling Lan Production Editor: Fangling Lan

Enhanced piezoelectricity in Pb-based perovskite ferroelectric single crystals has been of research interest
[1]
for about 30 years since the early reports by Uchino of high weak-field properties (d33~1500 pC/N) to
[2]
subsequent ones by Park et al. of large field-induced strains (ε = 1.5%, E = 120 kV/cm). The fundamental
scientific question of what causes the enhanced piezoelectricity of the Pb(Mg Nb )O -PbTiO (PMN-PT)
3
3
1/3
2/3
or Pb(Zn Nb )O -PbTiO (PZN-PT) type piezoelectric crystals naturally arose, as it has the potential to
3
1/3
2/3
3
help guide ultrahigh piezoelectricity by design.
In the United States, under the support of the Office of Naval Research or ONR (Smith), much effort was
expended to develop a theory of intermediate monoclinic (M) phases that structurally bridge rhombohedral
(R) and tetragonal (T) ones across the morphotropic phase boundary (MPB) . Ab-initio approaches
[3]
predicted a monoclinic unit cell, indicating an intermediate M phase that is structurally homogeneous. The
polarization vector within the unit cell rotated on application of electric field E, resulting in
electromechanical transduction.
However, it must be remembered that the perovskite crystals which exhibit ultrahigh piezoelectricity are in
solid solutions between end members having relaxor and normal ferroelectric behaviors. Relaxors are
unique in that they are characterized by a structural heterogeneity of lower symmetry within an average
cubic state . Figure 1A shows data taken from the same (001) PMN-32at%PT crystal under different
[4]
electrical histories. In the annealed condition (dotted lines) , typical relaxor ferroelectric behavior is
[5]

© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0
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