Piezoelectricity and electrostriction in ferroelastic materials with polar twin boundaries and domain junctions
GM Lu and SZ Li and XD Ding and EKH Salje, APPLIED PHYSICS LETTERS, 114, 202901 (2019).
Weak piezoelectricity, compared with electrostriction, occurs in twinned ferroelastic materials even when the uniform bulk material is centro- symmetric. In a simple computer simulation, polarity is exclusively generated by the flexoelectric effect. Simple twinned structures (parallel twin walls) are electrostrictive and show no piezoelectricity. Complex twinned structures break inversion symmetry by the simultaneous appearance of junctions, kinks, needle domains, etc. Such structures show weak piezoelectricity (d approximate to 10(-4)pm/V) under periodic boundary conditions together with significant electrostriction. The macroscopic piezoelectric response is stronger (d approximate to 10(-3)pm/V) under free boundary conditions due to the effect of relaxing surfaces.
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