Dislocation-Enhanced Pyroelectricity in Barium Titanate.

Abstract

Pyroelectric materials hold significant promise for thermal sensing, imaging, and energy harvesting, with the pyroelectric coefficient serving as the key figure of merit. While intrinsic lattice optimization, particularly through zero-dimensional point defects, has improved pyroelectric properties, extrinsic contributions from mobile ferroelectric domain walls have remained underexplored. Here, a dislocation-based one-dimensional mechanical doping strategy is proposed to enhance the pyroelectric response of classical ferroelectric BaTiO₃ single crystals. By employing high-temperature plastic deformation, anisotropic dislocation networks are produced that introduce localized stress concentrations and thermal expansion/contraction effects, which amplify domain-wall motion. These directional strain fields, combined with phonon-dislocation interactions, lead to an anisotropic coupling of thermal and electrical fields. While the enhanced phonon scattering reduces thermal conductivity, the strong dislocation-domain-wall coupling leads to an increase in the temperature sensitivity of polarization and accelerates domain switching, effectively compensating for the reduced heat transport. As a result, the maximum pyroelectric coefficient exceeds 600 nC cm^- ² K^- ¹, representing a 38-fold increase compared to the undeformed counterpart. Structural evolution is revealed by synchrotron scanning X-ray diffraction microscopy and transmission electron microscopy, while multiscale phase-field simulations corroborate the underlying mechanism. Our work establishes dislocation engineering as an effective new pathway towards domain-wall-mediated enhancement of pyroelectric functionality.