Domain wall displacements and piezoelectric activity of KNbO3 single crystals

The role of domain-orientation effects in forming the piezoelectric coefficient d33 of polydomain KNbO3 single crystals in the mm2 phase is studied. Non-180DG domain wall displacements in the electric field E BB [001] are analysed, and their contributions to d33 are evaluated. A link between these contributions and crystallographic characteristics of domain structures is revealed for the first time for different 60DG, 90DG and 120DG domain structures. The problem of the relationship between piezoelectric performances and domain structures of ferroelectric single crystals (SCs) has been the subject of various studies in the last years. Perovskite-type SCs are of scientific significance due to the perspective of the search for specific domain patterns (or so-called engineered domain structures), heterophase structures, optimal crystallographic orientations or poling treatment conditions that lead to improved piezoelectric properties and high electromechanical coupling factors.