Electric-field and stress effects on depoling and overpoling phenomena in [001]-poled transverse mode pb(zn_1/3nb_2/3)o₃-(6-7)%pbtio₃ single crystal of [110] length cut

Solid-solution Pb(Zn_1/3Nb_2/3)O₃-PbTiO₃ (PZN-PT) single crystals, touted as next-generation piezoelectric materials, have been studied extensively in the past decade. This work addresses the advantages and limitations of transducers made of transverse mode PZN-(6-7)%PT single crystals of [110]^L × [001]^T(P) cut. This cut exhibits superior electromechanical properties, with k₃₁ ≈ 0.85 and d₃₁ ≈ -1450 pC/N, and an extremely high d₃₁/S_E¹¹ value of >;35 C/m². It also has relatively high overpoling, i.e., rhombohedral-to-tetragonal phase transformation, field of ≈2 kV/mm. This overpoling field further decreases with increase in axial compressive stress. Despite these good attributes, this crystal cut has a low depoling field of ≤0.3 kV/mm, a result of low coercive fields of [001]-poled relaxor-based single crystals, which decreases further with increasing axial compressive stress, limiting its bipolar drive capability. The axial compressive stress required to cause overpoling via rhombohedral-to-tetragonal phase transformation of relevant domain variants in the crystal is found to be >;90 MPa. In contrast, this crystal cut depolarizes at comparatively low axial tensile stress of ≈15 MPa, the magnitude of which is not significantly affected by the moderate forward field applied.