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Solid-solution Pb(Zn1/3Nb2/3)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 L × T(P) cut. This cut exhibits superior electromechanical properties, with k31 ≈ 0.85 and d31 ≈ -1450 pC/N, and an extremely high d31/SE11 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 -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.
Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on (Volume:58 , Issue: 9 )
Date of Publication: September 2011