Fabrication and properties of radially 〈001〉C textured PMN-PT cylinders for transducer applications

Abstract

〈001〉C Textured PMN-PT ceramics have electromechanical properties (d33 = 850–1050 pm/V, k33 = 0.79–0.83) between those of conventional PZT ceramics and relaxor PMN-PT crystals. In this work, we tailor crystallographic orientation in textured PMN-PT ceramics for transducer designs with non-planar poling surfaces. Specifically, omni-directional cylindrical transducer elements were fabricated using monolithic, radially 〈001〉C textured and poled PMN-PT ceramic. Texture was produced by templated grain growth using NBT-PT templates, which were oriented radially by wrapping green ceramic tapes around a cylindrical mandrel. Finished transducer elements measure ∼5 cm in diameter by ∼2.5 cm in height and demonstrate scalability of textured ceramic fabrication techniques. The fabricated cylinders are ∼50 vol. % textured and show high 31-mode electromechanical properties compared to PZT ceramics (d31 = −259 pm/V, k31 = 0.43, ɛT33 = 3000, and Qm = 350). Frequency bandwidth is related to the square of the hoop mode coupling coefficient kh2, which is ∼60% higher in textured PMN-PT cylinders compared to PZT 5H. Finite element simulations show that this parameter may be further increased by improving texture quality to ≥90 vol. %. Radially textured PMN-PT may thus improve performance in omni-directional cylindrical transducers while avoiding the need for segmented single crystal designs.