In this work we report on the elastic hysteretic behavior observed in ferroelectric lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT) relaxor single crystals under conditions of cooperative stress, temperature, and electric field. Room temperature elastic response displays strong and sharp discontinuity associated with stress induced phase transition. Quasistatic elastic response and ultrasonic wave propagation measurements demonstrated that this strain discontinuity in PIN-PMN-PT single crystal is associated with a ferroelectric rhombohedral (FR)—ferroelectric orthorhombic (FO) phase transition. The temperature dependent elastic response and transition strain were modeled by Devonshire theory. The crystal instability under compression is significantly improved by application of a dc bias electric field.

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PMNT single crystals in the relaxor-ferroelectric lead magnesium niobate (PMN)-lead titanate (PT) system provide significant advantage for underwater sonar transducers. Compared to lead zirconate titanate (PZT) ceramics, the large electromechanical coupling factor provides significant increases in transducer bandwidth. The superior strain energy density generates higher source level across the band, and the lower Young's modulus allows considerably smaller transducers. These payoffs occur even when PMNT crystals are subject to navy operating conditions such as uniaxial mechanical compressive stresses up to 42 MPa, electric fields up to 1.2 MV/m, and a temperature range from 5 to 50 degrees C. The impact of navy-relevant electric fields and mechanical stresses on crack propagation and failure of piezoelectric single crystals is investigated. The compressive, flexural, and tensile strength of PMNT crystals is reported and discussed with respect to conventional PZT ceramics and the operating conditions of a typical naval transducer.

Investigations of the polarization versus electric field (P-E) and strain versus electric field (ε-E) responses for “hard” Pb(Zr1−xTix)O3 piezoelectric ceramics have been performed under various uniaxial stresses (σ) and ac electrical drive fields. Investigations revealed a significant decrease in the remanent polarization of specimens with increasing σ. Subsequent calculations of the longitudinal electromechanical coupling coefficient (k33) and acoustic power density revealed significant enhancements with increasing σ.

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