Frequency dependent properties of high permittivity PMNT piezoelectrics for ultrasonic transducer applications

Pb(Zr,Ti)O
3
-5H piezoelectric ceramics are widely used in medical ultrasonic applications due to their high electromechanical coupling (k
33
≤ 75%). However, their relatively low clamped dielectric permittivity (≪ 1500) limits their usefulness in high frequency medical transducers with small aperture and array elements. Thus, high permittivity piezoelectric materials are desired. Relaxor based Pb(Mg
1/3
Nb
2/3
)O
3
-PbTiO
3
(PMNT) piezoelectrics with high permittivity and coupling have attracted much attention in medical ultrasonic applications in the form of both polycrystalline and single crystals.