Rare-earth substituted piezoelectric PbTiO3 ceramics for acoustic wave applications

Abstract

Electromechanical and surface acoustic wave (SAW) properties of PbTiO3, ceramics modified by partial substitution of rare-earth for the Pb, specifically (Pb, Ln) (Ti, Mn)O3 (Ln=La, Ce, Pr, Nd, Sm, Eu, or Gd) ceramics, are extensively investigated. The SAW delay time temperature coefficient is found to be minimum when Ln=Nd. A zero temperature coefficient can be achieved in the (Pb, Nd) (Ti, In, Mn)O3 system with appropriate compositions. High frequency SAW filters are fabricated using these ceramics. It is also found that (Pb, Sm) (Ti, Mn)O3 ceramics have exceptionally large electromechanical anisotropy (ratio of electromechanical coupling factor for thickness vibration to that for planar vibration is above 15). A 7.5MHz linear array ultrasonic probe employing these ceramics is developed for medical use.