NOVEL PIEZOELECTRIC CERAMICS: DEVELOPMENT OF HIGH TEMPERATURE, HIGH PERFORMANCE PIEZOELECTRICS ON THE BASIS OF STRUCTURE

Open Access
Author:
Eitel, Richard Edward
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
October 02, 2003
Committee Members:
  • Clive A Randall, Committee Chair
  • Thomas R Shrout, Committee Chair
  • David John Green, Committee Member
  • Susan E Trolier Mckinstry, Committee Member
  • Leslie Eric Cross, Committee Member
Keywords:
  • piezoelectric
  • ferroelectric
  • bismuth
  • lead titanate
  • perovskite
  • ceramic
  • tolerance factor
  • Curie temperature
Abstract:
A new family of morphotropic phase boundary (MBP) perovskite solid solutions based on (1-x)BiMeO3-xPbTiO3 has been discovered. These materials promise both high piezoelectric properties, characteristic of MPB systems, and usage temperatures unavailable in current high performance piezoelectric systems. The discovery of this family of bismuth perovskite-lead titanate materials was made using simple crystal chemistry arguments based on the perovskite tolerance factor. In the current work, the details of the (1-x)BiScO3-xPbTiO3 (BSxPT) solid solution will be presented as the “prototype” example of this new family of materials. The optimum processing conditions and electromechanical properties of the BSxPT system were determined. X-ray diffraction, electron microscopy, dielectric measurements, and calorimetery were used to determine the details of the phase diagram, crystal structure, and domain structure. The intrinsic and extrinsic contributions to the dielectric and piezoelectric properties were determined using cryogenic dielectric measurements and a novel application of the Rayleigh Law to the direct piezoelectric response. The nature of the phase transition behavior in the tetragonal region of the BSxPT phase diagram was explored based on the Landau phenomenological approach. The BSxPT system represents a breakthrough in the field of piezoelectric ceramics. For the first time ever, a MPB piezoelectric material system has been developed with a transition temperature higher than Pb(Zr,Ti)O3 and improved piezoelectric properties. A detailed understanding of the structure, electromechanical response, and phase transition behavior of this exciting new system has been obtained. Further, a roadmap for the continued development of new materials in family (1-x)BiMeO3-xPbTiO3 was developed.