Extrinsic contributions to the response in ferroelectric ceramics

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7166524

Li, S

The interest of this thesis is to investigate the electromechanical properties of ferroelectric ceramics in terms of the motion of domain walls, movement of boundaries between interphases, and interactions between grains and domains. A tentative phenomenological model has been proposed to evaluate the piezoelectric, elastic and dielectric parameters attributed to non-180[degrees] domain wall motions in ferroelectric ceramics. Observations of dielectricity and piezoelectricity at low and high temperatures, at small and large external fields, and at medium and high frequencies are discussed. From observed linear and nonlinear behavior of PZT ceramic systems, it can be concluded that the nonlinear effects are essentially extrinsic in nature, and domain wall motions play a major role in terms of the electromechanical coupling coefficients. Through X-ray diffraction analysis, the 90[degrees] domain reorientations under both electric fields and stress fields induced by the abrasion were examined in PZT ceramics, which showed that the coercive field is dependent upon 90[degrees]-domain reorientation processes. A simple and direct method has been proposed for quantitatively distinguishing the mechanisms of domain reorientation processes in polycrystalline materials. The polarization switching processes in the PZT ceramic with compositions near the morphotropic phase boundary is predominantly dependent upon two successive 90[degrees] domain wall reversal processes. Characterization of the domain structure has been made by scanning electron microscopy and etching techniques. The domain structure and grain morphology in PZT ceramics have been observed at the same time through SEM without using a coating technique. A modified lumped parameter method has been proposed suitable for microwave measurements of ferroelectric materials in the frequency range 10 MHz to 1G Hz. The dispersion of the complex dielectric coefficients of PZT ceramics was measured between 100 KHz-1 GHz.

• Research Organization: Pennsylvania State Univ., University Park, PA (United States)
• OSTI ID: 7166524
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
DIELECTRIC PROPERTIES
DOMAIN STRUCTURE
ELASTICITY
ELECTRICAL PROPERTIES
ELECTRICITY
FERROELECTRIC MATERIALS
GRAIN BOUNDARIES
LEAD COMPOUNDS
MECHANICAL PROPERTIES
MICROSTRUCTURE
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PIEZOELECTRICITY
PZT
TENSILE PROPERTIES
TITANATES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ZIRCONATES
ZIRCONIUM COMPOUNDS