Detailed x-ray diffraction analyses and correlation of microstructural and electromechanical properties of La-doped PZT ceramics
- Autor: Hammer, M; Hoffmann, MJ
- Quelle: JOURNAL OF ELECTROCERAMICS, 1998, Band 2, Heft 2, S. 75–83
- Detailed x-ray diffraction analyses and correlation of microstructural and electromechanical properties of La-doped PZT ceramics.
Abstract
The influence of the La-concentration (0.1-8 mole-%) on the
F-R/F-T-ratio and the c/a-ratio of mixed oxide derived stoichiometric
and 3 mole-% PbO excess containing PZT with a Zr/Ti-ratio near the
morphotropic phase boundary (53/47) was investigated by quantitative
X-ray diffraction analysis. Temperature dependent X-ray diffraction
measurements showed a decrease of the Curie-temperature for
La-additions > 0.5 mole-% but an increase for very low La-amounts (0.1
and 0.2 mole-%) in comparison to undoped samples. Obviously this
phenomenon indicates the influence of La-dopants on the vacancy
concentration and thereby on the stability of the crystal structure.
The change in vacancy concentration leads to a different densification
behavior for undoped and doped samples which could be shown by
dilatometric measurements. The observations were finally correlated to
measurements of dielectric constants and coupling factors which
additionally show a strong dependence on the PbO excess and the
microstructure (porosities, grain sizes and chemical inhomogeneities)
of PZT ceramics.