DIELECTRIC, PYROELECTRIC, AND THERMALLY STIMULATED DEPOLARIZATION CURRENT INVESTIGATIONS ON LEAD-LANTHANUM ZIRCONATE-TITANATE-X/95/5 CERAMICS WITH LA CONTENT X = 0.5-PERCENT-4-PERCENT

It is shown that La dopants have a strong influence on the antiferroelectric-ferroelectric-paraelectric (AFE-FE-PE) phase transitions and properties of the lead-lanthanum zirconate-titanate-x/95/5 ceramics (with La contents x = 0.5%-4%). The occurrence of the ferroelectric microdomains, dispersed in the AFE and PE matrices, gives rise to properties typical for ferroelectric relaxors. The space-charge concentration polarization, formed by some mobile ion defects, plays an important role in this behavior. This space-charge polarization and its interaction with the spontaneous polarization was investigated by dielectric, pyroelectric, and thermally stimulated depolarization current measurements. A qualitative model of interpretation is discussed.