Dielectric relaxation behavior of Mn-modified Ca0.9Pr0.05[]0.05Bi2Nb2O9 -based high temperature piezoceramics

Pr/Mn- codoped Aurivillius type Ca0.95[]Bi2Nb2O9 ([] denoted as A-site vacancies) piezoelectric ceramics were prepared by a conventional solid state sintering method. The microstructure and correlated electrical properties were investigated. A set of dielectric relaxation peaks was observed in the high doping level of Pr/Mn-doped CBN ceramics. The primary and secondary processes dominate the dc conduction and dielectric relaxation processes owing to various activation energies. The localized hopping of oxygen vacancies near the Mn doping centers causes the dielectric relaxation behavior. On the other hand, the long-range continuous transformation of oxygen vacancies is responsible for the dc conduction process, which has a higher energy barrier than that of the localized hopping. The thermal depolarization behavior of piezoelectric properties was also studied.