High‐K Dielectric Ceramics from Donor/Acceptor‐Codoped (Ba1−xCax)(Ti1‐yZry)O3 (BCTZ)

Abstract
(Ba1−xCax)(Ti1−yZry)O3 ceramics doped with various donors and acceptors were sintered in a reducing atmosphere and then annealed at different oxygen partial pressures. The dielectric maxima at the Curie point increased up to ∼30000 after reoxidation, depending on the grain size, the type of acceptor, and the annealing conditions. The increase of the dielectric maxima seems to be correlated with oxidation of the grain boundaries. The dielectric properties show relaxation effects with increased frequency.