Multifarious polarizations in high-performance colossal permittivity titanium dioxide ceramics

The (La1/2Ta1/2)(x)Ti1-xO2 and (Er1/2Ta1/2)(x)Ti1-xO2 ceramics with x = 0.01 and 0.03 were synthesized by a conventional solid-state reaction. The analysis of EDS mapping, ac conductivity spectra, impedance analysis, XPS, and DC bias indicate that electrons-pinned defect-dipole (EPPD) polarization plays the main role in both the (La1/2Ta1/2)(0.01)Ti0.99O2 and (Er1/2Ta1/2)(0.01)Ti0.99O2 ceramics, while the interfacial polarization and hopping polarization are respectively highlighted by the (La1/2Ta1/2)(0.03)Ti0.97O2 and (Er1/2Ta1/2)(0.03)Ti0.97O2 ceramics. Besides, the dielectric responses reveals that the interfacial polarization and hopping polarization are much slower than EPDD polarization and lead to poor frequency-, temperature-stability and higher dielectric loss (tan delta). Then the conclusion can be drawn that the outstanding dielectric properties can be achieved only the EPDD polarization takes the absolute dominant position, and excellent properties are obtained in (Er1/2Ta1/2)(0.01)Ti0.99O2 ceramic with ultra-low loss of tan delta approximate to 0.0095 (@1 kHz) and excellent frequency, temperature and DC bias stability. (C) 2019 Elsevier B.V. All rights reserved.