High breakdown electric field in (Ta1−xPrx)0.03Ti0.97O2 colossal permittivity ceramics through defect chemistry optimization

In this work, a novel (Ta1−xPrx)0.03Ti0.97O2 (x = 0.3, 0.5, 0.7 and 0.9) ceramic was fabricated via a solid-state reaction (SSR) method using an efficient defect engineering strategy, and the microstructure, breakdown electric field and charge transport processes were investigated in detail. All co-doped ceramics exhibit a pure rutile structure and the grain size is effectively refined by Pr/Ta ion doping. Notably, the ceramic sample with x = 0.9 displays a low tanδ of 0.018 and a large ε' of 1.74 × 104, enhancing temperature stability from RT to 200 ◦C (Δε′(T)/ε′30 = 1.5%, at 1 kHz) and Eb of 2.07 kV/cm. XPS and complex impedance spectroscopy analyses show that the excellent electrical properties of (Ta1−xPrx)0.03Ti0.97O2 ceramics originate from grains with electron-pinned defect dipoles (EPDD) and insulating grain boundaries. The (Ta1−xPrx)0.03Ti0.97O2 ceramics possess enhanced breakdown field strength and excellent giant dielectric properties, making them potential candidates for capacitors.