Ultrahigh recoverable energy storage density (Wrec = 4.41 J cm−3) and efficiency (η = 88%) at low electric field (210 kV cm−1), over wide frequency (10–100 Hz) and temperature (20–200 °C) were achieved simultaneously for 0.85Bi0.5Na0.5TiO3-0.15Ca(Nb0.5Al0.5)O3 ceramics.

The environment-friendly materials exhibiting colossal permittivity play an increasingly important role in the electronics industry. In this work, (Tb 0.5 Ta 0.5 ) x Ti 1−x O 2 (x = 0, 0.005, 0.01, 0.02, and 0.04) ceramics with new defect clusters were fabricated to enhance the dielectric response. Significantly, all ceramic samples exhibit large dielectric constants (ε r > 10 4 ), whereas the ceramic with x = 0.005 exhibits an ultralow loss (tan δ) of about 0.008 at room temperature and 1 kHz. The origins of its excellent dielectric properties were revealed by XRD, X-ray photoelectron spectroscopy, and dielectric response analysis, which were mainly caused by defective dipoles associated with oxygen vacancies (𝑉 •• O ). These defective dipoles limiting the long-range hopping of electrons lead to the electron pinning effect. Additionally, the frequency spectrum under DC bias and conductivity behavior suggests that grain boundary and electrode effects also contribute to the dielectric constant. This study not only explores the dielectric response properties of a new giant dielectric (Tb 0.5 Ta 0.5 ) x Ti 1−x O 2 ceramics but also offers a candidate material suitable for ceramics capacitors.

The development of ceramic capacitors featuring high reliability and superior comprehensive performance is vital for practical applications in the medium electric field. In this work, a synergistic strategy was proposed...