Thermal stable and ultralow dielectric loss in (Gd_0.5Ta_0.5)_xTi_1-xO₂ giant permittivity ceramics by defect engineering

High dielectric loss and poor temperature stability are the current barriers to the application of dielectric materials. In present work, we synthesized a system of acceptor Gd³⁺ and donor Ta⁵⁺ co-doped (Gd_0.5Ta_0.5)_xTi_1-xO₂ (GTTOx, x = 0, 0.01, 0.02, 0.04, 0.06) ceramics to enhance dielectric response. It was found that a colossal permittivity (CP, 2.65 × 10⁴@1 kHz, 2.37 × 10⁴@1 MHz), a very low dielectric loss (tanδ, 0.007@1 kHz, 0.03@1 MHz), good stability of frequency (20–10⁶ Hz) and temperature (RT–250 ℃, Δε′ (T)/ε′₃₀ < ± 15%, at 1 kHz) were achieved simultaneously in GTTO0.01 ceramic. Complex impedance spectroscopy, XPS, SEM, and Raman spectroscopy were used to investigate the reasons for the improved dielectric properties. The result indicated that the main reasons for CP and low dielectric loss are the synergistic effect of the electron pinning defect-dipole (EPDD) model, the internal blocking layer capacitance (IBLC) mechanism, and electrode response. This work provides a promising approach for the design of defect-related high-performance giant dielectric ceramics.