High-performance colossal permittivity for textured (Al+Nb) co-doped TiO2 ceramics sintered in nitrogen atmosphere.

Al 0.15 Nb 0.15 Ti 0.7 O 2 ceramics were synthesized via strong magnetic field alignment at 6 T and sintered under a nitrogen atmosphere. A ceramic prepared at 6 T by polishing it along the direction parallel to the magnetic field (parallel-6 T) with a brick-layered microstructure shows a colossal permittivity of ε r ≈ 8.2 × 104 and a low dielectric loss of tan δ ≈ 0.019 at 1 kHz, with impedance spectroscopy suggesting that the colossal permittivity is attributed to internal barrier layer capacitor effects. XRD results indicate that approximately 90 % of the grains are aligned along the magnetic field with a tilt angle less than 10°. The average width and length of the grains for parallel-6 T ceramics are 4.1 μm and 9.4 μm. Compared to non-magnetically treated Al 0.15 Nb 0.15 Ti 0.7 O 2 ceramics, the high grain boundary resistance (1.6 × 108 Ω cm) of the parallel-6 T ceramic can be responsible for this low dielectric loss. [ABSTRACT FROM AUTHOR]