Synergistic enhancement of dielectric properties in Sr0.985Lu0.01TiO3 ceramics via Ta doping and nitrogen annealing

This study investigates the synergistic enhancement of tantalum (Ta) doping and nitrogen (N 2 ) annealing on the dielectric properties of Sr 0.985 Lu 0.01 Ti 1-x Ta x O 3 (x = 0, 0.01, 0.015, and 0.02) ceramics. X-ray diffraction (XRD) confirmed the presence of the primary SrTiO 3 phase along with a minor secondary phase of Lu 2 Ti 2 O 7 . XPS, Raman, and UV-vis spectroscopy analyses revealed the formation of defect dipoles including [Ti 3+ - , [ - ], and [Ti 3+ - - Ti 3+ ], induced by Ta doping and N 2 annealing. The combined effects of electron-pinned defect dipole (EPDD, obtained from defect dipoles), along with interface polarization (induced by phase boundaries), resulting in ultra-low dielectric loss and excellent thermal stability. Notably, the Sr 0.985 Lu 0.01 Ti 0.985 Ta 0.015 O 3 ceramic, which was sintered in air and subsequently annealed in N 2 at 1325 o C, exhibited a high permittivity (εᵣ ∼ 162,000), ultra-low dielectric loss (tanδ ∼ 0.013), and excellent thermal stability (-55 o C to 125 o C, Δε′ / ε′ 25 °C ≤ ± 15%) at 1 kHz. This study can provide a way to improve the properties of colossal permittivity materials.