High dielectric permittivity and ultralow dielectric loss in Nb-doped SrTiO₃ ceramics

In this study, we prepared a series of Nb-doped SrTiO₃ ceramics sintered in both air and N₂ atmospheres. The X-ray diffraction (XRD) analysis indicated that all samples had a pure cubic phase perovskite structure with no secondary phase. The dielectric test showed that the Nb-doped SrTiO₃ ceramics had a high dielectric permittivity (>3 × 10⁴) and low dielectric loss (<0.004) over a broad temperature range from −100 to 300 °C with a breakdown strength over 20 kV/cm. The dielectric performance is attributed to the designated Ti_Ti^′−V_O^··−Ti_Ti^′ deep-lattice-defect states localising weak-hopping electrons to generate high defect-dipole concentrations, as verified by systematic X-ray photoelectron spectroscopy (XPS) experiments. This study offers a route for designing other types of high dielectric permittivity ceramics.