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

In this study, we prepared a series of Nb-doped SrTiO 3 ceramics sintered in both air and N 2 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 SrTiO 3 ceramics had a high dielectric permittivity (>3 × 10 4 ) 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 T i T i ′ − V O · · − T i T i ′ 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. • Synthesized a novel Nb-doped SrTiO 3 ceramics with dense and fine-grained microstructure. • Achieved giant permittivity of 3 × 10 4 and low loss (<0.004) at room temperature. • The designated deep-lattice-defect states localize weak-hopping-electrons to generate high defect-dipoles concentration.