Microwave Dielectric Materials with Defect-Dipole Clusters Induced Colossal Permittivity and Ultra-low Loss

Microwave dielectric materials are of great interest due to their applications in communication technology. The intrinsically low dielectric permittivity (generally less than 100) of traditional microwave dielectric materials has limited their capability in reducing the device size and developing various applications. In this paper, we report a microwave dielectric material, (La + Nb) co-doped BaSnO3, which exhibits both frequency- and temperature-independent colossal permittivity (ϵ > 103) over the frequency range from 10 Hz to microwave region (∼1 GHz) while retaining the ultra-low dielectric loss of 4 × 10-4, equivalent to a quality factor Qf (GHz) ∼2500. Systemic defect analysis and density functional theory calculations suggest that negatively charged La and positively charged Nb octahedra are correlated adjacent to each other along the [110] direction, forming defect-dipole clusters, which lead to their microwave dielectric properties. This work presents insights on the development of microwave dielectric materials that offer many potentials for microwave dielectric devices and their associated applications in future communication technology.