Permittivity boosting by induced strain from local doping in titanates from first principles.

ABSTRACT: We examine the effect of isovalent substitutions and co-doping on the ionic dielectric constant of paraelectric titanates (perovskite, Ruddlesden-Popper phases, and rutile) using density functional perturbation theory. Substitutions increase the ionic dielectric constant of the prototype structures, and new dynamically stable structures with ε_ion ~ 10²-10⁴ are reported and analyzed. The boosting of ionic permittivity is attributed to local defect-induced strain, and maximum Ti-O bond length is proposed as a descriptor. The Ti-O phonon mode that is responsible for the large dielectric constant can be tuned by a local strain and symmetry lowering from substitutions. Our findings help explain the recently observed colossal permittivity in co-doped rutile, attr

SUBMITTER: Kutana A 

PROVIDER: S-EPMC9992386 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature