Colossal permittivity behavior and its origin in rutile (Mg(1/3)Ta(2/3))(x)Ti(1-x)O(2)

This work investigates the synthesis, chemical composition, defect structures and associated dielectric properties of (Mg(2+), Ta(5+)) co-doped rutile TiO(2) polycrystalline ceramics with nominal compositions of (Mg(2+) (1/3)Ta(5+) (2/3))(x)Ti(1−x)O(2). Colossal permittivity (>7000) with a low dielectric loss (e.g. 0.002 at 1 kHz) across a broad frequency/temperature range can be achieved at x = 0.5% after careful optimization of process conditions. Both experimental and theoretical evidence indicates such a colossal permittivity and low dielectric loss intrinsically originate from the intragrain polarization that links to the electron-pinned [Formula: see text] defect clusters with a specific configuration, different from the defect cluster form previously reported in tri-/pent-valent ion co-doped rutile TiO(2). This work extends the research on colossal permittivity and defect formation to bi-/penta-valent ion co-doped rutile TiO(2) and elucidates a likely defect cluster model for this system. We therefore believe these results will benefit further development of colossal permittivity materials and advance the understanding of defect chemistry in solids.