Nonlinear I–V behavior in colossal permittivity ceramic:(Nb+In)co-doped rutile TiO2

Abstract The new (Nb+In) co-doped TiO2 ceramics recently stimulated considerable attention due to their colossal permittivity (CP) (~100,000). In this research, the 3 mol% (Nb+In) co-doped TiO2 ceramics were synthesized by an standard solid-state reaction method. Phase structure was studied by XRD and Raman, which showed that all samples were in pure rutile phase. The elements distribution was tested by the SEM–EDS, indicating that the Nb and In ions were homogeneously distributed in the grain and grain boundary. Dielectric properties and I–V behavior analysis demonstrated that the ceramics may compose of semiconducting grains and insulating grain boundaries. The existence of CP and nonlinear I–V behavior in sample had been explained by an internal barrier layer capacitance (IBLC) model, which consists of n-type semiconductor grains and insulating grain boundaries.