Origins of dielectric response and conductivity in (Bi1−xNdx)FeO3 multiferroic ceramics

The dielectric response and conductivity have been measured in (Bi1−xNdx)FeO3 (x = 0.0 and 0.05) ceramics as functions of temperature and frequency. A one-dimensional across-barrier model with intrinsic barriers, B (in temperature units), every lattice constant, a, and extrinsic barriers, B + Δ, every distance, d, is introduced to describe the dielectric response and conductivity. The across-barrier hopping is responsible for the high-temperature conductivity and step-like dielectric relaxation in the region of 500–800 K. Good qualitative fits of dielectric dispersion and conductivity are obtained with d = 20–30 nm, B = 8400–8700 K (∼0.72–0.75 eV), and Δ = 2500 K (∼0.215 eV). The resistivity plot of scaled ρ" versus ρ' indicates a contribution of grain boundaries or internal defects to the conductivity.