Impedance spectroscopy of Ba ₄Ti ₁₃O ₃₀ film prepared by laser chemical vapor deposition

The impedance and electrical conductivity of Ba ₄Ti ₁₃O ₃₀ film prepared by laser chemical vapor deposition were investigated as functions of temperature (300-1073 K) and frequency (10 ²-10 ⁷ Hz). The impedance response was resolved into two contributions, which were associated with the grains (R _gC _g) and grain boundaries (R _gbC _gb).With increasing temperature, both R and C decreased. R _gb was much higher than R _g and C _g were close to C _gb. Below 876 K, a step-like behavior was observed in the ac conductivity plots as functions of frequency due to two dispersion regions. The low-frequency dispersion was associated with grain boundaries and the high-frequency one corresponded to grains. The activation energies of grain conduction (E _g) and grain boundary conduction (E _gb) were 0.20 and 1.49 eV, respectively, which indicated that the relaxation process in grains arose from hopping electron and that in grain boundaries from the diffusion of oxygen vacancies.