Dc electrical resistivity of reduced hexagonal BaTiO3

The dc electrical resistivity p of reduced hexagonal BaTiO3 polycrystal has been measured in a temperature range 40 K ∼ 380 K. At room temperature the p is about 0.4 ∼ 3 Ω cm. The p vs T curve drastically changes at around the hexagonal to orthorhombic phase transition temperature Ta ≃ 200 K; with increasing temperature, the p decreases below Ta, while above Ta it increases. The jump of the temperature derivative of p at around Ta is estimated as Δdp/dT ≃ 3 × 10-3 Ω cm/K. On the other hand, no anomaly is observed at around the ferroelectric phase transition temperature Tc ≃ 70 K. The resistivity increases rather steeply below about 100 K with decreasing temperature according to a polaronic mechanism: 1/p α T-3/2 exp(-E/kBT) where the global activation energy E is 0.06 eV.

Keywords:

• Electrical resistivity
• hexagonal BaTiO₃
• phase transition
• polaron