Enhancement of p -type conductivity in nanocrystalline BaTi O3 ceramics

Undoped BaTi O3 ceramic samples with an average grain size of ~35 nm were prepared and the electrical properties investigated. The defect structure is dominated by acceptor impurities; therefore, the conductivity of nanocrystalline BaTi O3 is of p -type. Comparing with microcrystalline BaTi O3, the conductivity of nanocrystalline BaTi O3 is about 1 to 2 orders of magnitude higher and the activation energy remarkably lower, which is ascribed to a greatly reduced oxidation enthalpy in nanocrystalline BaTi O3 (~0.3 versus ~0.92 eV for microcrystalline BaTi O3).