| 초록 |
Electrical properties of non-stoichiometric BaBiO3-δ have been of interest by different scientific fields covering subjects such as superconductivity, topological insulator, charge ordering, photocatalysis and high temperature mixed-ionic-electronic conduction. Electronic structure, conduction mechanism, oxygen non-stoichiometry and phase transitions are supposed to be closely related but overall understanding is not yet achieved. In this work, BaBiO3 bulk samples were prepared from BaCO3 and Bi2O3 using solid state reaction method. The precursors were mixed and calcined at 720°C for 10h. The calcined powder was then pressed isostatically into pellets which were sintered at 800°C for 20h. X-ray diffraction result confirmed that the samples were constituted of perovskite single-phase. AC response was measured over the wide temperature range using an electrical furnace, a heating stage, and a cryostat. The dielectric and conductive properties indicate the characteristic transitions at the temperatures some of which correspond to the known structural phase transitions. Oxygen atmosphere dependence was studied. Detailed examination of AC behavior in different temperature regions is expected to provide a valuable insight into conduction mechanism in relation to the phase transition and oxygen nonstoichiometry. |
