Electrical properties in semiconducting BaTiOィイD23ィエD2 bicrystals

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BaTiOィイD23ィエD2, Which is often used as based materials for electroceramics, exhibits semiconduction when it is doped with cations whose valence is large than host cations' valence. In general, most of electroceramics are utilized for practical use as in polycrystals and their electrical properties is often closely related to their grain boundary phenomena. Therefore, it must be necessary to investigate the electrical properties directly at single grain boundaries. In this study, BaTiOィイD23ィエD2 bicrystals were fabricated and then their electrical properties were examined. The following results could be obtained.(1) It was succeeded in construction of the technique for controlling the abnormal grain growth in BaTiOィイD23ィエD2 by changing A/B-site ratio. Coarse-grained structure with a grain size of about 1mm could be obtained.(2) It was found that the electrical properties in BaTiOィイD23ィエD2 bicrystal closely depend on the grain orientation relationship. The magnitude of Positive temperature coefficient of resistivity effect decerases with an increase in the coherency at grain boundaries.(3) The similar tendency could be obtained also in SrTiOィイD23ィエD2 bicrystal, which has the same lattice structure and similar electrical properties.