A GdBa2Cu3O7-delta ceramic rod with a core of Cd2BaCuO5 was prepared by dip coating. A hot spot appeared in the rod when a voltage exceeding a certain value was applied at room temperature. Moreover, the hot spot was broken into two when the voltage was increased further. A mechanism for the appearance of the double hot spots is discussed from the viewpoint of the change of resistance in the hot spot.
Keywords: dip coating; complex oxide; oxygen sensor; hot spot