Barium titanate based semiconducting ceramic material

摘要

A semiconducting ceramic material containing BaTiOSB3/SB has a high breakdown voltage. Above the Curie temperature, the ceramic has a positive temperature coefficient of resistance in a first temperature range, and a negative temperature coefficient of resistance in a second, higher temperature range. A boundary temperature defined at the boundary between a first temperature range and a second temperature range is 180{C or more (e.g. 370{C) higher than Curie temperature. The semiconducting ceramic is prepared by mixing a BaTiOSB3/SB source, a material imparting a semiconducting property to BaTiOSB3/SB, SiOSB2/SB and optionally Mn to form a mixture, calcining the mixture, mixing with a organic binder, compacting, firing the compact in an NSB2/SB/HSB2/SB atmosphere at a temperature lower than a temperature at which the mixture is completely sintered, and re-oxidising the fired compact in air. Preferably samarium is added to impart semiconductivity to the barium titanate. Preferably the mole ratio of SiOSB2/SB to BaTiOSB3/SB is 0.0005 and the mole ratio of Mn to BaTiOSB3/SB is in the range of 0 to 0.0001. The semiconducting ceramic material may be used in electronic components having internal electrodes where the semiconducting material and the internal electrodes are alternately superposed on one another.