SEMICONDUCTOR CERAMIC AND POSITIVE TEMPERATURE COEFFICIENT THERMISTOR

文件类型：PDF文档
文件大小：571K
A semiconductor ceramic of the present invention includes a BaTiO 3 -based composition, as a main component, having a perovskite structure represented by general formula A m BO 3 . Part of Ba constituting an A site is replaced with an alkali metal element, Bi, Ca, Sr, and a rare-earth element. Assuming that the molar ratio of the Ca is x and the molar ratio of the Sr is y, the contents of the Ca and the Sr when the total number of moles of the elements constituting the A site is 1 mole are determined so as to satisfy 0.05 ‰¤ x ‰¤ 0.20, 0.02 ‰¤ y ‰¤ 0.12, and 2x + 5y ‰¤ 0.7. A PTC thermistor includes a component body 1 formed of the semiconductor ceramic. Accordingly, even when an alkali metal element and Bi are contained, there is provided a lead-free semiconductor ceramic with high reliability in which the discoloration of a surface is not caused and the degradation of resistance over time can be suppressed even after the application of an electric current for a long time.