Intergranular insulation type polycrystalline ceramic semiconductive composition
AssigneesSony Corporation, Taiyo Yuden Co., Ltd.
InventorsYasunori Takahashi, Nobutatsu Yamaoka, Yoshifumi Yamaoka, Shuichi Kakubari
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Abstract
An intergranular insulation type semiconductive ceramic composition comprising a major proportion of strontium titanate (SrTiO.sub.3), a minor amount of niobium oxide (Nb.sub.2 O.sub.5) or tantalum oxide (Ta.sub.2 O.sub.5), a minor amount of either germanium oxide (GeO.sub.2) or zinc oxide (ZnO) and having diffused therein either bismuth oxide (Bi.sub.2 O.sub.3) or a mixture of bismuth oxide, lead oxide (PbO) and boric oxide (B.sub.2 O.sub.3). The material is especially useful as a capacitor.
Claims5
An intergranular insulation type semiconductive ceramic composition comprising from 90.68 to 99.88% by weight of polycrystalline SrTiO.sub.3, from 0.07 to 5.32% by weight of either Nb.sub.2 O.sub.5 or Ta.sub.2 O.sub.5, from 0.05 to 4.00% by weight of either GeO.sub.2 or ZnO, and having diffused therein either Bi.sub.2 O.sub.3 or a mixture of Bi.sub.2 O.sub.3, PbO, and B.sub.2 O.sub.3, the diffused material providing a substantially uniform insulating layer about the grain boundaries of the polycrystalline SrTiO.sub.3.
A method of making an intergranular insulation type semiconductor ceramic composition which comprises mixing a major amount of SrTiO.sub.3 with a minor amount of Nb.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 and a minor amount of GeO.sub.2 or ZnO, molding the resulting mixture and sintering the same in a slightly reducing atmosphere to produce a polycrystalline ceramic, and thereafter diffusing therein Bi.sub.2 O.sub.3 or a mixture of Bi.sub.2 O.sub.3, PbO, and B.sub.2 O.sub.3 to insulate the grain boundaries of said ceramic.
Dependencies are inferred from the claim text.