Elektrischer Kondensator, dessen Dielektrikum aus einem Koerper aus reduzierter Keramik mit oxydierten Oberflaechenschichten besteht

摘要

Up to 12% (but preferably 2% to 6%) by weight of bismuth oxide is added to barium titanate before reduction of the mixture to dense sintered sheet form. The sheet surfaces are then re-oxidized to produce a dielectric suitable for capacitors. Alkaline-earth zirconates and/or stannates may be added to the mixture. In one example a mixture of 83% by weight of Ba Ti O3, 13%-Ca Zr O3 and the remainder Bi2O3 is pressed into small plates which are sintered in an oxidizing atmosphere at about 1400 DEG C., then reduced at 1200 DEG C.-1300 DEG C. and subsequently reoxidized by heating in air, the last mentioned process preferably being combined with the burning in of the capacitor electrodes. The bismuth oxide may be added to the re-oxidised surface layer only.