DIELECTRIC-PROPERTIES OF RARE-EARTH-OXIDE-DOPED BATIO3 CERAMICS FIRED IN REDUCING ATMOSPHERE

In order to gain an understanding of highly reliable electrical characteristics for the He-doped multilayer ceramic capacitors with Ni electrodes, dielectric properties of various rare-earth-oxide-doped BaTiO3 ceramics were studied. The smaller ionic radius rare-earth-oxide (Dy, Ho, Er)-doped samples showed lower resistivity in reducing atmosphere, but higher resistivity in oxidizing atmosphere at the cooling stage, compared with the larger-ion (La, Sm, Gd)-doped samples. Multilayer ceramic capacitors with Ni electrodes using the smaller-ion-doped materials showed smaller aging rate and longer lifetime. We developed Ni-electrode MLCs with X7R specification as 1 mu F in the 2125 type.