抄録
Recent progress on multilayer ceramic capacitors (MLCCs) with Ni electrodes is reviewed from the viewpoint of non-reducible dielectric materials. Using intermediate ionic size rare-earth ions (Dy, Ho, Er, Y) doped BaTiO3 (BT) based dielectrics, highly reliable Ni-MLCCs with very thin layer about 1 μm have been developed. The effect of site occupancy of rare-earth ions in BT on the electrical properties and microstructure was studied systematically. It appears that the intermediate ionic size rare-earth ions occupy both A- and B-site in BT lattice and effectively control the donor/acceptor dopant ratio and microstructural evolution. The effect of raw BT powder characteristics, such as particle size and crystallinity on the microstructure as well as the electrical properties of MLCC with ultra thin active layers was also investigated. The dielectric constant at room temperature drastically decreased for the grain size of less than 200 nm. The MLCC samples using raw BT with high tetragonality (c/a) showed high dielectric constant and stable temperature characteristics. The synthesis of fine-grained and high crystalline BT particles by solid state process is also presented.
