New materials and processes for the manufacturing of ceramics presenting colossal values of permittivity

Due to their potential application in microelectronics, high dielectric constant materials, (epsiv\´_r > 10 000), are very attractive. Among them, there has been recently a considerable interest for various perovskite oxides like calcium copper titanate CaCu₃Ti₄O₁₂ (CCT hereafter) or lanthanum doped barium titanate (Bai_1-xLa_xTi_1-x/4O₃ (0 les x les 0.138) (La doped BT)). These materials may exhibit, when processed in a particular way, a so called "giant"or "colossal" permittivity value (larger than 300 000) with unusual temperature dependence. In this paper, we report the very last results obtained on these two different types of materials.