Giant dielectric permittivity observed in CaCu3Ti4O12/(Li,Ti)-doped NiO composites

The giant values of the dielectric permittivity as high as epsilon(')similar to 10(5) at various frequencies (f=100 kHz-1 MHz) over a broad temperature range of -50-190 degrees C have been observed in polycrystalline CaCu3Ti4O12 ceramics that are reinforced with small amount of Li0.3Ti0.02Ni0.68O nanoparticles of 39 nm. This enormous dielectric permittivity is even higher than that of CaCu3Ti4O12 single crystals. The dielectric behavior of CaCu3Ti4O12 and CaCu3Ti4O12-Li0.3Ti0.02Ni0.68O composites exhibits Debye-like relaxation which can be interpreted based on Maxwell-Wagner model. The dielectric dispersion of the composites was discussed based on internal boundary layer capacitor effect. (C) 2007 American Institute of Physics.