Space charge polarization modulated instability of low frequency permittivity in CaCu₃Ti₄O₁₂ ceramics

A low frequency dielectric relaxation process of CaCu₃Ti₄O₁₂ ceramics, which is generally overlapped by dc conduction in traditional dielectric spectra, is detected and clarified based on an improved analytical methodology in this letter. This relaxation process remarkably contributes to instability of low frequency permittivity and it clearly demonstrates the correlation between charge migration and space charge polarization. It is revealed that conduction will be achieved if carriers migrate and combine in the electrodes, while space charge polarization will be achieved if carriers migrate to the electrodes without combination.