Dielectric relaxation of (N(C2H5)4)2CoCl2Br2 nanocrystallites incorporated into the PMMA matrix

The dielectric properties of tetraethylammonium dibromo-dichloro-cobaltate (N(C₂H₅)₄)₂CoCl₂Br₂ (TEA-CBC) nanocrystallites incorporated into the polymethylmethacrylate (PMMA) matrix were investigated within the spectral range of 3 × 10⁵–3 × 10⁹ Hz in the temperature range of 90–300 K. The considerable difference of the dielectric spectra of the nanocomposite compared to the TEA-CBC crystal and to the pure PMMA matrix was observed. The phenomenon of the ‘negative capacity’ has been found in the considered material. Its dependence on the NC content was investigated. Temperature investigations of the dielectric permittivity for the TEA-CBC NC incorporated into the polymer PMMA matrices have shown the sharp-like resonance dependences of the imaginary part of the dielectric permittivity near 1.2 GHz. The intensity of the corresponding resonance peaks increase sub-linearly with increasing NC content. Taking into account the substantial growth of the imaginary part of the permittivity with increasing NC concentration, one can assume that the main contribution to the effect is given by the interface NC-PMMA regions. Additional experiments were performed to eliminate the influence of ‘geometry factor’.