Dielectric spectroscopy characterization of relaxation process in Ni/epoxy composites

Nickel (Ni)/epoxy composites with different Ni filler additions were prepared, and the dynamic dielectric properties of the composites were investigated using broadband dielectric spectroscopy spectrometer with the frequency range 1-107 Hz at the temperature of −20 to 200 °C. The dielectric properties as a function of temperature and frequency show three relaxation processes: (1) Maxwell interfacial polarization at low frequencies; (2) a primary α-relaxation process at near glass transition temperature (Tg); and (3) ionic conduction relaxation at the middle frequencies between 100 °C and 200 °C. Detailed studies of modulus spectrum suggest non-Debye type of relaxation mechanism for the composites. The Cole-Cole plots exhibit the contribution of filler concentration effect in the modulus characteristics of the Ni/epoxy composites. Alternating current (AC) conductivity and electric modulus studies support the hopping type of conduction in the composites, and frequency dependent AC conductivity data obey Jonscher's power law.