Dielectric behaviour of pure and nickel-doped cellulose acetate films

Abstract

Pure and Ni (0·05%, 0·1% and 0·15%)-doped cellulose acetate (CA) films were formed on well-cleaned glass substrates using a solution growth technique. Metal–insulator–metal (MIM) sandwich structures of thin film capacitors were fabricated. Dielectric studies were carried out in the frequency range 1kHz to 10MHz in the temperature range 303–450K. The variation of capacitance and dielectric loss with temperature were studied at various frequencies. The variation of dielectric constants (ε′ and ε″) with frequency and temperature is discussed. An increase in capacitance with temperature was observed and this may be due to the chaotic oscillations of molecules in the polymer matrix. β (at lower temperature) and α (at higher temperature) relaxation loss peaks were observed. Doping results in the formation of charge transfer complexes/molecular aggregates in the polymer, which cause the shift of Cmax value and the β and α relaxation loss peaks towards higher temperature. An appreciable dispersion of tan δ at lower frequency was noticed in all the samples studied. © 1998 SCI.