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Dielectric Behavior of Pure Polyacrylamide (PAM) Polymer films Doped-Vanadium Trichloride (VCl (3)) with Different Concentrations |
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PP: 37-45 |
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Author(s) |
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Khadijah M. AL-Mokhtar,
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Abstract |
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| Dielectric properties of pure Polyacrylamide (PAM) polymer films and doped Vanadium trichloride (VCl_3)
with different concentrations (4, 8, 12 % by weights), have been investigated. The films were prepared using solution
casting method, the dielectric capacitance and dielectric loss of the films were studied as functions of frequency and
temperature in the range (100 Hz - 100 KHz) and (290 - 390 K), respectively. Metal-insulator-metal (MIM) sandwich
structures of thin film capacitor were fabricated. The dielectric constant and dielectric loss were found to decrease upon
increasing frequency. The variation of capacitance and dielectric loss with temperatures were studied at various
frequencies. An increase in capacitance with temperature was observed and this may be due to the chaotic oscillations of
molecules in the polymer matrix. Two dielectric loss peaks were observed in the dielectric loss spectra and were identified
as β peak (at lower temperature) and α peak (at higher temperature). The β peak was attributed to the reorientation of
dipoles and the α -peak was attributed to the deformations accompanied by large changes in the directions or locations of
the dipoles. Doping results in the formation of charge transfer complexes/ molecular aggregates in the polymer, which
cause the shift of C_max value, also the β and α relaxation loss peaks towards higher temperature. An appreciable
dispersion of (tanδ) at lower frequency was noticed in all the samples studied. Impedance and A.C conductivity σa.c. of
the samples behaviors as function of frequency and temperature, for pure PAM and doped with different concentrations of
VCl_3 have been studied. The behavior suggests that the hopping mechanism might be playing an important role in the
conduction process in low-temperature regime. addition of Vanadium significantly improved the ionic conductivity. The
dispersion of tanδ at low frequencies (100Hz to 100 KHz) is found to be appreciable. Hence this material is more suitable
for using as good condensers in this frequency range. Also, the low value of ε and ε" at high frequencies suggest that the
prepared sample possess, suitable for using as nonlinear optical materials applications. |
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