OAM-RC

Abstract

AC conductivity[σ(ω)], dielectric constant [ε' (ω)], tangent loss factor (tanδ = ε''/ε') and dielectric loss [ε'' (ω)] have been measured in pristine and 100 MeV Ag-ion (fluence; 1.8X1011 ions/cm2) irradiated 20 μm Poly (Vinylidene Fluoride) (PVDF) thin films in the temperature region 30°C -170 °C at different frequency ranging from 1kHz -1MHz. Dielectric conductivity [σ(ω)] was derived from the dielectric constant and loss tangent data in the frequency range 1kHz-1MHz. The frequency dependent ac conductivity described by Jonscher power law σ(ω) = A (ω)N , has been observed in the low temperature region where N<1 and decreases with increase in temperature for pristine PVDF. The ε' (ω) of pristine film in low temperature region shows week dependence on the temperature and show strong dependence of temperature at higher temperature region. Trapped charge carriers make a large contribution to the dielectric parameters at lower frequencies. The variation of ac conductivity for Ag-ion irradiated PVDF thin film with frequency also obeys Jonscher power law except a small deviation in the low frequency region. There is an overall increase in ε' (ω) in ion irradiated sample as compare to the pristine sample. This shows the dominance of interfacial polarization arising from the large number of radiation induced defect sites and free radicals. Two relaxations; the αc- and the αa- relaxations, appearing from high temperature side to low temperature side in the dielectric loss versus temperature spectrum have been observed in present investigation.

Keywords

PVDF, SHI, Dielectric constant, Dielectric loss, Tangent loss factor.

Citation

D. S. RANA, D. K. CHATURVEDI, J. K. QUAMARA, AC conductivity and dielectric constant/loss measurement in pristine and swift heavy 100 MeV Ag-ion irradiated poly (vinylidene fluoride) films, Optoelectronics and Advanced Materials - Rapid Communications, 4, 6, June 2010, pp.838-844 (2010).

Submitted at: May 26, 2010

Accepted at: June 16, 2010