The influence of Ar þ implantation induced disordering in the surface layers of the CR-39 polymer on its optical properties and surface hardness has been studied. The specimens were implanted at 130 keV to the doses of 5 Â 10 14 , 1 Â 10 15 , 1 Â 10 16 Ar þ cm À2 . The structural behavior of the pre-and postimplanted specimens was investigated using UV-Visible, Raman, and x-ray diffraction techniques. Formation of disordered graphitelike structures in the implanted layers of polycarbonate has been observed using Raman and UV-Visible spectroscopy. A significant increase in the value of disorder content (Urbach energy) from 0.77 eV to 1.48 eV and a continuous decline in optical bandgap (from 3.43 eV to 2.32 eV) with increasing implantation dose have been observed. This decrease in optical bandgap has been found to have linear dependence on the increase in the Urbach energy, which points toward the formation of disordered structures in the implanted layers of CR-39 polymer. Further, Knoop microhardness is found to be enhanced by a factor of 7 (at a load of 9.8 mN) after implantation. The possible correlation of the increase in Knoop surface hardness with the changes observed as a result of implantation has been established and discussed.
In this paper, we present the analysis of the dielectric (dielectric constant, dielectric loss, a.c. conductivity) and electrical properties (I–V characteristics) of pristine and nitrogen ion implanted polycarbonate. The samples of polycarbonate were implanted with 100 keV N+ ions with fluence ranging from 1 × 1015 to 1 × 1017 ions cm−2. The dielectric measurements of these samples were performed in the frequency range of 100 kHz to 100 MHz. It has been observed that dielectric constant decreases whereas dielectric loss and a.c. conductivity increases with increasing ion fluence. An analysis of real and imaginary parts of dielectric permittivity has been elucidated using Cole-Cole plot of the complex permittivity. With the help of Cole-Cole plot, we determined the values of static dielectric constant (εs), optical dielectric constant (ε∞), spreading factor (α), average relaxation time (τ0), and molecular relaxation time (τ). The I–V characteristics were studied using Keithley (6517) electrometer. The electrical conduction behaviour of pristine and implanted polycarbonate specimens has been explained using various models of conduction.
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