• A K Rakshit

      Articles written in Bulletin of Materials Science

    • Electrical properties of ion irradiated polypropylene films

      N L Singh Anita Sharma V Shrinet A K Rakshit D K Avasthi

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      The effect of high-energy (50 MeV) Li3+ ion beam irradiation on polypropylene (PP) film has been studied in the fluence range 2.4 × 1012-1.5 × 1014 ions/cm2. The a.c. electrical properties of PP films were measured in the frequency range from 0.05–100 kHz, and at temperature range between 30 and 140°C. This study indicates two peaks at 60°C and 120°C with comparatively high magnitudes. There is an exponential increase in conductivity with log of frequency and the effect is significant at higher fluences. The loss factor (tan 𝛿) vs frequency plot suggests that PP film based capacitors may be useful below 10 kHz. The capacitance is constant over a wide temperature range up to 130°C. FTIR spectra of the PP films before and after irradiation indicate that intensity of C–H stretching vibration at 2900 cm-1 is modified. The presence of many new peaks with the increase of fluence suggests the formation of alkanes and alkynes which might be responsible for the observed changes in the dielectric and electrical properties of PP films.

    • Analysis of organometallics dispersed polymer composite irradiated with oxygen ions

      N L Singh Anjum Qureshi A K Rakshit D K Avasthi

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      Thin films of polymethyl methacrylate (PMMA) were synthesized. Ferric oxalate was dispersed in PMMA films. These films were irradiated with 80 MeV O6+ ions at a fluence of 1 × 1011 ions/cm2. The radiation induced changes in electrical conductivity, Mössbauer parameter, microhardness and surface roughness were investigated. It is observed that hardness and electrical conductivity of the film increases with the concentration of dispersed ferric oxalate and also with the fluence. It indicates that ion beam irradiation promotes

      the metal to polymer bonding and

      convert the polymeric structure into hydrogen depleted carbon network.

      Thus irradiation makes the polymer harder and more conductive. Before irradiation, no Mössbauer absorption was observed. The irradiated sample showed Mössbauer absorption, which seems to indicate that there is significant interaction between the metal ion and polymer matrix. Atomic force microscopy shows that the average roughness (𝑅a) of the irradiated film is lower than the unirradiated one.

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