β-radiation-induced conductivity of poly(2-vinylpyridine)-cobalt complex

The electric conductivity of poly(2-vinylpyridine) increases by several orders of magnitude on its complexation with certain metal salts, notably cobalt chloride. Measurements of the change in conductivity of the poly(2-vinylpyridine)-cobalt (Co-P2VP) complex when exposed to radiation are presented. Pellets of Co-P2VP were irradiated with 1MeV β-particles at room temperature over a dose range from 0.795 x 108 e cm-2 to 18 x 108 e cm-2. Current versus voltage measurements were made on these pellets over the range 0-300 V. The conclusion drawn from the results is that radiation-induced conductivity is controlled by free charges through the Onsager mechanism. The free charges result from the disordering of the polymer structure under irradiation. While sustaining the conductivity, free charges also tend to limit it through recombination. Traps existing in the material at the onset of irradiation are neutral. Trap filling, and thereafter recombination, limit the current and give rise to an exponential relationship between current and dose. The results show an increase in current up to a dose of 11.7 x 108 e cm-2 followed by a decrease with dose. (1 table, 2 figures, 10 references). (UK)