The effect of irradiation of polymeric sulphur nitride with neutrons and heavy ions

Abstract

Measurements are presented of the electrical conductivity along the chain axis of polymeric sulphur nitride, (SN) _x , for samples bombarded at 20 K with fast neutrons (∼1 MeV) and with fission fragments (∼100 MeV). Samples subjected to neutrons showed an increase in resistivity linear with dose, comparable to that seen in metals and characteristic of point defect formation. Damage is completely annealed out on warming to room temperature. The intrinsic resistivity of the defect centre is estimated to be ∼8000 μΩ.cm/at. %, a value close to that measured in an anisotropic semimetal such as bismuth. In contrast, heavy ion bombardment increased the resistivity more dramatically, and the damage caused is permanent. We consider that this type of damage, arising from local heating by the electronic excitation thermal spikes, is related to the fibrous, microcrystalline nature of (SN) _x perpendicular to the chain axis.