FAST-NEUTRON IRRADIATION OF 1T AND H-2 TANTALUM DISULFIDES (TAS2)

Results of measurements of the electrical conductivity of 1T-TaS//2 and 2H-TaS//2 irradiated with fast neutrons are presented. A recent calculation by one of the authors permits an estimation to be made of the defect production rates in these binary compounds. The irradiation induced defects have large effects on the charge density waves' (CDW) contribution to the resistivity. In 1T-TaS//2 these defects qualitatively behave like substitutional impurities in doped samples but they are about two orders of magnitude more effective in changing the resistivity. 2H-TaS//2, in its low temperature phase, behaves under irradiation like a semi-metal. A qualitative explanation for the observed effects in both polytypes is proposed: The irradiation produces defects in the Van der Waals gaps which increase the 3-dimensional interaction between layers. These defects are more effective than the substitutional doping impurities in disturbing the CDW states.