Enhancement in gamma-ray induced decomposition of sodium and potassium nitrates by borate and cyanide additives

Gamma — radiolytic decomposition of sodium and potassium nitrates and its admixtures with respective cyanide and borate additives has been studied over a wide absorbed dose range from 675 to 500 kGy. The decomposition of nitrate increases with the nature and concentration of the additive in the admixture. The enhancement is more significant at >80 mol% of the additive.G(NO2−) values, calculated on the basis of electron fraction of the nitrate salt, decrease with increasing concentration of the nitrate. ESR spectral studies suggest the formation of radical species such as BO4 and BO32− etc, in borates whereas in case of cyanide additive FH centres are produced. The radical species and colour centres so produced may then transfer their energy to nitrate and cause enhancement in decomposition. A comparison with other oxyanion additives shows thatG(NO2−) values decrease in the order PO43−>B4O72−>SO42−>CO32−. Similarly, the nature of the cation also affects the decomposition.