Ion Exchange in Fused Salts. Iii. The Cation Exchange Characteristics of Some Borate, Borosilicate, and Borophosphate Glasses in Fused Sodium Nitrate

摘要

Six glasses, comprised of two alkali borates, two salt-loaded alkali borates, one low-silica borosilicate, and one borophosphate, were prepared and tested as ion exchangers for use with fused-salt solvents. These high-alkali borate glasses, including the salt-loaded ones, showed excellent selectivity among Cs, Na, Sr, Ba, and Eu in molten NaNO3, and appear to be more generally effective as ion exchangers in fused salts than any material previously tested. Inclusion of NaCl to the limit of its solubility in alkali borate glass greatly improved the rate of ion diffusion in the glass, thus removing the major drawback of glasses as ion exchangers. Inclusion of Na2SO4 did not have the same beneficial effect as that of NaCl. The borosilicate and borophosphate glasses tested did not show as good ion-exchange characteristics as did the pure alkali borates. High-alkali borate glasses showed selectivity for cations in the order of increasing field strength of the cation. The selectivity behavior provides information about the nature of the ion-exchange process in fused salts.