Ionic mobilities in selected fused salt systems

Transport numbers were determined in the pure fused salts LiNO/sub 3/, NaNO/sub 3/, KNO/sub 3/, and AgNO/sub 3/ by measuring the volume changes of the material in the electrode compartments which took place during electrolysis of the melt. Transport numbers in the two binary fused salt systems AgNO/sub 3/- NaNO/sub 3/ and AgNO/sub 3/- KNO/sub 3/ were determined by measuring the volume changes accompanying electrolysis and the concentration changes accompanying electrolysis. The transport numbers of the pure fused salts were found to agree with a radius fraction expression which implied that the mobility of an ion moving through a melt is inversely proportional to its size. It is pointed out that this equation failed for other fused salts, so, factors other than the size must also affect the mobility of the ions in a fused salt. The variation with composition of the cation mobilities in the binary systems studied is discussed in terms of ordered and disordered regions in the melt. (auth)