We note that partial structure factors of Cs and K in FLiNaK are di↵erent from binary salts, such as CsF or KF, which are structurally similar to NaCl. In binary salts, the anionanion and cation-cation correlations are in approximately in antiphase to anion-cation; such behavior is very common for cations from Li to Cs and for both Cl and F anions. In particular for Cs and K, previous measurements of CsCl and KCl showed this behavior clearly. This is in contrast to the results shown in Fig. .