Chemical and thermal stability of potassium nickel hexacyanoferrate(II)

The chemical and thermal stability of a nonstoichiometric compound K2-xNix/2[NiFe(CN)(6)]. nH(2)O (KNiFC) were examined in connection with distribution behavior for Cs+. The face-centered cubic (FCC) structure of KNiFC was stable even in the presence of 8 M HCl or 8 hr HNO3, and the samples treated with acids had high fid values for Cst above 10(4) cm(3)/g. This suggests high resistance of KNiFC to acids. For the KNiFC treated with HNO3, the lattice parameter (a) increased with increasing the concentration of HNO3 above 1 M. The FCC structure decomposed with NaOH concentrations above 1 M, probably due to the hydrolysis of constitutional elements. The thermal decomposition began above 250 degrees C and several steps of weight loss, due to evolution of gases, were observed up to 1,000 degrees C.