Alkali chlorides cannot be used to prepare MNb2O6 (M=alkaline earth metal), and MCl2 is a candidate for molten salt. When the product phase is the MxM’1-xNb2O6 solid solution and the salt is MCl2-M’Cl2, then, an interchange reaction is possible. When Sr0.5Ba0.5Nb2O6 is prepared from SrCO3, BaCO3, and Nb2O5 using SrCl2-BaCl2, Sr–rich (Sr,Ba)Nb2O6 phase forms, for which the reaction BaO+SrCl2→BaCl2+SrO is responsible (Furubayashi & Kimura, 2011). Sr0.5Ba0.5Nb2O6 can be prepared by selecting the SrCl2 to BaCl2 ratio.