Preparation of mixed phosphates in molten alkali metal nitrates

Mixed phosphates of alkali metals and main or transition group metals were obtained from the reactions of different starting salts of metals (nitrates, chlorides) and ammonium hydrogen monophosphate at 673-823 Ii in the alkali metal nitrate fluxes. The products obtained include submicrometer dispersions of known commercially important compounds, among which are KTiOPO4 (KTP), a number of ABPO(4) phases (where A stands for alkali metal; B, bivalent transition or main group metal), as well as various substituted phases, derived from the NASICON NaZr2(PO4)(3) and lamellar zirconium phosphate structure. Sometimes novel mixed phosphates were formed, such as those of sodium and nickel or cobalt, for which stoichiometric composition and/or elementary cell parameters have been established. The dependence of composition of solid products on the nature of reacting species and reaction conditions was discussed. Possible extensions of method by means of chemical modifications with admixtures of nitrite and fluoride species were considered and illustrated by several examples.