Preparation of “NaREF4” phases from the sodium nitrate melt

Abstract Preparation of “NaREF 4 ” compounds (RE = La-Lu, Y) from rare earth nitrates dissolved in molten NaNO 3 has been studied at 350°C. Two-fold excess of sodium fluoride (NaF) was used as fluorinating agent. Hexagonal NaREF 4 (RE = Pr-Lu, Y) phases isotypic with β-NaYF 4 have been prepared. A mixture of CeF 3 and NaCeF 4 was obtained in cerium system, while only LaF 3 phase was formed in lanthanum system.