Preparation of NaREF4 phases from the sodium nitrate melt

Preparation of NaREF4 compounds (RE = La-Lu, Y) from rare earth nitrates dissolved in molten NaNO3 has been studied at 350 degrees C. Two-fold excess of sodium fluoride (NaF) was used as fluorinating agent. Hexagonal NaREF4 (RE = Pr-Lu, Y) phases isotypic with beta-NaYF 4 have been prepared. A mixture of CeF3 and NaCeF4 was obtained in cerium system, while only LaF3 phase was formed in lanthanum system.