Mass Spectrometric Study of the Vaporization of LiF, NaF, and LiF–NaF Mixtures

Abstract

Vapors effusing from Knudsen cells containing LiF, NaF, and LiF–NaF mixtures have been analyzed mass spectrometrically. The over‐all temperature range studied is between 900 and 1150°K. Monomers, dimers, and trimers of LiF and NaF are observed. The LiF system has the higher concentration of dimers and trimers. In the LiF–NaF system at 50 mole percent LiF the mixed dimer, LiNaF₂, is the major polymeric vapor species. Thermochemical data for LiF(g), NaF(g), Li₂F₂(g), Na₂F₂(g) and Li₃F₃(g) have been obtained. For the reaction Li₂F₂(g)+Na₂F₂(g)=2LiNaF₂(g), ΔH° is approximately zero.