Mass Spectrometric Study of Heats of Sublimation of Dysprosium, Samarium, Thulium, and Ytterbium

Abstract

The flux of atoms from a Knudsen‐type effusion cell has been studied by means of a mass spectrometer. The heat of sublimation was obtained from the dependence of the ion current upon the cell temperature by means of the Clausius‐Clapeyron equation. The method was used to obtain heat of sublimation values for dysprosium, samarium, thulium, and ytterbium. The results were: Dy, 69.3±0.6 kcal/mole for vaporization at 1215°K; Sm, 48.7±0.4 kcal/mole for vaporization at 811°K; Tm, 56.2±0.4 kcal/mole for vaporization at 937°K; and Yb, 39.5±0.5 kcal/mole for vaporization at 667°K.