Mass-Spectrometric Studies at High Temperatures. XI. The Sublimation Pressure of NdF3 and the Stabilities of Gaseous NdF2 and NdF

Abstract

A mass spectrometer has been used to study the sublimation of NdF3 and gaseous equilibria involving NdF3, NdF2, NdF, Nd, BaF, and Ba. The sublimation pressure of NdF3 is given by the equation logPatm=[−(1.873±0.025)×104/T]+8.03±0.17,where 1383°<T<1520°K. The heat of sublimation of NdF3 at 1448°K is 85.7±1.1 kcal mole−1. Studies of the equilibria among gaseous species over the mixtures Nd+BaF2 and Nd+NdF3 yielded the heats of atomization of NdF3(g) and NdF2(g) and the heat of dissociation of NdF(g). The standard heat of formation of NdF3(s) is −399±10 kcal mole−1.