Mass Spectrometric Studies at High Temperatures. II. The Sublimation Pressures of Magnesium, Strontium, and Barium Fluorides

A mass spectrometer has been employed to measure the sublimation pressures and heats of sublimation for MgF2 over the range 1241° to 1492°K; for SrF2 over the range 1207° to 1563°K; and for BaF2 from 1232° to 1505°K. For MgF2 the results are represented by logPatm=−[(88.3±0.9)/45.76]104T−1+8.53±0.2;for SrF2 by logPatm=−[(99.3±0.7)/45.76]104T−1+8.716±0.01;and for BaF2 the equation is logPatm=−[(85.1±0.9)/45.76]104T−1+7.659±0.01.The errors quoted are the standard deviations from the least-squares fitted lines. The heat of sublimation of MgF2 at 1366°K is 88.3±2.5 kcal mole—1 while the heats of sublimation at 298°K are 103.7±2.5 kcal mole—1 for SrF2 and 92.3±2.0 kcal mole—1 for BaF2.