Mass spectrometric studies at high temperatures: XVII. Sublimation and vapor pressures of Dy(III), Ho(III) and Er(III) fluorides

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Abstract

The sublimation and vapor pressures of DyF3, HoF3 and ErF3 were measured mass-spectrometrically and by semimicrobalance Knudsen studies. DyF3, HoF3, and ErF3 were established as the major vapor species over the respective solid 01 molten trifluorides by mass-spectrometric work. The results are represented for DyF3 by: log Psub. (atm) = − (2.325 ± 0.031) × 104T + 10.720 ± 0.229log Pvap. (atm) = − (1.842 ± 0.032) × 104T + 7.538 ± 0.209, for HoF3 by log Psub. (atm) = − (2.309 ± 0.033) × 104T + 10.650 ± 0.245log Pvap. (atm) = − (1.847 ± 0.048) × 104T + 7.333 ± 0.330, and for ErF3, by log Psub. (atm) = − (2.339 ± 0.054) × 104T + 10.680 ± 0.391log P vap. (atm) = − (1.930 ± 0.027) × 104T + 7.777 ± 0.186 where errors noted are standard deviations from the least-squares fits. The heats of sublimation and vaporization are : for DyF3ΔHsub. (1356°K) = 106.4 ± 1.5 kcal mole−1ΔHvap. (1523°K) = 84.3 ± 1.5 kcal mole−1 for HoF3ΔHsub. (1366°K) = 105.6 ± 1.5 kcal mole−1ΔHvap. (1465°K) = 84.5 ± 2.2 kcal mole−1 for ErF3ΔHsub. (1373°K) = 107.0 ± 2.5 kcal mole−1ΔHvap. (1461°K) = 88.3 ± 1.2 kcal mole−1

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