Purification of praseodymium to 4N5+ purity

• The average distillation rate of Pr was found to be ∼1.266 × 10−4 g cm−2 s−1 at the distillation temperature of 1700 °C.
• We study the relationships within distillation rate, mean free path and purity.
• The relation between the contents of non-metallic impurities and atomic voids was studied.

This paper was aimed at purifying praseodymium by vacuum distillation under two fractions and the purification process of praseodymium was studied. The detailed analysis of purified Pr was obtained by glow discharge mass spectrometry (GDMS) for 35 major impurity elements. High vapour pressure impurities in praseodymium melt, namely Mg, Al, Cr, Mn, Cu, Zn, Pb, Sm, Dy, Ho and Er were obviously reduced after the first distillation carried out at 1300–1400 °C for 4–6 h. The crucible impurity W was drastically reduced, from 209 ppmw to <0.05 ppmw, in the distilled praseodymium at a distillation temperature of ∼1700 °C under a dynamic vacuum of ∼2.0 × 10−4 Pa. According to the actual experimental conditions, the average distillation rate was found to be ∼1.266 × 10−4 g cm−2 s−1.

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