Stepwise chlorination–chemical vapor transport reaction for rare earth oxide mixtures Gd 2O 3–Tb 4O 7, Tb 4O 7–Dy 2O 3 and Dy 2O 3–Ho 2O 3

Abstract

Stepwise chlorination–chemical vapor transport (SC–CVT) reaction has been investigated for the rare earth oxide mixtures Gd 2O 3–Tb 4O 7, Tb 4O 7–Dy 2O 3 and Dy 2O 3–Ho 2O 3 mediated by vapor complexes LnAl n Cl 3 n+3 (where Ln=rare earth elements). The results show selective deposition of lighter elements at higher temperatures. The separation factors are 5.84 for Gd/Tb, 3.72 for Tb/Dy and 3.13 for Ho/Dy when using CO as the CVT carrier gas. A combination of enhanced separation factor with reduced total transport yield is also observed for the Tb 4O 7–Dy 2O 3 system when using argon as the CVT carrier gas.