The characteristics of chemical vapour transport and mutual separation for the scandium, yttrium and lanthanum mediated by the corresponding gaseous rare earth chloride complexes

The mutual separation characteristics of rare earths Sc, Y and La from the binary systems R2O3-R'O-2(3) (R: rare earths; R not equal R'=Sc, Y, La) by the chemical vapour transport (CVT) process mediated via RAlnCl3+3n or RKCl4 vapour complex under various different slopes of temperature gradient were investigated. More than 90% of ScCl3 with high purity (98.7% and 94.1%) was obtained from the binary systems Sc2O3-R2O3 (R=Y, La) by only one circle of CVT process under a low temperature gradient. The different CVT characteristics for ScCl3 from other rare earth chlorides RCl3 (R=Y, La) and large separation factors for the binary systems Sc2O3-R2O3 (R=Y, La) were discussed based on the difference in the ionic structure, electronic configuration between Sc and Y or La, and the different volatility of their pure chloride compounds. (C) 1998 Elsevier Science S.A.