Purification of tellurium up to 5N by vacuum distillation

This paper is aimed at purifying 3 N pure indigenous tellurium (Te) by vacuum distillation under a dynamic vacuum of ∼5 × 10− 4 torr. High vapour pressure impurities in tellurium melt, namely Cd, Zn, Mg and Pb were considerably reduced in the “first fraction” carried out at ∼500 °C for 20 min. The majority of impurities such as Fe, Ni, Cu, Sb, Mn, Ca, Al, Cr, Bi, Co and Si were drastically reduced, from 300 ppm to ∼5 ppm, in the distilled tellurium at a distillation temperature of 550 °C under dynamic vacuum. The impurity analysis carried out using inductively coupled plasma optical emission spectrometry (ICP-OES). Overall yield of up to 95% of 5 N pure tellurium was achieved at an average distillation rate of ∼8.6 × 10− 5 g cm− 2 s− 1 . The vacuum distilled material can be used as starting material for zone refining process to prepare ultra high pure (7 N) tellurium.