Behavior of impurity inclusions during vacuum distillation of tellurium

Experimental data are presented on the effect of the Te evaporation rate on the efficiency of the removal of submicron carbon particles (major impurit ies in Te, present in amounts from 10(6) to 5 x 10(8) cm(-3), depending on the purification procedure). By distilling a small amount of the melt, the effective separation coefficient was determined as a function of particle s ize. For 0.065- to 0.14-mum particles at a minimum evaporation rate of 3 x 10(-7) cm(3)/(cm(2) s), the separation coefficient lies in the range 9-100. As the evaporation rate increases to 2.5 x 10(-5) cm(3)/(cm(2) s), the sep aration coefficient drops to 2-8. Among the factors influencing the purific ation efficiency is the floating (inverse sedimentation) of submicron carbo n particles in molten Te, observed experimentally upon long-term holding.