Study of segregation process of impurities in molten tellurium after one pass of three conjoint zones in zone refining

Zone-melting process provides a great amount of knowledge about parameters governing the process of optimal purification for tellurium, especially the effective segregation coefficients Keff. A series of 13 values of Keff were determined after one pass n=1n=1 and one molten zone N=1N=1 at the same conditions of temperature T and interface velocity V. These values are used to extract a mathematical model of the distribution concentration Ψ3 (x)=CS/C0 for n=1n=1 and N=3N=3, treated 13 times for 13 impurities. After 3 passes of tellurium molten zone, a decrease of the concentration of the residual impurities concentrations was registered, and a better fitting between experimental points CS/C0 with the extracted theoretical model was also observed. Besides, the effect of high conductivity of liquid tellurium was studied; leading to a decrease of the driving forces, therefore the ultimate distribution was enhanced. Under our experimental conditions, we propose N=3N=3 as maximum number of molten zones needed to achieve an ultimate purification of tellurium with good efficiency.