Effect of Tellurium Doping on the Thermoelectric Properties of ZnSb

n-type tellurium doped ZnSb was prepared by direct melting at 923 K after which it was quenched in water within an evacuated quartz ampoule. All the ingots were heat treated at 723 K for 100 h. The resultant samples were characterized by Xray diffraction (XRD), differential thermal analysis (DTA) and by measurement of their Seebeck and Hall coefficients. XRD and DTA indicated that the solubility limit of tellurium in ZnSb was less than 3 at%. The samples with 0, 1 and 3 at% tellurium were p-type while those with 1.90 and 2.06 at% tellurium were n-type. These results indicated that n-type ZnSb samples can be obtained by the proper doping of tellurium. Excess doping with tellurium resulted in precipitation of the ZnTe phase and a change in conduction from n- to p-type. The maximum power factor for the 2.06 at% tellurium doped n-type sample was found to be 0.84 x 10(-3) Wm(-1) K-2 at 573 K.