Effect of isoelectronic substitution of thermopower and resistivity of Hf1-XZrXTe5

The thermopower and resistance of single crystal pentatellurides in the series Hf_1-XZr_XTe₅(x=0, .25, .50, and 1.0) have been measured as a function of temperature from 10 K to 300 K. The results show that HfTe₅ and ZrTe₅ contain broad resistance peaks at a temperature, T_p, of 76 K and 147 K respectively, which are in agreement with previous measurements. Both compounds possess relatively large p-type thermopower (~+100 μV/K) which decreases rapidly through zero at a temperature T ₀ before changing to an equally large n-type thermopower (~-100 μV/K) at a temperature T<T₀. Through isoelectronic substitution of Zr for Hf (Hf_1-XZr_XTe₅), systematic shifts are observed in both T_p and T₀ as the Zr concentration increases. These ternary compounds retain the large p- and n-type thermopowers