New precise determination of the high temperature unusual temperature dependent thermopower of liquid divalent cadmium and zinc

We do not know any precise measurement of the absolute thermopower (ATP) of liquid cadmium and zinc at high temperatures. For liquid cadmium, there ar e, in the literature, apparent contradictory results. Bath and Kliem and No rth and Wagner observed that the ATP increases with temperature between 350 degrees C and 650 degrees C, but Bradley observed the opposite behaviour b etween 600 degrees C and 750 degrees C. In this work we measured accurately the absolute thermopower of liquid cadmium from the melting point up to 90 0 degrees C. We find a maximum around 520 degrees C, and then the thermopow er decreases down to a surprising negative value. To our knowledge, it is t he first time that such an unusual behaviour is reported. Nevertheless, it is qualitatively consistent with all the authors mentioned and the apparent contradictory results should only be due to the different temperature rang es of measurements. Using the ATP expression from the Faber-Ziman formalism , we can fit very well the experimental absolute thermopower versus tempera ture curve with only one adjustable parameter. For this, we have considered that the temperature dependence of the ATP is dominated by the resistivity , and we have introduced the experimental resistivity temperature dependenc e in the ATP expression. The very good fitting quality demonstrates that ou r hypothesis is consistent. In contrast, the liquid zinc ATP only increases with temperature. Nevertheless, near 1100 degrees C, the highest temperatu re achieved, it shows saturation that may be an indication of a decrease at higher temperature. The same type of fitting gives also quite good results .