The abnormal changes of electrical resistivity in liquid Pb-In alloys

Electrical resistivity of liquid lead and indium (Pb-In) alloys with different compositions has been measured using the four-probe method in a large temperature range. Marked turning points on each resistivity-temperature (p-T) curve of the liquid Pb-In alloys can be observed far above the liquidus. The unusual variation of the resistivity of Pb-In melts suggests a structural transition of these melts, for resistivity is a sensitive parameter to the structure. Moreover, the DSC experiment of Pb-In melts supports the existence of a liquid-liquid (L-L) structure transition in Pb-In melts. Such a L-L structural transition can be described in terms of the gradual disappearance of atomic bonds corresponding to the crystal structure and/or to a reduction of the size of pre-formed atomic clusters. This implies an increase of disorder in the high temperature melts. The transition temperatures depend on the composition of Pb-In melts and the onset transition temperatures of the intermediate phase (alpha) Pb-63%In and Pb-70.6%In melts are higher than that of other compositions.