Wenn Metall schmilzt, sind auch die positiv geladenen Atome beweglich. Steigt der elektrische Widerstand dann weiter, steigt er langsamer oder sinkt er?
Nein, die Protonen sind weiterhin im Atomkern festgehalten. Generell steigt der Widerstand in Metallen mit der Temperatur, da die Atome sich stärker bewegen und die freien Elektronen daher mehr streuen. Je nach Metall ist der Widerstand in der flüssigen Phase höher oder niedriger als in der festen Phase.
The Electric Resistivity of the Metals in the Molten State
Abstract The temperature dependence of the resistivity for various kinds of molten metals, Ag, Cd, Zn, In, Sn, Pb, Bi and Sb was measured over wide ranges of temperatures by means of Roll and Motz’s electrodeless method and discussed theoretically. The temperature coefficient of the resistivity of alkalli metals, which was measured by Mac Donald and others, is known to be somewhat larger in the liquid than those in the solid. It is, however, generally smaller in the liquid than in the solid for other metals. A theoretical investigation for the temperature dependence of the resistivity was carried out under the assumption that the valence electrons of atoms in metals behave as the free electrons in a random potential field of ions. It was found that the resistivity of molten metals was given by the sum of the residual resistivity ρ 0 caused by the completely random arrangement of ions and the additive resistivity ρ T which arises from the density fluctuation due to the thermal motion of the ions. The temperature dependence of the resistivity of molten metals is attributed by the term ρ T due to the density fluctuation, while the density fluctuation is directly proportional to the compressibility κ, so that the magnitude of κ is a main factor for the temperature coefficient of the resistivity. These theoretical results are in good agreement with the observed values and the larger temperature coefficient for alkali metals is due to their compressibilities than those of other metals.
https://www.jstage.jst.go.jp/article/matertrans1960/3/1/3_1_30/_article