Abschätzung von Zustandsdichten des Silbers in a-Silber-Mischkristallen mit Gallium, Indium, Germanium und Zinn auf Grund thermodynamischer Untersuchungen mittels galvanischer Festkörperzellen / An estimation of densities of state of silver in a-solid solutions of silver with gallium, indium, germanium and tin based on thermodynamic investigations by means of solid state galvanic cells

Abstract

Abstract The partial free enthalpies of formation of the binary a-solid solutions of silver with gallium, indium, germanium and tin were determined at 1000 °K from the EMF of suitable solid state galvanic cells. A further evaluation of the results taking into account known enthalpies of for­mation yielded the complete partial and integral excess functions of these solid solutions. An analysis of the difference of the excess values of the partial free enthalpies of formation of the components showed that the lattice distortion, due to differences in atomic radii of the solid solutions studied, is not very significant. Differences in the structure between the solid solution and its components can be clearly noted only in the case of the silver-germanium solid solutions. The energetics of the alloys are determined principally by the filling of the 5s1 conduction band of the silver by the electrons contributed by higher-valent constituents. From the thermodynamic results the density of state of the conduction band of the silver was estimated to be smaller than 0.31 electr. per atom and eV. The density of state increases with increasing concentration of the alloying component; this can be explained by a change in the Fermi surface in the silver host lattice