Untersuchungen zum Leitungsmechanismus intermetallischer Verbindungen
According to the latest experiments of recent authors there are two distinct groups of intermetallic compounds: Those with a metallic behaviour and those with semiconducting properties. The measurement of the temperature dependence of the electrical conductivity, of the thermoelectric power and the Wiedemann-Franz-Lorenz ratio in this paper should shed some light on the boundary between these two groups. The authors show that in the system Zn-Sb the intermetallic compound ZnSb is a semiconductor. Its properties are discussed in detail in connection with the isomorphous semiconducting compound CdSb. In this way one obtains some insight in the structure of the chemical bond and the stability of these compounds. Careful observations of the electrical conductivity of alloys with a small deviation in the stoichiometric concentration, of the compound ZnSb prove that Zn3Sb2 also is in some modifications a real semiconductor. Investigations on the electrical properties of alloys in the system In-Bi allow us to conclude that InBi is a metallic compound. This behaviour is in contradiction to the well known InSb. The variation of the electrical properties when Bi-atoms are substituted for Sb-atoms in InSb is discussed in connection with the crystal structure. Similar experiments on Au2Bi and AuSb2 confirm the metallic character of both compounds. In contradiction to the statements on InSb-InBi there is no change in the electrical properties from a metallic to a semiconducting behaviour, although the relations between these compounds are very similar to those between the ZnS- and wurtzite-type-structure. The experiments and theoretical discussions confirm the fact that there is large number of physical parameters, as lattice-type, electronic configuration, electronegativity, chemical bond etc. which determine the nature of the electronic conduction. For a quantitative determination of the boundary between metallic and semiconducting compounds it is necessary to make further measurements in the present manner.