Resistivity of liquid K-Bi and Cs-Bi alloys

The authors have measured the electrical resistivity of liquid K-Bi and Cs-Bi alloys as a function of composition and temperature. In both alloy systems strong indications for chemical compound formation were found: in a large composition range the resistivity attains values that are characteristic for Mott's 'regime of diffusive motion'. In K-Bi the octet compound K 3 Bi dominates. In Cs-Bi at 550 degrees C the resistivity reaches a maximum of more than 4000 mu Omega cm at a composition of 40 at.% Bi (T=550 degrees C). This is explained by assuming that the Bi ions form poly-anions (Zintl ions), quite possibly chain fragments Bi n (n+2)- of variable length. The equi-atomic liquid alloy CsBi displays the unusual feature of a high resistivity (2000 mu Omega cm) combined with an almost negligible temperature dependence.