The work function of sputter‐formed Re‐1% Pt

摘要

High‐rate sputter deposition has been used to make free‐standing ribbons of Re‐1% Pt alloy. Changes in the work function and surface composition of the alloy as a function of temperature are reported. Segregation of Pt to the surface was accompanied by a decrease in work function indicating electron transfer from Pt to Re. When the Pt‐to‐Re ratio at the surface reached 0.26, the work function of the alloy was 1.44 eV below that of a pure Re reference ribbon. Analysis of the work function change as a function of surface concentration of Pt on the Topping model yielded values of 7.1×10-30 C m and 19.4 Å3 for the dipole moment and polarizability, respectively, of surface Pt atoms. Electron transfer from Pt to Re is opposite to that expected on the basis of published values of electronegativity and is interpreted as indicating significant exchange of 5d electrons in the alloy.