The forces between polyatomic molecules I. Long-range forces

Abstract

The paramagnetic susceptibilities of b.c.c. transition metal alloys, Ti+V, V+Cr, Cr+Mn (up to 50% Mn), Zr+Nb, Nb+Mo, Hf+Ta, Ta+W, Ta+Re (up to 37.5 % Re), and Nb+Ta, have been measured in the temperature range 20 to 1350 $^\circ$C. The observed curve of the susceptibility, $\chi$, against composition (number of d+s electrons, q) has been found to be binodal and similar for the first, second and third series transition metal alloys. The susceptibility is a maximum for q $\sim$ 5 and a minimum at slightly less than 6. The temperature dependence of susceptibility for all the alloys measured is as expected from the band model on the assumption that the shape of the density of states curve follows the ($\chi$-q) curve. The paramagnetic susceptibility and its temperature dependence for the close-packed hexagonal phase is found to be quite different from that of the b.c.c. phase of the same composition; from the present measurements on h.c.p. alloys together with available data for pure metals a possible shape for the density of states curve of the close-packed structure is also proposed. These proposals are discussed in relation to the density of states curves derived theoretically by others.