Phonon spectra of A-15 compounds and ternary molybdenum chalcogenides

A survey is given on studies of the phonon spectra of several A-15 compounds by inelastic neutron scattering on polycrystalline samples. Comparison of the results for V3Si, V3Ge, N3Ga, Nb3Sn and Nb3Al at 297 K lead to the conclusion that the interatomic forces are to a good approximation the same for all compounds with 4.75 valence electrons but are reduced by about 20% for those with 4.5 valence electrons. For all compounds investigated a softening of the phonon frequencies on cooling is observed which is most pronounced for those materials with the highest T/sub c/ values. From a comparison of the results with the experimentally determined Eliashberg function of Nb3Sn information is derived about the energy dependence of the electron-phonon coupling function α2