Thermopower and resistivity of amorphous and crystalline NiP

Data are presented for the thermopower and electrical resistivity of amorphous and crystalline Ni₇₆{P}₂₄$. Mean-free-path effects are large in the electrical resistivity but appear to be less significant in the thermopower. The diffraction model, modified to include the Pippard-Ziman constraint on the electronphonon interaction, is used to derive an expression for the thermopower in high-resistivity systems. The data on the amorphous phase are consistent with this modified diffraction model. The s-d model predictions, in contrast, are an order of magnitude too large and of the wrong sign.