THE HALL-EFFECT AND THE CONDUCTION ELECTRON-DENSITY IN NI-BASED AMORPHOUS-ALLOYS

New results for the normal Hall coefficient R0, the resistivity and the room-temperature coefficient of resistivity of five Ni-Bi-Si and six Ni-P amorphous (melt-quenched) alloys are reported. From these results, and results already reported, the authors have obtained rather detailed information on the variation in the conduction electron density with the metalloid concentration cm in the amorphous Ni-B-Si alloys. The results for the alloys with low cm extrapolate to those of liquid Ni, whereas the variation in the Fermi wavevector (deduced from R0) with c m supports the applicability of the Ziman-Faber theory for the explanation of the transport properties of these alloys. The contribution of the metalloid atoms to the conduction band is found to change at cm approximately=0.3, which is probably related to filling of the d band. This change occurs in the range of cm in which a significant change in the chemical short-range order has been observed. Although less detailed, the results for the Ni-P alloys follow the same trend as those for Ni-B-Si alloys and do not indicate any dramatic change in R0 at around cm approximately=0.24 as reported for electrodeposited Ni-P alloys.