ELECTRICAL-RESISTIVITY AND THERMOELECTRIC-POWER OF AMORPHOUS NIOBIUM-NICKEL ALLOYS SYNTHETIZED BY VAPOR QUENCHING

Thin film samples (10-20 μ thick) of niobium-nickel alloys in the composition range Nb-5 to 95 at % Ni were vapour quenched by R. F. sputtering onto fused quartz substrates held at a temperature of 450 K. It was found that fully glassy alloys were synthetized in the composition range Nb-30 to 85 at % Ni, 2·5 times larger than reported for splat-quenched alloys. Crystallization temperatures exhibited maxima near the eutectic composition and are comparable to those of splat-quenched materials. At room temperature, the electrical resistivity ρ{variant} of these alloys lies between 176-210 μΩ cm, and the absolute thermoelectric power S between 2·20-2·52 μV/K. On increasing the temperature from 4·2 to 775 K, up to which the amorphous alloys are stable, the resistivity of the alloy with χ=0·50 decreases by about 1·5%; the value of d ρ{variant}/dT progressively increases with increasing Ni content, becoming positive at 0·50<x<0·75. In the range 90 to 400 K, the dS/dT of all alloys lies between 6-8·5×10-3μV deg-2. The electrical behaviour of these alloys may be treated in terms of electron scattering in disordered structures assuming the nearly free-electron model, in a manner analogous to Ziman's theory of electronic transport in liquid metals. © 1979 Academia, Publishing House of the Czechoslovak Academy of Sciences.