Electronic properties of amorphous and crystalline iron(x) copper(1-x) zirconium(2) alloys

The electronic contribution to the resistivity rho and its temperature dependence were investigated for amorphous and crystalline [Fe xCo1--x] 33.3Zr66.7 (0 ≤ x ≤ 1) alloys in the temperature range 80--300 K. As Fe-rich compositions may exhibit spin fluctuation effects, transport properties were not studied below 80 K where spin fluctuation effects must be taken into consideration. The compositional and structural integrity of the samples was verified by means of X-ray diffractometry, electron-microprobe analysis, and differential scanning calorimetry. It was also confirmed that the first crystallization product for all the compositions is the face-centered cubic phase with the NiTi2-type structure. A true comparison between amorphous and crystalline transport properties was thus possible. For the metallic glasses, it was observed that rho( T) had a temperature dependence of the form: A + Bexp(--T/Delta) in agreement with Mizutani who proposed this relation for glasses containing a significant number of d-electrons at EF. The characteristic temperature, Delta, was found to be related to the Debye temperature, theta D, and the parameter B to the electronic specific heat coefficient, gamma. The resistivity data for the crystalline tenary compounds exhibited a (c -- bT + aT2)-dependence. Both the glasses and their crystalline counterparts were characterized by negative temperature coefficients of the resistivity, alpha. However, for the glasses, alpha increased as the Fe content increased whereas for the crystalline compounds alpha decreased as the Fe content increased.