Annealing effect and floating zone refining of copper under hydrogen atmosphere

High purity Cu is prepared by a Boating zone refining method. The effect of the annealing atmosphere on the residual resistivity ratio of Cu is examin ed for purity evaluation of floating zone refined Cu. An advantage of hydro gen annealing as a heat treatment for residual resistivity measurement of C u compared to ultra high vacuum annealing has been revealed. The residual r esistivity ratio of the starling material, 99.9999% Cu, was 3200, and that of purified Cu was 36000. This RRR is the highest value reported on anneale d samples under a strong reducting atmosphere. Floating zone refining under reduced hydrogen atmosphere is effective for the preparation of ultra high purity Cu.