Obtaining superconducting Nb3In layers

Nb-In samples of approximately 3-5 μm thickness were obtained by simultaneous evaporation of niobium and indium from two independent evaporators onto cold substrates of synthetic ruby and polycore. The initial In content varied from 18 up to 50%. Samples after spraying were annealed in quartz ampules at T=700-900 deg C during 8h. The best Nb3In samples were obtained in layers with initial indium content equal to 25-30% after annealing at T=800 deg C. The samples contained A15 phase and approximately 5% of BCC phase. The temperature of superconducting Tsub(s) transition determined in the middle of transition was equal to 8.2-9.6 K in different samples. The samples with Tsub(s)=9.2-9.6 K possessed the pronounced transition into superconducting state (ΔTsub(s)=0.1-0.2 K). The lattice constant a0=(5.290+-0.005) for A15 phase determined according to (611) doublets didn't change in the limits of experiment accuracy for the samples possessing the temperature of superconducting transition from 8.2 up to 9.6 K as well as in the case when 5-10% of free indium or BCC phase were present in the samples