Preparation and characterization of nanocrystalline Nb ₃Al alloy

The nanocrystalline Nb ₃Al is prepared by the gas condensation method. The nanocrystalline Nb ₃Al size with injected 0.1 mbar helium pressure is about 15nm. During the gas condensation process, the superconductivity disappears at as-prepared NC Nb ₃Al with the mean particle size about 15 nm. After annealing the as-prepared NC Nb ₃Al at 500°C for 30 minutes, the mean particle size of NC Nb ₃Al is about 30 nm and the superconductivity appear with T _c about 16K. The results show that superconductivity can be achieved in nanocrystals with a rather smaller size than the typical penetration length of magnetic field. Further study of the influence of gas condensation alloying at high magnetic fields is crucial to the understanding of the superconductivity properties of NC Nb ₃Al.