  Compositionally complex alloys (CCAs) are a new category of high-entropy
materials containing more than two high-entropy phases in an alloy sample. We
applied the concept of CCA to a A15-type compound superconductor V3X where X
site is occupied by Al, Si, Ga, Ge, and Sn. The V3X sample shows bulk
superconductivity with a transition temperature (Tc) of 6.4 K, which is close
to the Tc of V3Ge. The upper critical field (Bc2(0)) of V3X estimated from
magnetic susceptibility is 8.8 T, which is ~50% higher than that of V3Ge
(Bc2(0) = 5.8 T). The presence of at least five different A15 phases with high
configurational entropy of mixing were revealed. We consider that the examined
V3X sample is an example system of CCA-type superconducting intermetallic
compound.
