  Studies on high-entropy alloy (HEA) superconductors have recently been
increasing, particularly in the fields of materials science and condensed
matter physics. To contribute to research on new HEA-type superconductors, in
our study we synthesized polycrystalline samples of A15-type superconductors of
Nb3Al0.2Sn0.2Ge0.2Ga0.2Si0.2 (#1) and Nb3Al0.3Sn0.3Ge0.2Ga0.1Si0.1 (#2) with an
HEA-type site by arc melting. Elemental and structural analyses revealed that
the compositions of the obtained samples satisfied the HEA state criteria.
Superconducting transitions were observed at 9.0 and 11.0 K for #1 and #2,
respectively, in the temperature dependence of magnetization and electrical
resistivity. Specific heat measurements revealed that the Sommerfeld
coefficient, Debye temperature, and {\Delta}C/{\gamma}Tc for the obtained
samples were close to those reported for conventional Nb3Sn family
superconductors.
