A study of superconductivity in the (Hf0.5-xTaxZr0.5)V2HyC15 system

A study of superconductivity in the C15 system (Hf
0.5-x
Ta
x
Zr
0.5
)V
2
H
y
indicates that both the relationship between T
c
and y and the influence of hydrogen on the T
c
differ from those in the Pd-H system. The results of thermal neutron inelastic scattering show that acoustic phonons are important factors in the variation of T
c
. An evaluation of the distribution of hydrogen atoms in different interstices for small and large concentrations was made with the help of the theory developed by Jacob and Miedema. It seems that the superconducting transition temperature is enhanced when hydrogen atoms occupy mostly the 2Zr-2V interstices. A possible explanation of this effect is proposed.