Electronic structure of ZnCNi3 -: art. no. 060507

According to a recent report by Park , ZnCNi3 is isostructural and isovalent to the superconducting (T(c)similar to8 K) antiperovskite, MgCNi3, but shows no indication of a superconducting transition down to 2 K. A comparison of calculated electronic structures shows that the main features of MgCNi3, particularly the van Hove singularity near the Fermi energy (E-F), are preserved in ZnCNi3. Thus, the reported lack of superconductivity in ZnCNi3 is not explainable in terms of T-c being driven to a very low value by a small Fermi level density of states. We propose that the lack of superconductivity, the small value of the linear specific heat coefficient gamma and the discrepancy between theoretical and experimental lattice constants can all be explained if the material is assumed to be a C-deficient alpha-ZrCNi3 similar to the analogous nonsuperconducting phase of MgCNi3.