  We investigated the structural, electronic, and superconducting properties of
Co1-xNixZr2, in which c-axis thermal expansion is systematically controlled. At
x (smaller than) 0.3, c-axis negative thermal expansion (NTE) was observed, and
the thermal expansion constant {\alpha}c approached zero with increasing x. At
x = 0.4-0.6, zero thermal expansion was observed, and positive thermal
expansion (PTE) appeared for x (greater than) 0.7. By analyzing the c/a ratio,
we observed a possible collapsed transition in the tetragonal lattice at around
x = 0.6-0.8. The lattice collapse results in c-axis PTE and the suppression of
bulk superconductivity.
