Superconductivity in (Zr1-xTax)Nz (0.1 ≤ x ≤ 0.9)

Dc magnetic susceptibility measurements between 1.8 and 15 K have been carried out on nine samples in (Zr1-xTax)Nz (x = 0.1-0.9) to study the superconducting phase transitions in this N-containing system. It is found that the superconducting transition temperature Tc increases with Ta concentration up to x = 0.6, then decreases. A Tc,onset peak value of 13.4 K occurs in the sample with nominal composition (Zr0.4Ta0.6)N0.39. The improvement, with respect to pure ZrN (Tc 10.7 K), on the superconducting critical temperature Tc is about 25% by optimal doping with Ta.