Superconductivity in the new Nb5Si3−xBx phase

In the Nb–Si system the αNb5Si3 phase is not a superconductor. Considering the high solubility of this phase for boron, in this work it has been evaluated the effect of boron doping in αNb5Si3 on the electrical and magnetic properties of the produced materials. It has been shown that boron doping promoted superconductivity for all studied compositions. The Nb5Si2.4B0.6 sample presented the maximum superconducting critical temperature (7.8 K) with upper critical magnetic field close to μoH∼4.2 T. Thus, this work shows for the first time superconductivity in a phase with Cr5B3-prototype structure.