Bismuth Phase Dependent Growth of Superconducting NiBi3 Nanorods

We report a study on the growth of NiBi3 nanowires and nanorods during the preparation of super-conducting NiBi3 films by co-evaporation of Ni and Bi. We find that NiBi3 films grown via co-evaporation of Ni and Bi metals achieve higher transition temperatures (4.4 K) compared even to the single crystal NiBi3. However, in certain parameter space, the film surfaces were spattered with nanoscale features, such as nanowires and nanorods. Ambient temperature deposition resulted in poly-crystalline NiBi3 nanorods which were controllable with the evaporation rate of Bi. Deposition at elevated temperatures promoted the emergence of long single crystalline NiBi3 nanorods. High resolution transmission electron microscopy measurements confirmed the crystalline behaviour of the nanorods. We believe that NiBi3 nanowires form in a process analogous to the well known vapor-liquid-solid process, as we observe an amorphous Bi cap on the nanorods. From glancing angle X-ray diffraction measurements we identify that the presence of trigonal Bi with hexagonal primitive cell in the film promotes the nucleation of nanorods. Electrical transport on a single NiBi3 nanowire shows a superconducting transition of 4.3 K.& COPY; 2023 Elsevier B.V. All rights reserved.

Automated summary

We conducted a study on the growth of NiBi3 nanowires and nanorods during the preparation of super-conducting NiBi3 films by co-evaporation of Ni and Bi. The films grown via this method achieve higher transition temperatures compared to single crystal NiBi3, but sometimes nanoscale features like nanowires and nanorods appear on the film surfaces. The growth of NiBi3 nanorods could be controlled by the deposition rate of Bi and elevated temperatures promote the emergence of long single crystalline nanorods.