Electrochemical and thermal synthesis of Nb3Sn coatings on Nb substrates

Abstract

Electrochemical and thermal synthesis of superconducting Nb3Sn films were studied in this paper. The Nb3Sn films were obtained by 700 °C ex-situ vacuum annealing of electrochemically deposited bronze layer on Nb substrates. Precursors were prepared via electrochemical deposition performed from aqueous solutions at room temperature. Samples were then precisely electropolished to remove the a-few-micrometres of remnant bronze phase on top of the surface and then characterized. Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) allowed accurate measurement of the thickness of the Nb3Sn layer, whose average thickness was 1.2 μm. X-ray diffraction (XRD) patterns confirmed the existence of a cubic Nb3Sn phase (A15 structure). The highest Tc observed on these samples was 17.6 K. Owing to the superior film properties and the absence of high temperature treatment, this synthesis technique opens a new route towards copper-based Thin Film coated Superconducting Radio-Frequency (TFSRF) cavities.