DISTRIBUTION OF INTERSTITIAL IMPURITIES ACROSS NB3SN ELECTROLYTIC COATINGS FOR MICROWAVE APPLICATIONS

Single-phase electrolytic Nb3Sn coatings for microwave applications ar e studied by Auger electron spectroscopy combined with depth profiling by Ar-ion milling. The effect of substrate surface condition on the d istribution of oxygen, carbon, and nitrogen interstitials across the s urface layer on the backside of the coating is examined. The surface c oncentration of nitrogen rises rapidly to become much higher than the bulk concentration as the surface layer is removed by ion milling. The possible mechanisms of this effect are discussed.