The behavior of a niobium target during magnetron sputtering in reactive oxygen and/or nitrogen atmosphere using a pulsed power supply has been investigated. No arcing was observed at any deposition conditions. Deposition rates in the system Nb–O–N were in the range of 0.8–3.6 Am/h. The highest rates were found for low oxygen flows in the Nb–O system. The chemical composition, morphology and crystallographic structure of deposited Nb–O and Nb–O–N coatings have been studied by energy dispersive X-ray spectroscopy, scanning electron microscopy and X-ray diffraction, respectively. Hardness measurements were performed using the instrumented indentation test. As for other Me–O–N systems (Me=metal) the oxygen has a strong influence on the chemical composition of the Nb oxynitride coatings due to its higher reactivity compared with nitrogen. Nb–O coatings deposited at oxygen gas flows >5 sccm look transparent, at lower oxygen gas flows the coatings appear metallic. Oxygen gas flows >5 sccm do not influence the chemical composition or hardness of the coatings appreciably (saturation effect). Additions of nitrogen shift the transition ‘‘metallic–transparent’’ to lower oxygen gas flows. Nb–O and Nb– O–N coatings seem to be X-ray amorphous. The hardness of the transparent Nb–O–N coatings is lower than the hardness of a metallic niobium coating.
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