2013 Volume 54 Issue 7 Pages 1140-1144
Chromium oxynitride Cr(N,O) thin films were prepared by pulsed laser deposition in a highly reactive atmosphere, which consisted of pure oxygen gas and nitrogen plasma from a radio-frequency radical source. In order to control the oxygen content in the thin films, oxygen partial pressure (PO2) in the chamber was varied from 5 to 10 × 10−5 Pa under a fixed total pressure of 1.5 × 10−2 Pa. The thin films were then characterized by X-ray diffraction, infrared spectroscopy, electron energy loss spectroscopy and nano-indentation testing. It was found that the oxygen content of the thin films changed from 0 to 62 mol% with increasing PO2. The thin films with only the NaCl-type (B1) Cr(N,O) phase were prepared under PO2 < 7.5 × 10−5 Pa. The chromium content of the B1 phase decreased from 47 mol%, which was close to the stoichiometric composition of CrN, to 40 mol% when the oxygen content was increased. The hardness increased up to 32 GPa with increasing PO2 up to 7.5 × 10−5 Pa.