Isothermal oxidation behavior of pure nickel and its lanthanum ion-implanted sample were studied at 900 ℃ in air. The surface morphology and microstructure of NiO films formed on both samples were examined by scanning electronic microscopy(SEM) and transmission electronic microscopy(TEM). Laser Raman spectrometer and X-ray diffraction spectrometer(XRD) were used to study the stress status in NiO films formed on La-free and La-implanted nickel. Secondary ion massive spectrum(SIMS) was used to examine Ni, O and La element depth distribution in oxide films. Results showed that La implantation remarkably reduced the growing speed and grain size of NiO film. Meanwhile it changed the oxide film growing mechanism from predominant Ni2+ cation outward diffusion to O2- anion inward diffusion. XRD and Raman testing results showed the stress declination effect due to La-implantation, while the discrepancy between the two testing results was fully analyzed regarding to the heterogeneous stress distribution in oxide film and the rare earth effect during the film growing process.
