SIMS artifacts in the near surface depths profiling of oxygen conducting ceramics

Using ultra low energy SIMS ion beams of oxygen and nitrogen, the very near surface region of an¹⁶O annealed La_0.8Sr_0.2MnO₃pellet has been depth profiled in order to investigate the surface layer composition and to determine any perturbing ion beamtarget interactions. By ratioing the measured cation species, the results indicate that only Sr segregation at the near surface can be clearly identified, and no separate oxide layer was present on the top surface. By monitoring the build up of the altered layer associated with SIMS depth profiling, it was observed that the depth at which the altered layer was fully formed was deeper than the expected projected range,R_p, of the ion beam. These results confirm Sr excess in the near surface, which will have an effect on the vacancy concentrationand therefore the surface exchange coefficient,k.