Depth distribution of oxygen vacancies in 1 MeV Li + -irradiated KTiOPO 4

Electron-energy-loss spectra have been recorded from cross-sectional transmission electron microscopy samples of Li + -irradiated KTiOPO 4 single crystals. By evaluating the intensity in the pre-edge shoulder of the OK ionization edge, the depth distribution of O vacancies in radiation-damaged KTiOPO 4 was monitored. Li + irradiation at 295K and Li + irradiation at 100K generate very similar defect profiles except for an additional superficial maximum in the room-temperature-irradiated sample. Vacancy distributions in the O sublattice can be monitored on the nanometre scale by the method introduced. The methodology is potentially applicable to a wide range of materials, when pertinent defect-sensitive features in electron-energy-loss spectra are evaluated, and its sensitivity is expected to become further improved with the availability of monochromated electron sources in transmission electron microscopes.