Damage evolution in Au-implanted Ho(2)Ti(2)O(7) titanate pyrochlore
Résumé
Damage evolution at room temperature in Ho(2)Ti(2)O(7) single crystals is studied under 1 MeV Au(2+) ion irradiation by Rutherford backscattering spectroscopy along the (0 0 1) direction. For a better determination of ion-induced disorder profile, an iterative procedure and a Monte Carlo code (McChasy) were used to analyze ion channeling spectra. A disorder accumulation model, with contributions from the amorphous fraction and the crystalline disorder, is fit to the Ho damage accumulation data. The damage evolution behavior indicates that the relative disorder on the Ho sublattice follows a nonlinear dependence on dose and that defect-stimulated amorphization is the primary amorphization mechanism. Similar irradiation behavior previously was observed in Sm(2)Ti(2)O(7). A slower damage accumulation rate for Ho(2)Ti(2)O(7), as compared with damage evolution in Sm(2)Ti(2)O(7), is mainly attributed to a lower effective cross section for defect-stimulated amorphization. (c) 2010 Elsevier B.V. All rights reserved.