Lushchik, A. ; Grants, R. ; Kudryavtseva, I. ; Manika, I. ; Popov, A.I. ; Seeman, V. ; Shablonin, E. ; Trautmann, C. ; Vasil'chenko, E. (2023)
Accumulation of structural defects and modification of micromechanical properties of MgAl2O4 single crystals irradiated with swift heavy ions.
In: Optical Materials, 142
doi: 10.1016/j.optmat.2023.114035
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

Single crystals of MgAl2O4 have been irradiated by 156-\MeV 132Xe and 2.25-GeV 197Au ions with fluences between 6.6 x 1010 and 2 x 1012 ions/cm2. After isodose ion-irradiation, the spectra of radiation-induced optical absorption (absorption of a pristine sample is subtracted) for the (100), (110) and (111) oriented crystals coincide. The fluence dependence of the concentration of several defects responsible for optical absorption at 4.5-7.1 eV have been analyzed. The integral of all five Gaussians, obtained via spectra decompositions and served as a measure of relevant defects, continuously increases with the fluence without any sign of saturation. Thus, similar to oxygen-vacancy-related F+ and F centers (Gaussians peaked at 4.8 and 5.3 eV, respectively), the defects responsible for elementary bands at 5.9, 6.6 and -7.1 eV are also of radiation-induced origin. The thermal stability of all defects has been determined via stepwise annealing of the irradiated samples. The tentative origin of the 5.9, 6.6 and -7.1 eV bands (their decay occurs by about 200 K higher than that for the Ftype centers) is considered. Nanoindentation measurements show an ion-induced increase of the sample hardness up to 30%. The hardening effect follows the evolution of the energy loss of the Xe and Au ions as a function of sample depth.

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