FORMATION OF DEFECTS IN THE ANION AND CATION SUBLATTICE OF MgAl<sub>2</sub>O<sub>4</sub> CRYSTALS IRRADIATED BY HIGH ENERGY XENON IONS

Abstract

In this work, the optical characteristics of an aluminum-magnesium spinel irradiated with 220 MeV Xe ions, which simulate the effect of nuclear fuel fission fragments were studied. During the experiments, the transmission spectra were measured in the IR region (240–12500) cm−1, the optical absorption spectra in the range (2–7) eV, the Raman spectra were measured by the ion penetration depth, from the surface to 30 µm. In the optical absorption spectrum (2–8) eV of irradiated spinel crystals, a wide complex band of radiation-induced absorption is observed with a peak in the region of 5.3 eV associated with electronic color centers of the F + and F type, and hole color centers are responsible for optical absorption at ~ (3–4) eV. In the near IR region, the crystal retains its transparency. In the Raman spectrum, in addition to the Raman modes characteristic of an ideal crystal, additional modes, A1g* (720 cm−1), and Eg* (385 cm−1), appear mainly in the form of an asymmetric shoulder of the main Eg mode. As the depth increases, the A1g*/Eg ratio increases, reaching a maximum value of 0.05 at 6 µm, and remains practically unchanged until the end of the Xe ion range of 14 µm, and with a further decrease to 0.045 at a depth of 30 µm. That is, when irradiated with 220 MeV Xe ions, cation mixing occurs along the ion path.