Electronic excitations and defect creation in wide-gap MgO and Lu3Al5O12 crystals irradiated with swift heavy ions

A comparative study of radiation effects in two groups of single crystals with an energy gap of about 8 eV possessing drastically different lattice and electron energy structures − fcc MgO and Lu3Al5O12 with 160 atoms per a unit cell − has been performed using crystal irradiation with vacuum ultraviolet radiation, electrons, fast fission neutrons and, in particular, ∼2.2 GeV uranium ions. In MgO with the absence of self-trapping for valence holes, the localization of holes near impurity ions or bivacancies (both as-grown or induced by a plastic stress) has been detected. In LuAG, the peculiarities of the motion of hole polarons and excitons, the radius of which is smaller than the size of a unit cell, have been revealed and analysed. The irradiation of MgO and LuAG with swift heavy ions providing an extremely high density of electronic excitations causes also the nonimpact creation of long-lived Frenkel defects in an oxygen sublattice.