Kinetics of the electronic center annealing in Al2O3 crystals

Abstract

The experimental annealing kinetics of the primary electronic F , F + centers and dimer F2 centers observed in Al2O3 produced under neutron irradiation were carefully analyzed. The developed theory takes into account the interstitial ion diffusion and recombination with immobile F-type and F2-centers, as well as mutual sequential transformation with temperature of three types of experimentally observed dimer centers which differ by net charges (0, +1, +2) with respect to the host crystalline sites. The relative initial concentrations of three types of F2 electronic defects before annealing are obtained, along with energy barriers between their ground states as well as the relaxation energies.

Magnetron sputtering fabrication of α-Al2O3:Cr powders and their thermoluminescence properties

“…We guess the model of TL may be the following; under irradiation electron-hole pairs in the host were created and hole was trapped in Cr 3+ forming Cr 4+ centers. Electrons were trapped at anion vacancies complexes and known as the F2 -type centers (Kuzovkov et al, 2018). These vacancy complexes exist in highly Cr doped α-Al2O3.…”

Peculiarities of the diffusion-controlled radiation defect accumulation kinetics under high fluencies

“…) performed in terms of bimolecular reactions have shown unexpected result [19,23,24,25]: the migration energy E a of interstitial and the corresponding preexponential factor X are correlated and considerably depend on the fluence. The parameter X = N 0 RD 0 /β, where N 0 is initial defect concentration, Rrecombination radius for dissimilar defects [16,17], D 0 -diffusion pre-exponent for interstitials, and β heating rate.…”

“…Let's start our research with a brief overview of the abnormal behavior of radiation defect annealing kinetics. The work cycle [19,23,24,25] is based on the assumption that recombination of F centers with interstitials is a simple diffusion-controlled recombination of defects with equal initial concentrations. If we use dimensionless concentrations C(t) of defects (they are equal to unity at low temperatures), the law of decreasing concentrations over time is simple:…”

Thermal annealing and transformation of dimer F centers in neutron-irradiated Al2O3 single crystals

“…The optical absorption/emission bands related to the anion-vacancy-related elementary Frenkel defects − the F + and F centers (one or two elec-trons trapped by an oxygen vacancy) as well as their simplest aggregates, F 2 dimers (two adjacent oxygen vacancies) in different charge states have been revealed and thoroughly studied in the irradiated or additively colored (thermochemically reduced) Al 2 O 3 crystals [7][8][9][10][11][12] . Particular emphasis has been also paid to thermal annealing of F -and F 2 -types of radiation defects in α-Al 2 O 3 [ 6,9,11,12,17 ], as well as to the analysis of their annealing kinetics [ 17,18 ] and the simulation of the migration of oxygen interstitials, a mobile component in a thermally stimulated recombination of complementary Frenkel defects [19][20][21] .…”