Void superlattice formation in electron irradiated CaF2: Theoretical analysis

Kuzovkov, V. N.; Kotomin, E. A.; Merzlyakov, P.; Zvejnieks, G.; Li, K.D.; Ding, Tianhua H; Wang, L.M.

doi:10.1016/j.nimb.2010.05.040

Cited by 4 publications

(1 citation statement)

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“…Irradiation of metals and other crystalline materials with energetic particles, such as electrons, neutrons, or ions, can result in displacement of target atoms from their regular lattice sites to generate Frenkel defects (vacancy and interstitial pairs). Considering the high technological importance of alkaline-fluorides, it is not surprising that, during the last years, they have been the subject of many experimental and theoretical studies. − …”

Section: Introductionmentioning

confidence: 99%

Ab Initio Calculations of the Transfer and Aggregation of F Centers in CaF₂

et al. 2012

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The F center and R center in CaF 2 crystals have been studied by using density functional theory (DFT) with a hybrid B3PW description of exchange and correlation. Our calculations show that the F-center diffusion barrier is equal to 1.67 eV. During the F-center transfer, the trapped electron is more delocalized than that in the regular F-center case, and the gap between defect level and CB in the α-spin state decreases. The surface F-center investigation shows the trend of F centers to locate near the surface. The association energy calculations of R centers indicate stable aggregations of isolated F centers. During the F-center aggregation, a considerable covalency forms between two neighboring fluorine vacancies with trapped electrons. Three incompletely paired electrons trapped in the R center have an up−down−up spin arrangement and induce three defect levels in the gaps between valence bands (VB) and conduction bands (CB) for both the αand β-spin polarized band structures, respectively. More defect bands lead to more complex electron transitions, which were classified into two F-and four M-like transitions. The DOS calculations clearly reveal the components of defect bands.

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