Point defects in alkaline-earth fluorides after thermal neutron irradiation

verfasst von: W. Buttler, H. J. Stöckmann, H. Ackermann, K. Dörr, F. Fujara, H. Grupp, P. Heitjans, G. Kiese, A. Körblein, D. Dubbers
Abstract: Single crystals of MgF₂, CaF₂, SrF₂ and BaF₂ have been irradiated with polarized, thermal neutrons at temperatures between 10 K and 300 K. The neutron capture process {Mathematical expression} creates polarized, β-active²⁰F(τ_β=16s) probe nuclei, which are displaced by the γ recoil and thus produce some nearby point defects. These defects have been studied by their influence on²⁰F NMR signals being monitored via the asymmetric β-decay radiation of the polarized²⁰F nuclei. From our results we conclude that in the fluorites CaF₂, SrF₂ and BaF₂ thermal neutron irradiation leads to the formation of anion Frenkel pairs, the predominant intrinsic defect in such crystals. Correlated recombination of these close Frenkel pairs with activation enthalpies of about 0.2 eV was observed at temperatures around 80 K. A second annealing stage occurs near 220 K corresponding to an activation enthalpy of about 0.6 eV. Possible annealing mechanisms responsible for this stage are discussed. In tetragonal MgF₂ two annealing stages were found at 13 K and 60 K corresponding to 0.037 eV and 0.17 eV, respectively. The stage at 60 K possibly reflects migration of the H entre whereas the interpretation of the 13 K stage remains an open question.
Externe Organisation(en): Philipps-Universität Marburg
Institut Laue-Langevin
Ruprecht-Karls-Universität Heidelberg
Typ: Artikel
Journal: Zeitschrift für Physik B Condensed Matter
Band: 45
Seiten: 273-282
Anzahl der Seiten: 10
ISSN: 0340-224X
Publikationsdatum: 12.1982
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Physik der kondensierten Materie
Elektronische Version(en): https://doi.org/10.1007/BF01321863 (Zugang: Unbekannt)

BibTeX

@article{f37054ba759d447381ac30b60a3fbd95,
title = "Point defects in alkaline-earth fluorides after thermal neutron irradiation",
abstract = "Single crystals of MgF2, CaF2, SrF2 and BaF2 have been irradiated with polarized, thermal neutrons at temperatures between 10 K and 300 K. The neutron capture process {Mathematical expression} creates polarized, β-active20F(τβ=16s) probe nuclei, which are displaced by the γ recoil and thus produce some nearby point defects. These defects have been studied by their influence on20F NMR signals being monitored via the asymmetric β-decay radiation of the polarized20F nuclei. From our results we conclude that in the fluorites CaF2, SrF2 and BaF2 thermal neutron irradiation leads to the formation of anion Frenkel pairs, the predominant intrinsic defect in such crystals. Correlated recombination of these close Frenkel pairs with activation enthalpies of about 0.2 eV was observed at temperatures around 80 K. A second annealing stage occurs near 220 K corresponding to an activation enthalpy of about 0.6 eV. Possible annealing mechanisms responsible for this stage are discussed. In tetragonal MgF2 two annealing stages were found at 13 K and 60 K corresponding to 0.037 eV and 0.17 eV, respectively. The stage at 60 K possibly reflects migration of the H entre whereas the interpretation of the 13 K stage remains an open question.",
author = "W. Buttler and St{\"o}ckmann, {H. J.} and H. Ackermann and K. D{\"o}rr and F. Fujara and H. Grupp and P. Heitjans and G. Kiese and A. K{\"o}rblein and D. Dubbers",
year = "1982",
month = dec,
doi = "10.1007/BF01321863",
language = "English",
volume = "45",
pages = "273--282",
journal = "Zeitschrift f{\"u}r Physik B Condensed Matter",
issn = "0340-224X",
publisher = "Springer New York",
number = "4",
}