Metastable self-trapping of positrons in MgO
Authors:
- 1 January 1997
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 55 (1) , 243-249
Abstract
Low-temperature positron annihilation measurements have been performed on MgO single crystals containing either cation or anion vacancies. The temperature dependence of the S parameter is explained in terms of metastable self-trapped positrons which thermally hop through the crystal lattice. The experimental results are analyzed using a three-state trapping model assuming transitions from both delocalized and self-trapped states to deep trapped states at vacancies. The energy level of the self-trapped state was determined to be (62±5) meV above the delocalized state. The activation enthalpy for the hopping process of self-trapped positrons appears to depend on the kind of defect present in the crystals.Keywords
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