First-principles calculation of positron lifetimes and affinities in perfect and imperfect transition-metal carbides and nitrides

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
1994
Major/Subject
Mcode
Degree programme
Language
en
Pages
10947-10957
Series
Physical Review B, Volume 49, Issue 16
Abstract
First-principles electronic structure and positron-state calculations for transition-metal carbides and nitrides are performed. Perfect NaCl structures as well as structures with metal or carbon/nitrogen vacancies are considered. The positron affinities and lifetimes are determined. The trends are discussed and the results are compared with recent positron lifetime measurements for group-IV and -V refractory metal carbides. The present analysis suggests, contradictory to an earlier interpretation, that positrons are trapped and annihilated at both carbon and metal vacancies. The concentration of metal vacancies detected by positron annihilation methods is probably very low, below the sensitivity limit of other experimental methods.
Description
Keywords
positron annihilation, electronic structure, transition metal carbide, transition metal nitride
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Citation
Puska, Martti J. & Sob, M. & Brauer, G. & Korhonen, T. 1994. First-principles calculation of positron lifetimes and affinities in perfect and imperfect transition-metal carbides and nitrides. Physical Review B. Volume 49, Issue 16. 10947-10957. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.49.10947.