Vacancy-antistructure defect interaction diffusion in β-LiAl and β-LiIn

J. C. Tarczon*, W. P. Halperin, S. C. Chen, J. O. Brittain

*Corresponding author for this work

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

The lithium mass transport mechanisms of the NaTl-type intermetallic compounds β-LiAl and β-LiIn were studied by using the pulsed-field-gradient (PFG) nuclear magnetic resonance (NMR) spin-echo technique over a temperature range of 297-485 K. The lithium self-diffusion coefficients in β-LiAl alloys were found to follow Arrhenius behavior. The lithium diffusion coefficient and the associated diffusion constant D0 (Li) and activation energy 〈E〉 decrease with increasing lithium content. The results can be interpreted if two types of vacancy point defects are considered: vacancies associated with immobile antistructure defects and vacancies which are otherwise free. A vacancy-diffusion mechanism based on two mean effective jump times, τA and τBτBA = 9.0), for these two types of vacancies yields a quantitative description of the dependence of the lithium diffusion rate on defect concentrations under a VLi-LiAl attractive interaction at a nearest neighbor distance. Very high values of lithium diffusivities (approximately 10-6 cm2 s-1 at room temperature) which increase with decreasing lithium content were observed in β-LiIn alloys. The lithium self-diffusion coefficient obeys the Arrhenius relation over the temperature range 300-400 K. The diffusion constant D0 (Li) and activation energy 〈E〉 determined from the Arrhenius relation decrease with increasing lithium content. The results suggest that there is a repulsive interaction between the vacancy VLi and the antistructure atom LiIn. Theoretical analyses based on a three-effective-jump-times diffusion model indicate that this VLi-LiIn repulsive interaction is so strong that it extends well into the second nearest-neighbor distance.

Original languageEnglish (US)
Pages (from-to)99-108
Number of pages10
JournalMaterials Science and Engineering A
Volume101
Issue numberC
DOIs
StatePublished - May 1988

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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