Direct observation of dissociated dislocations in garnet

F. M. Allen, B. K. Smith, P R Buseck

Research output: Contribution to journalArticle

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Abstract

Dislocation core structures in garnet [grossularite (Ca 2.9Fe0.1 II)(Al1.9Fe 0.1 III)Si3.0O12] have been examined with near atomic resolution transmission electron microscopy. Dissociated dislocations have been observed as parallel a/4〈lll〉 partial dislocations that are separated by stacking faults. The partial dislocations have narrow cores (∼3 burgers vectors), and the stacking fault zone between the narrow partial dislocations is apparently a low-energy configuration that results from the occupancy of previously unfilled dodecahedral and tetrahedral sites. Previous studies of garnet dislocations suggested that dissociation involves departures from garnet stoichiometry (that is, trace amounts of impurities), but evidence of detectable amounts of impurities has not been found even in the highest resolution images. These results have implications for mantle mineral rheology and transformations as well as for ceramics of material science interest.

Original languageEnglish (US)
Pages (from-to)1695-1697
Number of pages3
JournalScience
Volume238
Issue number4834
StatePublished - 1987

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dislocation
garnet
stacking
image resolution
stoichiometry
rheology
ceramics
transmission electron microscopy
fault zone
mantle
mineral
energy

ASJC Scopus subject areas

  • General

Cite this

Allen, F. M., Smith, B. K., & Buseck, P. R. (1987). Direct observation of dissociated dislocations in garnet. Science, 238(4834), 1695-1697.

Direct observation of dissociated dislocations in garnet. / Allen, F. M.; Smith, B. K.; Buseck, P R.

In: Science, Vol. 238, No. 4834, 1987, p. 1695-1697.

Research output: Contribution to journalArticle

Allen, FM, Smith, BK & Buseck, PR 1987, 'Direct observation of dissociated dislocations in garnet', Science, vol. 238, no. 4834, pp. 1695-1697.
Allen, F. M. ; Smith, B. K. ; Buseck, P R. / Direct observation of dissociated dislocations in garnet. In: Science. 1987 ; Vol. 238, No. 4834. pp. 1695-1697.
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