Tetrahedral rigid-body motion in silicates

K. L. Bartelmehs, R. T. Downs, G. V. Gibbs, M. B. Boisen, J. B. Birch

Research output: Contribution to journalArticle

12 Scopus citations


The atomic displacement parameters (ADPs) obtained from published refinements of silicate crystals measured at or below room temperature are examined to determine if TO4 (T = Al,Si) tetrahedra display rigid-body thermal motion. In many cases, the correlation found among the ADPs is consistent with the TLS model of rigid-body motion. The libration angle for rigid tetrahedra is quadratically dependent on the difference between the isotropic equivalent displacement parameter of the T and O atoms, Beq(T) and Beq(O), respectively. The value of Beq(O) is on average twice that of Beq(T), with an observed maximum value of ~2.0 Å3. -from Authors

Original languageEnglish (US)
Pages (from-to)680-690
Number of pages11
JournalAmerican Mineralogist
Issue number7-8
StatePublished - Jan 1 1995
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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    Bartelmehs, K. L., Downs, R. T., Gibbs, G. V., Boisen, M. B., & Birch, J. B. (1995). Tetrahedral rigid-body motion in silicates. American Mineralogist, 80(7-8), 680-690. https://doi.org/10.2138/am-1995-7-805