Phase range of the type-I clathrate Sr 8Al xSi 46-x and crystal structure of Sr 8Al 10Si 36

John H. Roudebush, Naohito Tsujii, Antonio Hurtando, Håkon Hope, Yuri Grin, Susan M. Kauzlarich

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Samples of the type-I clathrate Sr 8Al xSi 46-x have been prepared by direct reaction of the elements. The type-I clathrate structure (cubic space group Pm3̄n) which has an Al-Si framework with Sr 2+ guest atoms forms with a narrow composition range of 9.54(6) ≤ x ≤ 10.30(8). Single crystals with composition A 8Al 10Si 36 (A = Sr, Ba) have been synthesized. Differential scanning calorimetry (DSC) measurements provide evidence for a peritectic reaction and melting point at ∼1268 and ∼1421 K for Sr 8Al 10Si 36 and Ba 8Al 10Si 36, respectively. Comparison of the structures reveals a strong correlation between the 24k-24k framework sites distances and the size of the guest cation. Electronic structure calculation and bonding analysis were carried out for the ordered models with the compositions A 8Al 6Si 40 (6c site occupied completely by Al) and A 8Al 16Si 30 (16i site occupied completely with Al). Analysis of the distribution of the electron localizability indicator (ELI) confirms that the Si-Si bonds are covalent, the Al-Si bonds are polar covalent, and the guest and the framework bonds are ionic in nature. The Sr 8Al 6Si 40 phase has a very small band gap that is closed upon additional Al, as observed in Sr 8Al 16Si 30. An explanation for the absence of a semiconducting "Sr 8Al 16Si 30" phase is suggested in light of these findings.

Original languageEnglish (US)
Pages (from-to)4161-4169
Number of pages9
JournalInorganic Chemistry
Volume51
Issue number7
DOIs
StatePublished - Apr 2 2012

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clathrates
Crystal structure
crystal structure
Chemical analysis
Covalent bonds
covalent bonds
Electronic structure
melting points
Melting point
Cations
Differential scanning calorimetry
Energy gap
heat measurement
Single crystals
electronic structure
cations
Atoms
scanning
Electrons
single crystals

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

Roudebush, J. H., Tsujii, N., Hurtando, A., Hope, H., Grin, Y., & Kauzlarich, S. M. (2012). Phase range of the type-I clathrate Sr 8Al xSi 46-x and crystal structure of Sr 8Al 10Si 36 Inorganic Chemistry, 51(7), 4161-4169. https://doi.org/10.1021/ic2024814

Phase range of the type-I clathrate Sr 8Al xSi 46-x and crystal structure of Sr 8Al 10Si 36 . / Roudebush, John H.; Tsujii, Naohito; Hurtando, Antonio; Hope, Håkon; Grin, Yuri; Kauzlarich, Susan M.

In: Inorganic Chemistry, Vol. 51, No. 7, 02.04.2012, p. 4161-4169.

Research output: Contribution to journalArticle

Roudebush, JH, Tsujii, N, Hurtando, A, Hope, H, Grin, Y & Kauzlarich, SM 2012, 'Phase range of the type-I clathrate Sr 8Al xSi 46-x and crystal structure of Sr 8Al 10Si 36 ', Inorganic Chemistry, vol. 51, no. 7, pp. 4161-4169. https://doi.org/10.1021/ic2024814
Roudebush JH, Tsujii N, Hurtando A, Hope H, Grin Y, Kauzlarich SM. Phase range of the type-I clathrate Sr 8Al xSi 46-x and crystal structure of Sr 8Al 10Si 36 Inorganic Chemistry. 2012 Apr 2;51(7):4161-4169. https://doi.org/10.1021/ic2024814
Roudebush, John H. ; Tsujii, Naohito ; Hurtando, Antonio ; Hope, Håkon ; Grin, Yuri ; Kauzlarich, Susan M. / Phase range of the type-I clathrate Sr 8Al xSi 46-x and crystal structure of Sr 8Al 10Si 36 In: Inorganic Chemistry. 2012 ; Vol. 51, No. 7. pp. 4161-4169.
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