Ca6LixAl23-x, Sr9Li7+xAl36-x, and Ba2Li3+xAl
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- 作者：Ulrich Hä ; ussermann ; Michael Wö ; rle ; and Reinhard Nesper
- 刊名：Journal of the American Chemical Society
- 出版年：1996
- 出版时间：November 27, 1996
- 年：1996
- 卷：118
- 期：47
- 页码：11789 - 11797
- 全文大小：309K
- 年卷期：v.118,no.47(November 27, 1996)
- ISSN：1520-5126
文摘
Investigations of the ternary systems M/Li/Al of the heavieralkaline earth metals M = Ca, Sr, Ba yieldedthree new intermetallic compounds which show interesting structuralrelationships.Ca6LixAl23-x(x 
11, Fm
m,a= 13.430(2) Å, Z = 4) crystallizes in theTh6Mn23 structure with all sites of themajority component occupied by Liand Al.Sr9Li7+xAl36-x(x 10.5, P63/mmc,a = 9.638(4) Å, c = 27.586(6) Å,Z = 2) is a relative of theSr3Mg13structure, andBa2Li3+xAl6-x(x 1.2, Rm, a= 9.946(1) Å, c = 26.992(3) Å, Z= 9) is a hexagonal relative of theTh6Mn23 type. The substructuresformed by Li and Al atoms are described in terms of two simple basisclusterswhich offer structural flexibility in their connectivity. Therelative stability of the substructures has beeninvestigatedwithin the simple tight-binding Hückel model. Calculatedenergy difference curves as a function of the valenceelectron concentration for these networks show a pronounced stabilitymaximum in the region of 2.5-2.7 electronsper network atom. This result fits the composition of theintermetallic compounds when applying the Zintl-Klemmconcept. In addition, Mulliken population analyses of extendedHückel calculations have been used to investigatethe site occupancies.
11, Fmm,a= 13.430(2) Å, Z = 4) crystallizes in theTh6Mn23 structure with all sites of themajority component occupied by Liand Al.Sr9Li7+xAl36-x(x 10.5, P63/mmc,a = 9.638(4) Å, c = 27.586(6) Å,Z = 2) is a relative of theSr3Mg13structure, andBa2Li3+xAl6-x(x 1.2, Rm, a= 9.946(1) Å, c = 26.992(3) Å, Z= 9) is a hexagonal relative of theTh6Mn23 type. The substructuresformed by Li and Al atoms are described in terms of two simple basisclusterswhich offer structural flexibility in their connectivity. Therelative stability of the substructures has beeninvestigatedwithin the simple tight-binding Hückel model. Calculatedenergy difference curves as a function of the valenceelectron concentration for these networks show a pronounced stabilitymaximum in the region of 2.5-2.7 electronsper network atom. This result fits the composition of theintermetallic compounds when applying the Zintl-Klemmconcept. In addition, Mulliken population analyses of extendedHückel calculations have been used to investigatethe site occupancies.