Chemical Twinning in Zintl Phases†
datasetposted on 15.09.1999 by Fabio Zürcher, Steffen Wengert, Reinhard Nesper
Datasets usually provide raw data for analysis. This raw data often comes in spreadsheet form, but can be any collection of data, on which analysis can be performed.
In the systems Ba/Mg/(Si, Ge), two new ternary Zintl phases with the compositions BaMg4Si3 and BaMg4Ge3 were found and structurally characterized. Both compounds are isotypic and crystallize with a new structure type [BaMg4Si3, P4/mmm, Z = 1, a = 4.6115(9) Å, c = 8.615(2) Å; BaMg4Ge3, P4/mmm, Z = 1, a = 4.6335(8) Å, c = 8.746(2) Å]. The anionic partial structure is built of X26- dumbbells and isolated X4- ions (X = Si, Ge), and the structure can be described according to the Zintl−Klemm-Busmann concept with the formulation (Ba2+)(Mg2+)4[X26-][X4-]. The BaMg4X3 structure can also be described as a result of the fusion of the structures of Mg2X and BaMg2X2. In this regard, BaMg4Si3 and BaMg4Ge3 are very striking examples of chemical twinning.