Calcium platinum aluminium, CaPtAl

Abstract

Key indicators: single-crystal X-ray study; T = 293 K; mean (Pt-Al) = 0.003 Å; R factor = 0.028; wR factor = 0.064; data-to-parameter ratio = 25.5.A preliminary X-ray study of CaPtAl has been reported previously by Hulliger [J. Alloys Compd (1993), 196, 225-228] based on X-ray powder diffraction data without structure refinement. With the present single-crystal X-ray study, we confirm the assignment of the TiNiSi type for CaPtAl, in a fully ordered inverse structure. All three atoms of the asymmetric unit have .m. site symmetry. The structure features a 1 3[AlPt] open framework with a fourfold coordination of Pt by Al atoms and vice versa. The Ca atoms are located in the large channels of the structure. Related literatureFor a previous X-ray powder diffraction study of CaPtAl, see: Hulliger (1993). For related compounds, see: DascoulidouGritner & Schuster (1994); Merlo et al. (1996). For structural systematics and properties of the TiNiSi structure type, see: Kussmann et al.

On Ternary Intermetallic Aurides: CaAu2Al2, SrAu2–xAl2+x and Ba3Au5+xAl6–x

“…Besides the ternary equiatomic intermetallic compounds AET Al with AE being an alkaline earth metal and T being an electron rich transition metal ( T = Pd, Pt, Ag, Au) about two dozen other ternary compounds have been reported. For the equiatomic ones CaPdAl (own structure type), CaAgAl (MgZn 2 type), CaPtAl, CaAuAl,, (both TiNiSi type) along with the recently reported BaAuAl have been synthesized and structurally characterized. Attempts to synthesize “SrPdAl”, “SrPtAl”, and “BaPtAl”, yielded Sr 2 Pd 4 Al 5 , Sr 2 Pd 2 Al, SrPt 3 Al 2 , and Ba 3 Pt 4 Al 4 .…”