Manuel C. Schaloske

Application of TEM for Real Structure Determination of Rare Earth Metal Compounds

Transmission electron microscopy (TEM) techniques are well adapted for the analysis of disordered crystals due to the minimization of space averaging effects. Hence, TEM enables the discovery of frequently overlooked, but new and chemically highly relevant aspects of solids, e. g. in the fields of rare earth metal (Ln) compounds.

The Starting Members of the Series Pr4n+2(C2)nBr5n+5 (n = 1, 2, 3)

The compounds Pr6(C2)Br10, Pr10(C2)2Br15 and Pr14(C2)3Br20 were prepared from PrBr3 and the appropriate amounts of Pr and C and characterized by X-ray structure analyses of single crystals. All three compounds crystallize in space group P1 with lattice parameters a = 7.571(2), b = 9.004(2), c = 9.062(2) Å ,α = 108.57(3), β = 97.77(3), γ = 106.28(3)◦ for Pr6(C2)Br10; a = 9.098(2), b = 10.127(2), c = 10.965(2) A° , α = 70.38(3), β = 66.31(3), γ = 70.84(3)◦ for Pr10(C2)2Br15; a = 9.054(2), b = 10.935(2), c = 13.352(3) Å , α = 86.27(3), β = 72.57(3), γ = 66.88(3)◦ for Pr14(C2)3Br20. They are members of a general series Ln4n+2(C2)nBr5n+5 and isostructural with the corresponding iodides known for Ln = La, Ce, Pr. Pr6(C2)Br10 was further characterized via transmission electron microscopy techniques Graphical Abstract The Starting Members of the Series Pr4n+2(C2)nBr5n+5 (n = 1, 2, 3)

Crystal structure of hexacerium decachloride dicarbide, Ce6Cl10C2

C2Ce6Cl10, monoclinic, C12/c1 (no. 15), a = 13.899(3) Å, b = 8.710(2) Å, c = 15.765(3) Å, = 98.22(3)°, V = 1888.9 Å, Z = 4, Rgt(F) = 0.035, wRref(F) = 0.085, T = 293 K. Source of material The compound was synthesized from Ce, CeCl3 and C with a molar ratio of 4 : 5 : 3. The educts were sealed in Ta capsules which in turn were enclosed in quartz glass ampoules under Ar and annealed at 1085 K for 48 days. The product Ce6Cl10C2 was nearly pure forming black polyhedral crystals, transparent orange in thin fragments. Discussion In the crystal structure of Ce6Cl10C2 the C atoms are tetrahedrally coordinated by Ce atoms. Two Ce4C tetrahedra are connected via a common edge to form units which arrange stepwise staggered along [001] (figure, top). The units are alternatingly tilted as shown in the bottom figure. All free edges of the tetrahedra are coordinated by Cl atoms. There are five independent Cl positions connecting the Ce atoms exclusively via inner-outerand outerinner-coordination to a 3-D network. The compound can be described in the ionic limit as (Ce)6(C)2(Cl)10. It is electron precise consistent with the transparency of the crystals. Ce6Cl10C2 is isostructural to the recently found compound Pr6Cl10C2 [1]. Z. Kristallogr. NCS 223 (2008) 189-190 / DOI 10.1524/ncrs.2008.0079 189