Ce2PdIn8, Ce3PdIn11 and Ce5Pd2In19—members of homological series based on AuCu3- and PtHg2-type structural units

Zusammenfassung Die Kristallstruktur der Verbindung Gd3Ga2 wurde mit Hilfe von Einkristallmethoden untersucht. Sie ist der erste Vertreter eines neuen Strukturtyps (Raumgruppe I4/mcm, a = 11,666 A , c = 15,061 A , v = 16). Isostrukturelle Verbindungen bilden sich mit Neodym, Samarium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Lutetium und Yttrium. Diskutiert wird die strukturelle Verwandtschaft von Gd3Ga2 mit anderen Verbindungen von seltenen Erdmetallen.

Kristallstruktur von Gd3Ga2 und isotypen Verbindungen

The crystal structure of the new indide CePt2In7 from powder data

Abstract A new ternary intermetallic compound with stoichiometry CePt 2 In 7 has been found. It crystallizes in the space group I 4/ mmm and represents a novel structure type (Pearson symbol tI 20, a  = 4.6093(2) A, c  = 21.627(1) A, Z  = 2). Crystal structure of CePt 2 In 7 was determined from X-ray powder pattern of a four-phase sample. Rietveld refinement resulted in R p  = 0.038, R wp  = 0.050, R exp  = 0.032, S  = 1.25. CePt 2 In 7 is a new member of the family of inhomogeneous linear structures built of the fragments of AuCu 3 and PtHg 2 parent structure types. Coordination polyhedra are a cuboctahedron for cerium, a deformed cube for platinum, and a cuboctahedron or a polyhedron derived from cuboctahedron for indium.

Crystal structure of the new indide CePt2In7 from powder data

New Germanides with an Ordered Variant of the Ce3Pt4Ge6 Type of Structure – The Compounds Ln3Pt4Ge6 (Ln: Pr–Dy)



Six new germanides Ln3Pt4Ge6 with Ln = Pr–Dy were synthesized by heating mixtures of the elements at 900 °C, annealing the inhomogeneous powders at 1050-1100 °C for six days and then cooling down from 700 °C in the course of two months. The crystal structures of Pr3Pt4Ge6 (a = 26.131(5), b = 4.399(1), c = 8.820(2) A), Sm3Pt4Ge6 (a = 25.974(3), b = 4.356(1), c = 8.748(1) A), and Dy3Pt4Ge6 (a = 26.079(5), b = 4.311(1), c = 8.729(2) A) were determined by single crystal X-ray methods. The compounds are isotypic (Pnma, Z = 4) and crystallize with an ordered variant of the Ce3Pt4Ge6 type of structure (Cmcm, Z = 2) consisting of CaBe2Ge2- and YIrGe2-analogous units. The platinum atoms are located in distorted square pyramids of germanium atoms and build up with them a three-dimensional network. The coordination polyhedra of the platinum and germanium atoms around the rare-earth metal atoms are pentagonal and hexagonal prisms. These are completed by some additional atoms resulting in coordination numbers of 14 and 15 respectively. The other germanides were investigated by powder methods resulting in the following lattice constants: a = 26.067(6), b = 4.388(1), c = 8.800(2) A for Ln = Nd; a = 25.955(7), b = 4.337(1), c = 8.728(2) A for Ln = Gd; a = 25.944(5), b = 4.322(1), c = 8.698(2) A for Ln = Tb. The atomic arrangement of Ln3Pt4Ge6 is compared with the well-known monoclinic structure of Y3Pt4Ge6.

Neue Germanide mit geordneter Ce3Pt4Ge6‐Struktur – Die Verbindungen Ln3Pt4Ge6 (Ln: Pr–Dy)

Crystal chemistry of series of inhomogeneous linear structures. I. Symmetry and numerical symbols of the structures composed of fragments of the structural types BaAl4, CaF2, AlB2, AuCu3, α-Fe and α-Po

Y. N. Grin

Papers

Crystal chemistry of series of inhomogeneous linear structures. I. Symmetry and numerical symbols of the structures composed of fragments of the structural types BaAl4, CaF2, AlB2, AuCu3, α-Fe and α-Po