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High‐Pressure Syntheses of Lanthanide Polysulfides and Polyselenides LnX 1.9 ( Ln = Gd–Tm, X = S, Se)
Author(s) -
Müller Carola J.,
Schwarz Ulrich,
Doert Thomas
Publication year - 2012
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201200304
Subject(s) - chalcogen , lanthanide , isostructural , crystallography , chemistry , tetragonal crystal system , crystal structure , chalcogenide , ternary operation , thulium , ion , materials science , doping , optoelectronics , organic chemistry , computer science , programming language
The polysulfides Ln S 1.9 and polyselenides Ln Se 1.9 of the lanthanide metals from gadolinium to thulium were prepared by high‐pressure high‐temperature synthesis. The compounds adopt the tetragonal CeSe 1.9 structure type in space group P 4 2 / n (No. 86) with lattice parameters of 8.531 Å ≤ a ≤ 8.654 Å and 15.563 Å ≤ c ≤ 15.763 Å for the sulfides and 8.869 Å ≤ a ≤ 9.076 Å and 16.367 Å ≤ c ≤ 16.611 Å for the selenides. The atomic pattern consists of puckered double slabs [ LnX ] + and planar chalcogenide layers with ten possible chalcogen positions, of which eight are occupied by chalcogen atoms forming dinuclear X 2 2– dianions, one by a single X 2– ion and one remaining vacant. This resembles a √5×√5 × 2 superstructure of the ZrSSi aristotype. Structural relationships to the aristotype and the related lanthanide polychalcogenides LnX 2– δ ( Ln = La–Tm, X = S–Te, δ = 0 – 0.3) are discussed. The samples synthesized under high‐pressure conditions ( p > 1 GPa) decompose slowly under release of sulfur or selenium at ambient conditions. The crystal structure of a partially degraded thulium‐polysulfide sample can be described as an incommensurate variant of the original TmS 1.9 motif. Additionally, the isostructural ternary compound Gd(S 1–x Se x ) 1.9 was synthesized and characterized by powder X‐ray diffraction.