Electron diffraction observations from some so-called 'LnMS₃' layer compounds isostructural with '~LaCrS₃' and from cannizzarite, ~Pb₄₆Bi₅₄S₁₂₇

Abstract

Electron diffraction data are reported and discussed for a series of so-called 'Ln,/~S 3' compounds (Ln = La, Ce, Pr and Nd, M = Cr; Ln --La, M = Ti, V and Cr) and for cannizzarite (~46PbS.27Bi2Sa). The structures of all these compounds consist of two layer types alternating along the stacking direction -which is the zone axis in most instances. In the first group the mismatch between the layers varies slightly (by up to 2.5%) as the cations are varied. In the last we find only the ~ 12/7 and 17/10 layer matches, and not their combinations 46/27 and 41/24 as reported by Matzat [Acta Cryst. (1979), B35, 133-1361

The incommensurate misfit layer structure of (PbS)1.14NbS2, `PbNbS3' and (LaS)1.14NbS2, `LaNbS3': an X-ray diffraction study

“…The effect of neglecting the modulation is already visible in the exceptionally high values of the temperature factor UI1 (along the a axis) of PbS and LaS. The compound (LaS)vz0CrS2 was the first compound found with a misfit layer structure containing a transition-(PbS) I.14NbS2, 'PbNbS3' AND (LaS) I.14NbS2, 'LaNbS3' metal dichalcogenide (Kato, Kawada & Takahashi, 1973;Otero-Diaz, FitzGerald, Williams & Hyde, 1985;Williams & Hyde, 1988 (Murugesan, Ramesh, Gopalakrishnan & Rao, 1981) probably have the same or a strongly related structure.…”

Synthesis and Electron Microscopy Study of the Quaternary Misfit Layer Chalcogenides {(Bi,Nd)S}1+δCrS2 and {(Pb,Nd)Se}1+δ(NbSe2)2

“…Since the discovery, in 1977, of the first misfit compound “LaCrS 3 ”, many systems have been studied. − Most of the misfit layered compounds reported are based in a QH, QHH, or, rarely, a QHHH stacking sequence . More recently, by using the modulated elemental reactants technique (MER) metastable compounds, named ferecrystalline compounds, with compositions ([SnSe] 1+δ ) m (MoSe 2 ) n and ([SnSe] 1+δ ) m (NbSe 2 ) n with m , n up to 20 ( m and n denote the thickness of each layer) have been synthesized. , …”

Strukturverfeinerung des Kompositkristalls im mehrdimensionalen Raum

“…Im Rahmen der vorliegenden Arbeit ist diese Zusammensetzung angenommen. Ferner sei noch zu erwfihnen, dab k/irzlich zahlreiche komplexe Sulfide mit fihnlichen Strukturen synthetisch hergestellt worden sind (Guemas, Rabu, Meerschaut & Rouxel, 1988;Williams & Hyde, 1988;Meerschaut, Rabu & Rouxel, 1989;Oosawa, Gotoh & Onoda, 1989).…”