Bismuth calcium titanium sulfide [Bi6-xCaxTi5S16 (x = 3.08)]: the first example of a commensurate structure in the class of misfit-layer compounds

Abstract

A novel mixed-valence, quasi-two-dimensional bismuth calcium titanium(III/IV) sulfide, Bi^Ca^TisS^(x = 3.08) is reported as a commensurate structure for the first time in the class of misfit-layer compounds. Since the first synthesis of "PbTiS3",1 a large collection of structurally categorized misfit-layer compounds have been studied with general formulations close to AMQ3 and AM2Q5 (A = Sn, Pb, Bi, a rare-earth element; M = Ti, V, Cr, Nb, Ta).1-6 Their framework consist of an intergrowth of two types of layered lattices, i.e., mixed layers of NaCl/CdI2 for M = Ti, V, and Cr1-3 or NaCl/MQ2 (trigonal prismatic MQ6) for M = Nb and Ta.3-6 Owing to a mismatch between the two sublattices, the structural frameworks reported so far are incommensurate, subsequently structural analysis has been carried out by powder X-ray diffraction, electron diffraction, and, in some cases, single-crystal X-ray diffraction with structural solutions in two sublattices.5 Recently, these type of compounds have been extensively investigated for their interesting super-(1) (a) Sterzel, W.; Horn,

The synthesis and characterization of new [(BiSe)1.10]m[NbSe2]n, [(PbSe)1.10]m[NbSe2]n, [(CeSe)1.14]m[NbSe2]n and [(PbSe)1.12]m[TaSe2]n misfit layered compounds

“…The larger the positive value of x, the greater the atomic density of the planes in the rock salt layers relative to the dichalcogenide layers. Singlecrystal diffraction data from a commensurate misfit layered compound confirm this relationship [9]. Because of differing thermal expansion coefficients for the constituent layers, the value of x can be a function of temperature.…”

Synthesis, Structure, and Properties of a New Family of Mixed-Framework Chalcohalide Semiconductors: CdSbS2X (X = Cl, Br), CdBiS2X (X = Cl, Br), and CdBiSe2X (X = Br, I)

“…Syntheses. Crystals of CdBiS 2 Cl were initially obtained from the quaternary Bi/K/Ti/S reaction in an attempt to synthesize the Cd analogue of the misfit-layer compounds Bi 6 - x Ca x Ti 5 S 16 ( x = 3.08) using the eutectic flux CdCl 2 /KCl . Elemental bismuth (Aldrich, 99.99%), potassium (Mallinckrodt, 98%), titanium (Aldrich, 99.9%), and sulfur (Aldrich, 99.99%) were mixed in a 2:4:3:10 molar ratio.…”

Synthesis and characterization of quaternary La(Sr)S–TaS2 misfit-layered nanotubes

“…9 summarizes this analysis. The Raman spectra of MLC were analyzed first by Kisoda et al [51], and were further elaborated in [32] and [43]. The range between 100–150 cm −1 was assigned to the intralayer vibrations of the LnS lattice (Ln = rare earth).…”

“…The question then arises: how much of the rare-earth atom can be replaced by a divalent alkali earth atom, like strontium, while still retaining the stability of the MLC compound? This issue was deliberated in the case of the MLC Sr x La 1− x S–CrS 2 [40], Sr x La 1− x S–VS 2 [41–42], Ca x Bi 1− x S–TiS 2 [43] and Sr x La 1− x S–NbS 2 [44–45]. The stability limit with respect to the Sr exchange in the lattice varies from one MLC to the other.…”