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The article discusses a study based on preparation of structurally related metastable compounds, and (PbTe)1.17] m(TiTe2) n. Topics discussed for the study include application of diffusion-limited and high-temperature reactions in preparing new solid-state compounds, use of high-resolution X-ray diffraction scans for annealing study, and use of vacuum deposition techniques to produce a layered precursor of alternating elemental constituents.

The title compound is prepared by annealing (350 °C, N2) a system of 28 repetitions of sputtered layer sequences of Ti-Se-Ti-Se-Pb-Se. [ABSTRACT FROM AUTHOR]

A family of structural isomers [(SnSe)1.05]m(MoSe2)n were prepared using the modulated elemental reactant method by varying the layer sequence and layer thicknesses in the precursor. By varying the sequence of Sn-Se and Mo-Se layer pairs "E deposited and annealing the precursors to self-assemble the targeted compound, all six 3 possible isomers [(SnSe)1.05]4(MoSe2)4, [(SnSe)1.05]3 (MoSe2)3[(SnSe)1.05]1(MoSe2)1, [ ( SnSe )1.05 ] 3 ( MoSe2 ) 2 [ ( SnSe ) 1.05 ] 1 ( MoSe2 ) 2, [ ( SnSe ) 1.05 ] 2 ( MoSe2 ) 3 [ ( SnSe ) 1.05 ] 2 ( MoSe2 ) 1, J [ (SnSe )1.05] 2 (MoSe2 )1 [ ( SnSe ) 1.05] 2(MoSe2) 2[(SnSe )1.05] 1(MoSe2) 1, and | [(SnSe)1.05]2(MoSe2)2[(SnSe)1.05]1(MoSe2)1[(SnSe)1.05]1(MoSe2)1 were prepared. The | structures were characterized by X-ray diffraction and electron microscopy which showed that all of the compounds have very similar c-axis lattice parameters and in-plane constituent lattice parameters yet distinct isomeric structures. These studies confirm that the structure, order, and thickness of the constituent layers match that of the precursors. The cross-plane thermal conductivity is found to be very low (-0.08 Wm-1 K-1) and independent of the number of SnSe-MoSe2 interfaces within uncertainty. The poor thermal transport in these layered isomers is attributed to a large cross-plane thermal resistance created by SnSe-MoSe2 and MoSe2-MoSe2 turbostratically disordered van der Waals interfaces, the density of which has less variation among the different compounds than the SnSe-MoSe2 interface density alone. [ABSTRACT FROM AUTHOR]

The structures of three new misfit layer compounds, [(PbSe)0.99]1[WSe2]1, [(PbSe)1.00]1[MoSe2]1, and [(SnSe)1.03]1[MoSe2]1, prepared as thin films from designed elementally modulated reactant precursors, have been investigated by synchrotron X-ray diffraction and scanning transmission electron microscopy. This is the second report of a misfit layer compound based on tin selenide and the first structure determinations of tungsten- and molybdenum-containing misfit layer compounds. The compounds have mismatches in both the a- and b-axis (in-plane) lattice parameters of the component structural units, which result in misfit parameters, δ, both greater and smaller than zero. Pole figures of hk0-type reflections indicate that c-axis-oriented (basal plane) dichalcogenide-structured units are randomly oriented within the a- b plane. The widths of diffraction peaks of type hk0, 00 l, and hkl ( h, k ≠ 0; l ≠ 0) indicate coherence lengths of approximately (6 to 7) nm within the a- b plane, the full thickness of the film along the c-axis, and (1 to 2) nm in mixed-index directions, respectively, consistent with random rotational disorder between the constituents, commonly termed turbostratic disorder in the clay literature. The intensities of 00 l- and hk0-type diffraction peaks were modeled to determine the structure of atomic planes along the c axis and the projection of the constituent structures onto the a- b plane, respectively. [ABSTRACT FROM AUTHOR]

The title compounds are prepared as thin films using the modulated elemental reactant method and their structures are characterized by synchrotron powder XRD and TEM. [ABSTRACT FROM AUTHOR]

A detailed synthetic approach, using the method of modulated elemental reactants, is described for the preparation of MX-TX(2) (M = metal, X = chalcogen, and T = transition metal) solid-state intergrowths with m and n values significantly larger than previously reported. As a specific example, we demonstrate the ability to synthesize more than 500 distinct intergrowth compounds in a single ternary system, Sn-Mo-Se. A simple method for determination of the chemical composition of the constituent layers in the precursor and product is described for cases in which both structural components contain one or more common elements. X-ray reflectivity, laboratory and synchrotron X-ray diffraction, scanning transmission electron microscopy, and high-resolution transmission electron microscopy imaging, and electron microprobe analysis provide conclusive evidence of the formation of layered intergrowths with well-defined structure and composition. The ability to access a large range of monochalcogenide thicknesses allows a size-dependent structural transition in the SnSe component to be controlled and tracked and indicates that intergrowth materials such as those described here comprise novel material systems in which size-dependent phenomena can be precisely controlled.

Telluride misfit layer compounds are reported for the first time. These compounds were synthesized using a novel approach of structurally designing a precursor that would form the desired product upon low-temperature annealing, which allows the synthesis of kinetically stable products that do not appear on the equilibrium phase diagram. Four new compounds of the [(PbTe)(1.17)]m(TiTe2)n family are reported, and their structures were examined by a variety of X-ray diffraction techniques., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)