The Synthesis, Structure, and Electrical Characterization of (SnSe)<sub>1.2</sub>TiSe<sub>2</sub>

Merrill, Devin R.; Moore, Daniel B.; Ditto, Jeffrey; Sutherland, Duncan R.; Falmbigl, Matthias; Winkler, Markus; Pernau, Hans‐Fridtjof; Johnson, David C.

doi:10.1002/ejic.201402814

Cited by 33 publications

(93 citation statements)

References 40 publications

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“…Using the relationship derived by Parratt and estimating that Kiessig fringes are no longer visible at approximately 12 o 2θ, we estimate the average roughness of the films to be near 1.2 Å. 35,36 While the variation in the position of the reflections and therefore unit cell sizes is small, there are pronounced changes in the relative intensities of reflections in the diffraction patterns. Since the diffracted intensity in these specular XRD patterns is proportional to the Fourier transform of the electron density profile along the axial direction, the variation in relative intensities reflects the different stacking sequence of the constituents in the isomeric intergrowths.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Thermal Properties of Solid-State Structural Isomers: Ordered Intergrowths of SnSe and MoSe₂

et al. 2015

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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 deposited and annealing the precursors to self-assemble the targeted compound, all six 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, [(SnSe)1.05]2(MoSe2)1[(SnSe)1.05]1(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.

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Section: Methodsmentioning

confidence: 99%

Synthesis and Thermal Properties of Solid-State Structural Isomers: Ordered Intergrowths of SnSe and MoSe₂

et al. 2015

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“…As with the thermodynamically stable misfit compounds, however, materials based on TiSe 2 have shown to produce carrier concentrations on the order of 10 21 cm −3 , with high Seebeck coefficients and in-plane resistivity values on the order of 10 −5 Ωm. To date, (SnSe) 1.2 TiSe 2 , (PbSe) 1+δ (TiSe 2 ) n (n = 1, 2) and (BiSe) 1.15 TiSe 2 have all been reported [77,86,88,92]. For TiSe 2 based compounds, the only direct comparison between a ferecrystal and a misfit compound is for [(PbSe)] 1.16 (TiSe 2 ) 2 [65,86].…”

Section: Ferecrystalsmentioning

confidence: 99%

Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

et al. 2015

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A basic summary of thermoelectric principles is presented in a historical context, following the evolution of the field from initial discovery to modern day high-zT materials. A specific focus is placed on nanocomposite materials as a means to solve the challenges presented by the contradictory material requirements necessary for efficient thermal energy harvest. Misfit layer compounds are highlighted as an example of a highly ordered anisotropic nanocomposite system. Their layered structure provides the opportunity to use multiple constituents for improved thermoelectric performance, through both enhanced phonon scattering at interfaces and through electronic interactions between the constituents. Recently, a class of metastable, turbostratically-disordered misfit layer compounds has been synthesized using a kinetically controlled approach with low reaction temperatures. The kinetically stabilized structures can be prepared with a variety of constituent ratios and layering schemes, providing an avenue to systematically understand structure-function relationships not possible in the thermodynamic compounds. We summarize the work that has been done to date on these materials. The observed turbostratic disorder has been shown to result in extremely low cross plane thermal conductivity and in plane thermal conductivities that are also very small, suggesting the structural motif could be attractive as thermoelectric materials if the power factor could be improved. The first 10 compounds in the [(PbSe)1+δ]m(TiSe2)n family (m, n ≤ 3) are reported as a case study. As n increases, the magnitude of the Seebeck coefficient is significantly increased without a simultaneous decrease in the in-plane electrical conductivity, resulting in an improved thermoelectric power factor.

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“…This system was chosen because previous investigations of (Pb x Sn 1− x Se) 1 (TiSe 2 ) 1 showed that a solid solution could be formed over the entire composition range, even though the bulk phase diagram of Pb x Sn 1− x Se shows a miscibility gap . Previous investigations also determined that both SnSe and PbSe form distorted rock salt structures when layered with TiSe 2 , and that the structures of the SnSe and PbSe both change as their layer thicknesses are increased . Herein, we show that, while surface segregation does not occur in bilayers of Pb x Sn 1− x Se alloys, when the thickness is larger than a bilayer a segregation of Pb to the interface is apparent using several different experimental techniques.…”

Section: Figurementioning

confidence: 64%

Interface‐Driven Structural Distortions and Composition Segregation in Two‐Dimensional Heterostructures

et al. 2017

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The discovery of emergent phenomena in 2D materials has sparked substantial researche fforts in the materials community.Asignificant experimental challenge for this field is exerting atomistic control over the structure and composition of the constituent 2D layers and understanding howt he interactions between layers drive both structure and properties.W hile no segregation for single bilayers was observed, segregation of Pb to the surface of three bilayer thickP bSe-SnSe alloyl ayers was discovered within [(Pb x Sn 1Àx Se) 1+d ] n (TiSe 2 ) 1 heterostructures using electron microscopy. This segregation is thermodynamically favored to occur when Pb x Sn 1Àx Se layers are interdigitated with TiSe 2 monolayers.D FT calculations indicate that the observed segregation depends on what is adjacent to the Pb x Sn 1Àx Se layers.T he interplay between interface-and volume-free energies controls both the structure and composition of the constituent layers,w hich can be tuned using layer thickness.

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The Synthesis, Structure, and Electrical Characterization of (SnSe)_1.2TiSe₂

Cited by 33 publications

References 40 publications

Synthesis and Thermal Properties of Solid-State Structural Isomers: Ordered Intergrowths of SnSe and MoSe₂

Synthesis and Thermal Properties of Solid-State Structural Isomers: Ordered Intergrowths of SnSe and MoSe₂

Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

Interface‐Driven Structural Distortions and Composition Segregation in Two‐Dimensional Heterostructures

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The Synthesis, Structure, and Electrical Characterization of (SnSe)1.2TiSe2

Cited by 33 publications

References 40 publications

Synthesis and Thermal Properties of Solid-State Structural Isomers: Ordered Intergrowths of SnSe and MoSe2

Synthesis and Thermal Properties of Solid-State Structural Isomers: Ordered Intergrowths of SnSe and MoSe2

Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

Interface‐Driven Structural Distortions and Composition Segregation in Two‐Dimensional Heterostructures

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The Synthesis, Structure, and Electrical Characterization of (SnSe)_1.2TiSe₂

Synthesis and Thermal Properties of Solid-State Structural Isomers: Ordered Intergrowths of SnSe and MoSe₂

Synthesis and Thermal Properties of Solid-State Structural Isomers: Ordered Intergrowths of SnSe and MoSe₂