Low temperature thermoelectric properties of Cu intercalated TiSe2: a charge density wave material

Bhatt, Ranu; Basu, Ranita; Bhattacharya, Shovit; Singh, Ajay; Aswal, D. K.; Gupta, S. K.; Okram, G. S.; Ganesan, V.; Venkateshwarlu, D.; Sürgers, Christoph; Navaneethan, M.; Hayakawa, Y.

doi:10.1007/s00339-012-7536-8

Cited by 25 publications

(31 citation statements)

References 20 publications

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“…If electrons are indeed transferred from the rocksalt to the dichalcogenide to fill lower energy states, this results in partially filled bands in both constituents, with the higher mobility carriers in the dichalcogenide layer responsible for the transport properties. This proposed mechanism of conduction explains the change in sign of both measured Hall and Seebeck coefficients for a number of misfit layered compounds when compared to the pristine bulk dichalcogenides and their intercalates [ 45 , 63 , 64 , 65 , 66 ]. This suggests that selection of the two proper constituents could provide a method of optimizing the carrier concentration to maximize the power factor.…”

Section: Misfit Layer Compoundsmentioning

confidence: 91%

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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Section: Misfit Layer Compoundsmentioning

confidence: 91%

Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

et al. 2015

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“…Unfortunately, “pure” TiS 2 13,21−24 and TiSe 2 25 have insufficient thermoelectric efficiency for application. So far, a series of works aimed at improving the thermoelectric properties of TiS 2 and TiSe 2 by substitution in cationic 16,21,22 or anionic 26,27 sublattices, as well as intercalating them by metal atoms, 22,24−26 compounds, 21,22,24 or preparation of hybrid structures based on TiS 2 28 . However, these attempts did not significantly improve the thermoelectric efficiency of material.…”

Section: Introductionmentioning

confidence: 99%

Improved thermoelectric properties of layered Ti₁₋_xNb_xS₂₋_ySe_y solid solutions

et al. 2020

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The thermoelectric properties of a series of the polycrystalline samples of titanium dichalcogenides with partial substitution of Ti for Nb and S for Se were investigated. It was found that sintering of the samples improved the thermoelectric efficiency (ZT), and the maximum ZT was achieved at sintering temperature of 600°C. A further increase in the sintering temperature (850°C and 950°C) led to the recrystallization of the samples, as a result, the Seebeck coefficient sharply decreased and electrical conductivity dramatically increased. The temperature dependences of electrical conductivity σ(T) in the temperature range from 4.2 to 300 K and Seebeck coefficient S(T) in the temperature range from 77 to 300 K were investigated in order to determine the nature of the observed improvements in thermoelectric properties due to double substitutions and sintering. Two‐dimensionalization of electron transport properties of Ti1−xNbxS2−ySey solid solutions was found. The Fermi energy EF2D was estimated using the temperature dependences of Seebeck coefficient. The relationship between the Fermi energy EF2D and figure of merit ZT was established. The effect of sintering on parameters σ(T), S(T), charge carrier concentration (n2D), mobility (µ), and thermal conductivity (k) was found. The optimal value of Fermi energy EF2D in terms of figure of merit ZT = 0.31 at room temperature (T = 300 K) was found for Ti0.98Nb0.02S1.3Se0.7 sample sintered at 600°C.

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“…TiS 2 and TiSe 2 have anomalously large Seebeck coefficients, which has been attributed to an unusually large phonon drag effect 10. While the binary compounds have thermal conductivities that are too large for them to be effective thermoelectric materials, recent reports have shown that inserting cations or incorporating structural layers into the van der Waal gaps reduces thermal conductivity while preserving the unusual electrical properties 5,6,11,12. For the misfit layered TiS 2 containing compounds, the group of Koumoto has shown that changing the identity of the intercalated rock salt structure changes the amount of charge transfer 5.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2014

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Keywords: Layered compounds / Thin films / Electronic structure / Thermoelectric materials / Charge transfer (SnSe) 1.2 TiSe 2 was found to self-assemble from a precursor containing modulated layers of Sn-Se and Ti-Se over a surprisingly large range of layer thicknesses and compositions. The constituent lattices form an alternating layer superstructure with rotational disorder present between the layers. This compound was found to have the highest Seebeck coefficient measured for analogous TiX 2 containing misfit layered compounds to date, suggesting potential for [a]83 low-temperature thermoelectric applications. Electrical characterization suggests that electrons transferred from SnSe to TiSe 2 are responsible for the higher carrier concentration observed relative to bulk TiSe 2 . The transfer of charge from one constituent to the other may provide a mechanism for doping layered dichalcogenides for various applications without negatively affecting carrier mobility.

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Low temperature thermoelectric properties of Cu intercalated TiSe2: a charge density wave material

Cited by 25 publications

References 20 publications

Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

Improved thermoelectric properties of layered Ti₁₋_xNb_xS₂₋_ySe_y solid solutions

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

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Low temperature thermoelectric properties of Cu intercalated TiSe2: a charge density wave material

Cited by 25 publications

References 20 publications

Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites

Improved thermoelectric properties of layered Ti1−xNbxS2−ySey solid solutions

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

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Improved thermoelectric properties of layered Ti₁₋_xNb_xS₂₋_ySe_y solid solutions

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