The pressure dependences of TiS<sub>2</sub>and TiSe<sub>2</sub>band structures

Benesh, G. A.; Woolley, A M; Umrigar, C. J.

doi:10.1088/0022-3719/18/8/007

Cited by 58 publications

(27 citation statements)

References 34 publications

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“…To date, for instance, whether it is a semiconductor or semimetal has not been clarified. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Through measurements of the Hall coefficient, Seebeck coefficient, and resistivity as a function of pressure, Klipstein and Friend 2 found that the band overlap between S 3p states and Ti 3d states increased at a rate of 4.5 meV/kbar, and concluded that TiS 2 is a semiconductor with a gap of 0.18 ± 0.06 eV. The optical measurements of Greenway and Nische 3 indicated that TiS 2 is a semiconductor with a gap of 1 eV to 2 eV.…”

Section: Introductionmentioning

confidence: 99%

“…On the contrary, some theoretical calculations indicate that TiS 2 is a semimetal. Lately, Benesh et al 8 obtained a semimetallic ground state for TiS 2 by using the linearized augmented plane wave (LAPW) method as a function of pressure. Similarly, band calculations based on the augmented spherical wave (ASW) method by Fang et al, 9 the linear muffin-tin orbital (LMTO) method by Wu et al, [10][11][12] and the full-potential (FP)-LAPW method 13,14 showed that TiS 2 possessed a semimetallic ground state.…”

Section: Introductionmentioning

confidence: 99%

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Thermoelectric Properties of Co-Doped TiS2

Zhang

Qin

Xin

et al. 2011

Journal of Elec Materi

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The thermoelectric properties of cobalt-doped compounds Co x Ti 1Àx S 2 (0 £ x £ 0.3) prepared by solid-state reaction were investigated from 5 K to 310 K. It was found that the electric resistivity q and absolute thermopower |S| for all the doped compounds decreased significantly with increasing Co content over the whole temperature range investigated. The increased lattice thermal conductivity of the doped compounds would imply enhancement of the acoustic velocity. Moreover, the ZT value of the doped compounds was improved over the whole temperature range investigated, and specifically reached 0.03 at 310 K for Co 0.3 Ti 0.7 S 2 , being about 66% larger than that of TiS 2 . INTRODUCTIONTiS 2 has an anisotropic structure with a trigonal space group, P " 3m1. It is known to exist in two polytypes (1T, 2H) with octahedral and trigonalprismatic coordinations, respectively. The main difference between the 1T-TiS 2 and 2H-TiS 2 layers is the type of local coordination of the metal: octahedral (1T) versus trigonal-prismatic (2H) 1 (Fig. 1). The most stable form of TiS 2 (1T-TiS 2 , crystallizing in a layered CdI 2 -like structure) consists of sheets of face-sharing TiS 6 octahedra forming S-Ti-S sandwich layers, where a Ti sheet is sandwiched between two sulfur sheets. Atoms within S-Ti-S sheets are bound by strong covalent interactions, whereas bonding between the layers is determined by weak, van der Waals forces.Although the structure of TiS 2 is quite simple, the nature of the electronic structure of layered TiS 2 has been in dispute over the past decades. To date, for instance, whether it is a semiconductor or semimetal has not been clarified. 2-16 Through measurements of the Hall coefficient, Seebeck coefficient, and resistivity as a function of pressure, Klipstein and Friend 2 found that the band overlap between S 3p states and Ti 3d states increased at a rate of 4.5 meV/kbar, and concluded that TiS 2 is a semiconductor with a gap of 0.18 ± 0.06 eV. The optical measurements of Greenway and Nische 3 indicated that TiS 2 is a semiconductor with a gap of 1 eV to 2 eV. Chen et al. 4 and Barry et al. 5 reported a band gap of about 0.3 eV from angle-resolved photoemission studies (ARPS). Photoemission experiments by Shepherd and Williams 6 indicate a band gap of less than 0.5 eV, and calculations using the pseudopotential (PP) method 7 indicated that TiS 2 is a semiconductor with an indirect band gap of about 2 eV. On the contrary, some theoretical calculations indicate that TiS 2 is a semimetal. Lately, Benesh et al. 8 obtained a semimetallic ground state for TiS 2 by using the linearized augmented plane wave (LAPW) method as a function of pressure. Similarly, band calculations based on the augmented spherical wave (ASW) method by Fang et al., 9 the linear muffin-tin orbital (LMTO) method by Wu et al., [10][11][12] and the full-potential (FP)-LAPW method 13,14 showed that TiS 2 possessed a semimetallic ground state. Meanwhile, many experiments 15,16 have indicated that the electrical resistivity of TiS 2 almost excl...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermoelectric Properties of Co-Doped TiS2

Zhang

Qin

Xin

et al. 2011

Journal of Elec Materi

View full text Add to dashboard Cite

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“…The band gap of TiS 2 was investigated many times both experimentally [57][58][59][60][61][62][63][64][65] and theoretically [5,11,[66][67][68][69][70][71][72][73][74]. Experimental studies suggest that TiS 2 is a semiconductor with a small indirect band gap between 0.18 eV [63] and 0.56 eV [65].…”

Section: Band Structurementioning

confidence: 99%

Density Functional Theory Evaluated for Structural and Electronic Properties of 1T-Li _x TiS₂ and Lithium Ion Migration in 1T-Li_0.94TiS₂

Werth

Volgmann

Islam

et al. 2017

Zeitschrift Für Physikalische Chemie

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Abstract:In many applications it has been found that the standard generalized gradient approximation (GGA) does not accurately describe weak chemical bond and electronic properties of solids containing transition metals. In this work, we have considered the intercalation material 1T-Li x TiS 2 (0 ≤ x ≤ 1) as a model system for the evaluation of the accuracy of GGA and corrected GGA with reference to the availabile experimental data. The influence of two different dispersion corrections (D3 and D-TS) and an on-site Coulomb repulsion term (GGA + U) on the calculated structural and electronic properties is tested. All calculations are based on the Perdew-Burke-Ernzerhof (PBE) functional. An effective U value of 3.5 eV is used for titanium. The deviation of the calculated lattice parameter c for TiS 2 from experiment is reduced from 14 % with standard PBE to −2 % with PBE + U and Grimme's D3 dispersion correction. 1T-TiS 2 has a metallic ground state at PBE level whereas PBE + U predicts an indirect gap of 0.19 eV in agreement with experiment. The 7 Li chemical shift and quadrupole coupling constants are in reasonable agreement with the experimental data only for PBE + U-D3. An activation energy of 0.4 eV is calculated with PBE + U-D3 for lithium migration via a tetrahedral interstitial site. This result is closer to experimental values than the migration barriers previously obtained at LDA level. The proposed method PBE + U-D3 gives a reasonable description of structural and electronic properties of 1T-Li x TiS 2 in the whole range 0 ≤ x ≤ 1.

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“…Up to now, for instance, whether it is semiconductor or semimetal has not been clarified [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Through the measurements of the Hall coefficient, Seebeck coefficient and resistivity as a function of pressure, Klipstein and Friend [2] found that the band overlap between S 3p states and Ti 3d states increased at a rate of 4.5 meV/kbar, and concluded that TiS 2 is a semiconductor with a gap of 0.18 ± 0.06 eV.…”

Section: Introductionmentioning

confidence: 99%

The transport and thermoelectric properties of Cd doped compounds (CdxTi1−x)1+yS2

Zhang

Qin

et al. 2009

Journal of Alloys and Compounds

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The pressure dependences of TiS₂and TiSe₂band structures

Cited by 58 publications

References 34 publications

Thermoelectric Properties of Co-Doped TiS2

Thermoelectric Properties of Co-Doped TiS2

Density Functional Theory Evaluated for Structural and Electronic Properties of 1T-Li _x TiS₂ and Lithium Ion Migration in 1T-Li_0.94TiS₂

The transport and thermoelectric properties of Cd doped compounds (CdxTi1−x)1+yS2

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The pressure dependences of TiS2and TiSe2band structures

Cited by 58 publications

References 34 publications

Thermoelectric Properties of Co-Doped TiS2

Thermoelectric Properties of Co-Doped TiS2

Density Functional Theory Evaluated for Structural and Electronic Properties of 1T-Li x TiS2 and Lithium Ion Migration in 1T-Li0.94TiS2

The transport and thermoelectric properties of Cd doped compounds (CdxTi1−x)1+yS2

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The pressure dependences of TiS₂and TiSe₂band structures

Density Functional Theory Evaluated for Structural and Electronic Properties of 1T-Li _x TiS₂ and Lithium Ion Migration in 1T-Li_0.94TiS₂