Stoichiometry, structure, and physical properties of niobium disulfide

Fisher, Wayne G.; Sienko, M. J.

doi:10.1021/ic50203a009

Cited by 133 publications

(101 citation statements)

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“…both based on post-transition metal atoms present in one-third of the available trigonal-antiprismatic holes between NbS2 or TaS2 sandwiches which have Nb or Ta in trigonal-prismatic coordination by sulfur. The NbS2 and TaS2 sublattices are similar to those of the pure dichalcogenides 2H-NbS2 (a = 3.324, c = 11.95/~ [3]), and 2H-TaS2 (a= 3.314, c ----12.097 & [4]), the space group being P63/mmc). Due to the occupation by Sn and Pb of only onethird of the available sites, the a axis is v/3 times that of Nb and Ta dichalcogenides and the c axes are expanded by about 2.5 A.…”

Section: Introductionmentioning

confidence: 60%

Crystal structure and band structure calculations of and

Fang

Wiegers

Meetsma

et al. 1996

Physica B: Condensed Matter

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Crystal structure and band structure calculations of Pb1/3TaS2 and Sn1/3NbS2 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Fang, C. M., Wiegers, G. A., Meetsma, A., de Groot, R. A., & Haas, C. (1996). Crystal structure and band structure calculations of Pb1/3TaS2 and Sn1/3NbS2. Physica B, 226(4), 259 -267. DOI: 10.1016/0921-4526(96)00271-2 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. AbstractThe crystal structures of Pb~/3TaS2 and Sn~/3NbS2 were determined using single-crystal X-ray diffraction. The space group is P6322 and the unit cell dimensions are: a = 5.759(1 ), c = 14.813(1)A and a = 5.778(1), c = 14.394(1 )/~, for the Pb and Sn compounds, respectively. The post-transition metal atoms occupy one-third of the trigonal-antiprismatic holes between sandwiches NbS2 and TaS2. The Nb and Ta atoms are in trigonal-prismatic coordination by sulfur atoms. The stacking of sandwiches is the same as in 2H disulfides. The arrangement of the post-transition metal atoms is different for the two compounds. A bond valence calculation showed Sn and Pb to be divalent.Ab initio band structure calculations were performed for Snl/3NbS2 using the localized spherical wave method, and for Pbl/3TaS2 with the augmented spherical wave method with spin-orbital interactions included. The calculations show that the rigid band model is approximately valid for the electronic structures; the main difference with those of 2H-NbS2 and 2H-TaS2 being the presence of Sn 5s and 5p (Pb 6s and 6p) bands and a larger S 3p/Nb(Ta) 4d (5d) gap in the intercalates (l.0eV for Snl/3NbS2, 1.3 eV for Pbl/3TaS2). The Sn 5s (Pb 6s) bands are at the bottom (bonding) and top (antibonding) of the valence bands which range from about -7 to about 0 eV. The conduction bands are composed of Nb 4d:2 or Ta 5d~2 orbitals hybridized with S 3p. These bands are filled to about 0.3 holes per Nb (Ta), corresponding to a donation of two electrons per Sn (Pb). I. IntroductionDiSalvo et al. [1] were the first to study the compounds MxTaS2 with M a post-transition element (Ga, In, Ge, Sn, Pb); they used X-ray powder methods for characterization. Eppinga and Wiegers [2] synthesized, besides the compounds already found by DiSalvo et al.

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Section: Introductionmentioning

confidence: 60%

Crystal structure and band structure calculations of and

Fang

Wiegers

Meetsma

et al. 1996

Physica B: Condensed Matter

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“…They were grown as described in Ref. 35, and have a hexagonal shape, with lateral dimensions of about 150 μm and thickness around 30 μm. We loaded them into a pressure cell made from a copper-beryllium alloy, within the sample space delimited by the diamond anvils, which are 0.7 mm in culet diameter, and a gasket made from a NiMo alloy.…”

Section: Methodsmentioning

confidence: 99%

Pressure dependence of superconducting critical temperature and upper critical field of 2H-NbS2

et al. 2013

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We present measurements of the superconducting critical temperature T c and upper critical field H c2 as a function of pressure in the transition metal dichalcogenide 2H -NbS 2 up to 20 GPa. We observe that T c increases smoothly from 6 K at ambient pressure to about 8.9 K at 20 GPa. This range of increase is comparable to the one found previously in 2H -NbSe 2 . The temperature dependence of the upper critical field H c2 (T ) of 2H -NbS 2 varies considerably when increasing the pressure. At low pressures, H c2 (0) decreases, and at higher pressures both T c and H c2 (0) increase simultaneously. This points out that there are pressure induced changes of the Fermi surface, which we analyze in terms of a simplified two-band approach.

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“…• C) under high S vapour pressure, any excess Nb (at low S vapour pressure) results in the metal-rich 3R phase [13]. The stoichiometry limit for single phase 3R-Nb 1+x S 2 depends on the preparation temperature, and a minimum of x = .03 has been reported at 650…”

Section: Introductionmentioning

confidence: 99%

Low-temperature resistance minimum in non-superconducting 3R-Nb_1+xS₂and 3R-Ga_xNbS₂

Niazi¹,

Rastogi²

2001

J. Phys.: Condens. Matter

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We report the structural and electron transport properties of 3R-Nb1+xS2 (x ≥ .07) and 3R-GaxNbS2 (.1 ≤ x ≤ .33) prepared as polycrystalline pellets as well as single crystals grown by vapour transport. We observe a resistance minimum in these compounds between 20-60 K, with the Tmin proportional to x. The resistance scales as ρ/ρmin(T /Tmin) between .2 < T /Tmin < 2 for different phases with x ≤ .25 whose resistivity differs by an order of magnitude. Powder X-ray diffraction (XRD) also shows progressively increasing intensity of superlattice lines with cation concentration. The thermopower changes sign around the resistance minimum. The explanation of the resistance minimum and the simultaneous rapid suppression of superconductivity is sought in e-e scattering effects in the presence of cation disorder in these narrow band anisotropic materials.

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Stoichiometry, structure, and physical properties of niobium disulfide

Cited by 133 publications

References 2 publications

Crystal structure and band structure calculations of and

Crystal structure and band structure calculations of and

Pressure dependence of superconducting critical temperature and upper critical field of 2H-NbS2

Low-temperature resistance minimum in non-superconducting 3R-Nb_1+xS₂and 3R-Ga_xNbS₂

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Stoichiometry, structure, and physical properties of niobium disulfide

Cited by 133 publications

References 2 publications

Crystal structure and band structure calculations of and

Crystal structure and band structure calculations of and

Pressure dependence of superconducting critical temperature and upper critical field of 2H-NbS2

Low-temperature resistance minimum in non-superconducting 3R-Nb1+xS2and 3R-GaxNbS2

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Low-temperature resistance minimum in non-superconducting 3R-Nb_1+xS₂and 3R-Ga_xNbS₂