Influence of non-stoichiometry on the electrical and magnetic properties of NiS2

Gautier, François; Krill, G.; Lapierre, M.F.; Robert, C.

doi:10.1016/0038-1098(72)90824-1

“…The usual method of preparation can give only a compound NiSz with x E 1.94. By using high-pressure synthesis (65 kbar, 1000 "C) the stoichiometric composition can be reached, and all properties of nickel disulphide vanish for x 2 2 (Gautier et al 1972). Hastings and Corliss (1970) and Adachi et al(1972) studied the magnetic properties of powdered specimens of nickel disulphide prepared by the usual methods (x N 1.94).…”

mentioning

confidence: 99%

Temperature Dependence of the Ideality Factor of Ba_1-xK_xBiO₃/Nb-doped SrTiO₃ All-Oxide-Type Schottky Junctions

Yamamoto

¹

,

Suzuki

²

,

Kawaguchi

³

et al. 1998

Jpn. J. Appl. Phys.

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Susceptibility measurements in magnetic fields up to 40 kG between 4 and 300 K on nickel disulphide samples in the composition range NiS1.91-NiSz.09 show that stoichiometric WiSz.00 is a Curie-Weiss paramagnetic substance. A sharp magnetic transition occurs at 31 K on samples which lie below stoichiometry. Below this temperature a low magneticmoment (< 1 0-1 pB/at.Ni) is obtained bysusceptibilitymeasurements. The presence of two phases is considered in order to understand what kind of transition occurs. The possible existence of a second magnetic transition at higher temperature is also discussed.

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“…Therefore, a higher Seebeck coefficient 245 does not seem to be related with the aggregation of the samples, but with the sensitivity of the 246 electronic properties (carrier concentration and type, conductivity and mobility) to stoichiometric 247 variations and crystal defects (grain boundaries and impurities). 248 The values of ρ correspond to the values reported in the literature for polycrystalline samples 249 [Gautier et al, 1972;Krill et al, 1976]. A decrease of resistivity is verified with the increase of 250 the hot-pressing temperature.…”

supporting

confidence: 72%

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Supplemental Information 11: Cell Parameters Calculation for the NiS₂ Material Hot-Pressed at 750ºC and 56 MPa for 1

0

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Vaesite, a nickel chalcogenide with NiS 2 formula, has been synthetized and studied by theoretical and experimental methods. NiS 2 was prepared by solid-state reaction under vacuum and densified by hot-pressing, at different consolidation conditions. Dense singlephase pellets (relative densities >94%) were obtained, without significant lattice distortions for different hot-pressing conditions. The thermal stability of NiS 2 was studied by thermogravimetric analysis. Both as-synthetized and hot-pressed NiS 2 have a single phase nature, although some hot-pressed samples had traces of the sulfur deficient phase, Ni 1-x S (<1%vol), due to the strong desulfurization at T > 340ºC. The electronic band structure and density of states were calculated by Density Functional Theory (DFT), indicating a metallic behavior. However, the electronic transport measurements showed ptype semiconductivity for bulk NiS 2 , verifying its characteristic behavior has a Mott insulator. The consolidation conditions strongly influence the electronic properties, with the best room-temperature Seebeck coefficient, electrical resistivity and power factor being 182µVK -1 , 2257μΩm and 14.1µWK -2 m -1 , respectively, pointing this compound as a good starting point for a new family of thermoelectric materials. PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.27825v1 | CC BY 4.0 Open Access | recAbstract 40 Vaesite, a nickel chalcogenide with NiS 2 formula, has been synthetized and studied by 41 theoretical and experimental methods. NiS 2 was prepared by solid-state reaction under vacuum 42 and densified by hot-pressing, at different consolidation conditions. Dense single-phase pellets 43 (relative densities >94%) were obtained, without significant lattice distortions for different hot-44 pressing conditions. The thermal stability of NiS 2 was studied by thermogravimetric analysis. 45 Both as-synthetized and hot-pressed NiS 2 have a single phase nature, although some hot-pressed 46 samples had traces of the sulfur deficient phase, Ni 1-x S (<1%vol), due to the strong 47 desulfurization at T > 340 ºC. The electronic band structure and density of states were calculated 48 by Density Functional Theory (DFT), indicating a metallic behavior. However, the electronic 49 transport measurements showed p-type semiconductivity for bulk NiS 2 , pointing to the presence 50 of important electron correlation effects that lead to a Mott insulator behavior. The consolidation 51 conditions strongly influence the electronic properties, with the best room-temperature Seebeck 52 coefficient, electrical resistivity and power factor being 182 µVK -1 , 2257 μΩm and 14.1 µWK -53 2 m -1 , respectively, pointing this compound as a good starting point for a new family of 54 thermoelectric materials. 55 56 57 Introduction 58The search for new, clean, energy sources, as well as the optimization of their use, has become a 59 major issue in contemporary societies. According to the European Environment Agency, current 60 conventional thermal power plants have an energy e...

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“…However, previous studies also suggested that vaesite is an intrinsic non-stoichiometric compound, with a variable metal concentration and a stable anion content. These deviations from stoichiometry, corroborated by a change of the cell parameters, have important consequences in the electrical and magnetic properties [Gautier et al, 1972;Krill et al, 1976]. NiS 2 was reported to order antiferromagnetically below T N ~50 K, which is followed by a spin reorientation at 84~30 K that leads to a week ferromagnetic ground state [Yao et al, 1996].…”

Section: Introductionmentioning

confidence: 97%

Peer Review #1 of "Preparation, thermal stability and electrical transport properties of vaesite, NiS2 (v0.1)"

2019

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Vaesite, a nickel chalcogenide with NiS 2 formula, has been synthetized and studied by theoretical and experimental methods. NiS 2 was prepared by solid-state reaction under vacuum and densified by hot-pressing, at different consolidation conditions. Dense singlephase pellets (relative densities >94%) were obtained, without significant lattice distortions for different hot-pressing conditions. The thermal stability of NiS 2 was studied by thermogravimetric analysis. Both as-synthetized and hot-pressed NiS 2 have a single phase nature, although some hot-pressed samples had traces of the sulfur deficient phase, Ni 1-x S (<1%vol), due to the strong desulfurization at T > 340ºC. The electronic band structure and density of states were calculated by Density Functional Theory (DFT), indicating a metallic behavior. However, the electronic transport measurements showed ptype semiconductivity for bulk NiS 2 , verifying its characteristic behavior has a Mott insulator. The consolidation conditions strongly influence the electronic properties, with the best room-temperature Seebeck coefficient, electrical resistivity and power factor being 182µVK-1 , 2257μΩm and 14.1µWK-2 m-1 , respectively, pointing this compound as a good starting point for a new family of thermoelectric materials.

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Influence of non-stoichiometry on the electrical and magnetic properties of NiS2

Cited by 35 publications

References 4 publications

Temperature Dependence of the Ideality Factor of Ba_1-xK_xBiO₃/Nb-doped SrTiO₃ All-Oxide-Type Schottky Junctions

Temperature Dependence of the Ideality Factor of Ba_1-xK_xBiO₃/Nb-doped SrTiO₃ All-Oxide-Type Schottky Junctions

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Peer Review #1 of "Preparation, thermal stability and electrical transport properties of vaesite, NiS2 (v0.1)"

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Influence of non-stoichiometry on the electrical and magnetic properties of NiS2

Cited by 35 publications

References 4 publications

Temperature Dependence of the Ideality Factor of Ba1-xKxBiO3/Nb-doped SrTiO3 All-Oxide-Type Schottky Junctions

Temperature Dependence of the Ideality Factor of Ba1-xKxBiO3/Nb-doped SrTiO3 All-Oxide-Type Schottky Junctions

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Peer Review #1 of "Preparation, thermal stability and electrical transport properties of vaesite, NiS2 (v0.1)"

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Temperature Dependence of the Ideality Factor of Ba_1-xK_xBiO₃/Nb-doped SrTiO₃ All-Oxide-Type Schottky Junctions

Temperature Dependence of the Ideality Factor of Ba_1-xK_xBiO₃/Nb-doped SrTiO₃ All-Oxide-Type Schottky Junctions