Preparation, thermal stability and electrical transport properties of vaesite, NiS2

Helena M Ferreira; Elsa B Lopes; José F Malta; Luís M Ferreira; Maria H Casimiro; Luís Santos; Manuel FC Pereira; Antonio Pereira Gonçalves

doi:10.7287/peerj.preprints.27825v1

Preparation, thermal stability and electrical transport properties of vaesite, NiS₂

Helena M Ferreira¹, Elsa B Lopes¹, José F Malta^1,2, Luís M Ferreira¹, Maria H Casimiro¹, Luís Santos³, Manuel FC Pereira⁴, Antonio Pereira Gonçalves ¹

1 C2TN, Departamento de Engenharia e Ciências Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Bobadela, Portugal

2 CFisUC, Departamento de Física, Universidade de Coimbra, Coimbra, Portugal

3 CQE, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal

4 CERENA, Departamento de Engenharia Civil Arquitectura e Georrecursos, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal

DOI: 10.7287/peerj.preprints.27825v1

Published: 2019-06-26
Accepted: 2019-06-26

Subject Areas: Ceramics, Electronic, Optical and Magnetic, Energy Materials, Semiconductors
Keywords: Vaesite, Chalcogenide, Hot-press, Density Functional Theory, Semiconductor, Thermoelectric

Copyright: © 2019 Ferreira et al.
Licence: This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.

Cite this article: Ferreira HM, Lopes EB, Malta JF, Ferreira LM, Casimiro MH, Santos L, Pereira MF, Pereira Gonçalves A. 2019. Preparation, thermal stability and electrical transport properties of vaesite, NiS₂. PeerJ Preprints 7:e27825v1 https://doi.org/10.7287/peerj.preprints.27825v1

Abstract

Vaesite, a nickel chalcogenide with NiS₂ formula, has been synthetized and studied by theoretical and experimental methods. NiS₂ was prepared by solid-state reaction under vacuum and densified by hot-pressing, at different consolidation conditions. Dense single-phase pellets (relative densities >94%) were obtained, without significant lattice distortions for different hot-pressing conditions. The thermal stability of NiS₂ was studied by thermogravimetric analysis. Both as-synthetized and hot-pressed NiS₂ have a single phase nature, although some hot-pressed samples had traces of the sulfur deficient phase, Ni_1-xS (<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 p-type semiconductivity for bulk NiS₂, 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^-2m^-1, respectively, pointing this compound as a good starting point for a new family of thermoelectric materials.

Author Comment

This is a submission to PeerJ Materials Science for review.

Supplemental Information

Powder X-ray diffraction data of the NiS2 material hot-pressed at 750ºC and 56 MPa for 1.5 h

Powder X-ray diffraction data of the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h

Powder X-ray diffraction data of the NiS2 material hot-pressed at 700ºC and 56 MPa for 1.5 h

Powder X-ray diffraction data of the NiS2 as-synthesized material

Thermogravimetric analysis results of the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h

Thermogravimetric analysis results of the NiS2 as-synthesized material

Raman spectrum of the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h

Porosity analysis results of the NiS2 materials

Apparent density results of the NiS2 materials

Cell parameters calculation for the NiS2 as-synthesized material

Cell parameters calculation for the NiS2 material hot-pressed at 750ºC and 56 MPa for 1.5 h

Cell parameters calculation for the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h

Cell parameters calculation for the NiS2 material hot-pressed at 700ºC and 56 MPa for 1.5 h

EDS results of the NiS2 material hot-pressed at 700ºC and 56 MPa for 1.5 h (area 1)

EDS results of the NiS2 material hot-pressed at 700ºC and 56 MPa for 1.5 h (area 2)

EDS results of the NiS2 material hot-pressed at 700ºC and 56 MPa for 1.5 h (area 3)

EDS results of the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h (area 1)

EDS results of the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h (area 2)

EDS results of the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h (area 3)

EDS results of the NiS2 material hot-pressed at 750ºC and 56 MPa for 1.5 h

Seebeck coefficient data of the NiS2 material hot-pressed at 700ºC and 56 MPa for 1.5 h

Seebeck coefficient data of the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h

Seebeck coefficient data of the NiS2 material hot-pressed at 750ºC and 56 MPa for 1.5 h

Electrical resistivity data of the NiS2 material hot-pressed at 700ºC and 56 MPa for 1.5 h

Electrical resistivity data of the NiS2 material hot-pressed at 720ºC and 56 MPa for 1.5 h

Electrical resistivity data of the NiS2 material hot-pressed at 750ºC and 56 MPa for 1.5 h

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Powder X-ray diffraction data of the NiS₂ material hot-pressed at 750ºC and 56 MPa for 1.5 h

Powder X-ray diffraction data of the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h

Powder X-ray diffraction data of the NiS₂ material hot-pressed at 700ºC and 56 MPa for 1.5 h

Powder X-ray diffraction data of the NiS₂ as-synthesized material

Thermogravimetric analysis results of the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h

Thermogravimetric analysis results of the NiS₂ as-synthesized material

Raman spectrum of the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h

Porosity analysis results of the NiS₂ materials

Apparent density results of the NiS₂ materials

Cell parameters calculation for the NiS₂ as-synthesized material

Cell parameters calculation for the NiS₂ material hot-pressed at 750ºC and 56 MPa for 1.5 h

Cell parameters calculation for the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h

Cell parameters calculation for the NiS₂ material hot-pressed at 700ºC and 56 MPa for 1.5 h

EDS results of the NiS₂ material hot-pressed at 700ºC and 56 MPa for 1.5 h (area 1)

EDS results of the NiS₂ material hot-pressed at 700ºC and 56 MPa for 1.5 h (area 2)

EDS results of the NiS₂ material hot-pressed at 700ºC and 56 MPa for 1.5 h (area 3)

EDS results of the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h (area 1)

EDS results of the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h (area 2)

EDS results of the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h (area 3)

Seebeck coefficient data of the NiS₂ material hot-pressed at 700ºC and 56 MPa for 1.5 h

Seebeck coefficient data of the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h

Seebeck coefficient data of the NiS₂ material hot-pressed at 750ºC and 56 MPa for 1.5 h

Electrical resistivity data of the NiS₂ material hot-pressed at 700ºC and 56 MPa for 1.5 h

Electrical resistivity data of the NiS₂ material hot-pressed at 720ºC and 56 MPa for 1.5 h

Electrical resistivity data of the NiS₂ material hot-pressed at 750ºC and 56 MPa for 1.5 h