Local disorder investigation in NiS2-xSex using Raman and Ni K-edge x-ray absorption spectroscopies

Marini, C and Joseph, B and Caramazza, S and Capitani, F and Bendele, M and Mitrano, M and Chermisi, D and Mangialardo, S and Pal, B and Goyal, M and Iadecola, A and Mathon, O and Pascarelli, S and Sarma, DD and Postorino, P (2014) Local disorder investigation in NiS2-xSex using Raman and Ni K-edge x-ray absorption spectroscopies. In: JOURNAL OF PHYSICS-CONDENSED MATTER, 26 (45).

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Abstract

We report on Raman and Ni K-edge x-ray absorption investigations of a NiS2-xSex (with x = 0.00, 0.50/0.55, 0.60, and 1.20) pyrite family. The Ni K-edge absorption edge shows a systematic shift going from an insulating phase (x = 0.00 and 0.50) to a metallic phase (x = 0.60 and 1.20). The near-edge absorption features show a clear evolution with Se doping. The extended x-ray absorption fine structure data reveal the evolution of the local structure with Se doping which mainly governs the local disorder. We also describe the decomposition of the NiS2-xSex Raman spectra and investigate the weights of various phonon modes using Gaussian and Lorentzian profiles. The effectiveness of the fitting models in describing the data is evaluated by means of Bayes factor estimation. The Raman analysis clearly demonstrates the disorder effects due to Se alloying in describing the phonon spectra of NiS2-xSex pyrites.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICS-CONDENSED MATTER
Publisher:	IOP PUBLISHING LTD
Additional Information:	Copy right for this article belongs to the IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Keywords:	x-ray absorption spectra; metal-insulator transition; Raman spectroscopy; local disorder
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	04 Dec 2014 04:46
Last Modified:	04 Dec 2014 04:46
URI:	http://eprints.iisc.ac.in/id/eprint/50356

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