title: Local disorder investigation in NiS(2-x)Se(x) using Raman and Ni K-edge x-ray absorption spectroscopies.
abstract: We report on Raman and Ni K-edge x-ray absorption investigations of a NiS(2-x)Se(x) (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 NiS(2-x)Se(x) 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 NiS(2-x)Se(x) pyrites.
authors.affiliation: CELLS-ALBA, Carretera B.P. 1413, Cerdanyola del Vallès, 08290, Barcelona, Spain. ESRF-The European Synchrotron, 71 avenue des Martyrs, 38000 Grenoble, France.
authors.forename: C
authors.initials: C
authors.lastname: Marini
authors.forename: B
authors.initials: B
authors.lastname: Joseph
authors.forename: S
authors.initials: S
authors.lastname: Caramazza
authors.forename: F
authors.initials: F
authors.lastname: Capitani
authors.forename: M
authors.initials: M
authors.lastname: Bendele
authors.forename: M
authors.initials: M
authors.lastname: Mitrano
authors.forename: D
authors.initials: D
authors.lastname: Chermisi
authors.forename: S
authors.initials: S
authors.lastname: Mangialardo
authors.forename: B
authors.initials: B
authors.lastname: Pal
authors.forename: M
authors.initials: M
authors.lastname: Goyal
authors.forename: A
authors.initials: A
authors.lastname: Iadecola
authors.forename: O
authors.initials: O
authors.lastname: Mathon
authors.forename: S
authors.initials: S
authors.lastname: Pascarelli
authors.forename: D D
authors.initials: DD
authors.lastname: Sarma
authors.forename: P
authors.initials: P
authors.lastname: Postorino