Crystal structure and Raman scattering characterization of Cu2Fe1-xCoxSnS4 chalcogenide compounds

Abstract This work reports the synthesis by solid–state reaction of Cu 2 Fe 1- x Co x SnS 4 solid solutions. Crystal structures of Cu 2 Fe 0.8 Co 0.2 SnS 4 and Cu 2 Fe 0.6 Co 0.4 SnS 4 were investigated by single crystal X-ray diffraction. Both phases crystallize in the tetragonal stannite-type structure. The volume of the tetrahedral [MS 4 ] (M = Fe, Co) presented the highest distortion, with Edge-Length Distortion (ELD) indices ∼2% from the ideal tetrahedron. The powder X-ray diffraction (XRD) patterns of Cu 2 Fe 1- x Co x SnS 4 ( x  = 0.2, 0.4, 0.6 and 0.8) has been refined by Rietveld method. No secondary phases were detected in XRD patterns. An analysis of the vibrational properties of Cu 2 Fe 1- x Co x SnS 4 was performed using Raman scattering measurements. The Raman peaks were analyzed by fitting of the spectra and subsequently identifying the vibrational modes by comparison with experimental and theoretical data from Cu 2 FeSnS 4 (CFTS) and Cu 2 CoSnS 4 (CCTS) end-members. The spectra from Cu 2 Fe 1- x Co x SnS 4 show that there is a variation in the frequency of the main A 1 peak at ∼320 cm −1 together with a decrease in the secondary mode intensity at ∼285 cm −1 . Full Width at Half Maximum (FWHM) and the intensity of the Raman peaks reflect the high crystallinity of Cu 2 Fe 1- x Co x SnS 4 solid solutions. The oxidation states of the metals were confirmed by temperature-dependent magnetization measurements performed in the antiferromagnetic Cu 2 Fe 1- x Co x SnS 4 solid solutions.