Promoted crystallisation and cationic ordering in thermoelectric Cu₂₆V₂Sn₆S₃₂ colusite by eccentric vibratory ball milling

Abstract

A pristine colusite Cu26V2Sn6S32 was successfully synthesised on a 100 g scale via mechanochemical reaction in an industrial eccentric vibratory ball mill followed by spark plasma sintering (SPS) at 873...

Ordered sphalerite derivative Cu5Sn2S7: a degenerate semiconductor with high carrier mobility in the Cu–Sn–S diagram

“…The full width at half maximum (FWHM or Γ) of the peaks is similar for the three samples and is equivalent to values observed in well-ordered sphalerite framework compounds. [53][54][55] Third, the quadrupole splitting (ΔEQ) decreases with the tin content from 1.02 mm s -1 for Cu2SnS3 to 0.77 mm s -1 for Cu5Sn2S7 (Table 3). As ΔEQ value reflects the deviation from a spherical symmetry of the charge distribution at the nucleus, it suggests that the environment of the Sn 4+ cations is less anisotropic in Cu5Sn2S7 than in Cu2SnS3.…”

“…This indicates that Sn atoms are in their +IV oxidation state 49 and in tetrahedral environment of sulfur. [50][51][52][53] Additionally, the fact that this value is unchanged indicates that the valence electron density at the tin nucleus is equivalent, 54,55 whatever the sample composition. This result highlights that Cu for Sn substitution in the Cu2+xSn1-xS3 series does not influence the oxidation state of Sn atoms.…”

Structural study and evaluation of thermoelectric properties of single-phase isocubanite (CuFe2S3) synthesized via an ultra-fast efficient microwave radiation technique

“…62 Similar observations have been recently reported in Cu2-xS, Cu2SnS3, tetrahedrite and colusite Cu26V2Sn6S32. [63][64][65][66] Simulated XRD patterns of orthorhombic and cubic cubanites (CuFe2S3) along with that of chalcopyrite (CuFeS2) patterns are depicted in Figure 1 (labeled as modelization). Experimental powder XRD patterns of isocubanite compounds synthesized by the conventional solid-liquid-vapor reaction in vacuum-sealed tubes (extracted from our previous work 41 ) and by microwave radiation (from this work) are displayed in Figure 1 (labeled as exp.…”

Long-Range Cationic Order Collapse Triggered by S/Cl Mixed-Anion Occupancy Yields Enhanced Thermoelectric Properties in Cu5Sn2S7

“…An isomer shift (IS) value of 1.58 mm s –1 was obtained in both Cu 5.133 Sn 1.866 S 7 and Cu 5.133 Sn 1.866 S 6.65 Cl 0.35 samples (Table ) from the refinement of the 119 Sn Mössbauer spectra recorded at 15 K (Figure ), indicating that Sn atoms are in their +IV oxidation state and in the tetrahedral environment of S atoms. ,,− Indeed, the presence of Cl atoms in the first coordination shell of Sn atoms must induce a modification of the valence electron density at the Sn nucleus, leading to a decrease of the IS value. ,, Hence, the identical IS value for the two sphalerite-type samples confirms that a tetrahedral environment of S atoms around the Sn atoms is retained regardless of the Cl content. This is in favor of the existence of [SnS 4 ] x clusters instead of [Sn­(S,Cl) 4 ] x clusters in the cubic sphalerite Cu 5.133 Sn 1.866 S 6.65 Cl 0.35 sample.…”