High temperature neutron powder diffraction study of the Cu 12 Sb 4 S 13 and Cu 4 Sn 7 S 16 phases

Abstract

Ternary copper-containing sulfides Cu 12 Sb 4 S 13 and Cu 4 Sn 7 S 16 have attracted considerable interest since few years due to their high-efficiency conversion as absorbers for solar energy and promising thermoelectric materials. We report therein on the decomposition study of Cu 12 Sb 4 S 13 and Cu 4 Sn 7 S 16 phases using high temperature in situ neutron powder diffraction. Our results obtained at a heating rate of 2.5 K/min indicate that: (i) Cu 12 Sb 4 S 13 decomposes above ≈ 792 K into Cu 3 SbS 3 , and (ii) Cu 4 Sn 7 S 16 decomposes above ≈ 891 K into Sn 2 S 3 and a copper-rich sulfide phase of sphalerite ZnStype structure with an assumed Cu 3 SnS 4 stoichiometry. Both phase decompositions are associated to a sulfur volatilization. While the results on Cu 12 Sb 4 S 13 are in fair agreement with recent published data, the decomposition behavior of Cu 4 Sn 7 S 16 differs from other studies in terms of decomposition temperature, thermal stability and products of reaction. Finally, the crystal structure refinements from neutron powder diffraction data are reported and discussed for the Cu 4 Sn 7 S 16 and tetrahedrite Cu 12 Sb 4 S 13 phases at 300 K, and for the high temperature form of skinnerite Cu 3 SbS 3 at 843 K.

Thermoelectric properties of n-type Cu4Sn7S16-based compounds

“…Also, it is suggested that Cu2 and Cu3 atoms exhibit a large displacement, 19,21 possibly contributing to the low thermal conductivity. 20,26 As shown in Fig. 2, all the samples were identied as Cu 4 Sn 7 S 16 with the rhombohedral structure (R 3m, PDF#89-4713) and no secondary phases were found when x # 0.03 or y # 0.10.…”

Copper—antimony and copper—bismuth chalcogenides—Research opportunities and review for solar photovoltaics

“…Thermal decomposition information is available for a limited range of the compounds. The onset of degradation has been recorded as follows (see Table 2): CuSbS 2 > 400 °C 58 ; Cu 3 SbS 3 > 400 °C 64 ; Cu 3 SbS 4 > 300 °C 65 ; Cu 12 Sb 4 S 13 519 °C 40 or 543 ± 2 °C 11 ; and CuBiS 2 472 °C. 21 These relatively low temperatures, especially for the former three, may cause problems for the formation of films using methods where the substrate temperature is expected to exceed the decomposition point, e.g., close space sublimation.…”

The impact of manganese substitution on the structure and properties of tetrahedrite

“…This contrasts with the behaviour found when Cu12Sb4S13 is heated under a flowing N2 atmosphere, which leads to a complex decomposition into Cu3SbS3 from 673 K up to 753 K due to sulfur volatilisation 15. Heating of Cu12Sb4S13 under dynamic vacuum also results in decomposition due to sulfur loss 23. The substitution of Cu + (r = 0.60 Å) by Mn 2+ , which has a larger ionic radius (r = 0.66 Å), results in an expansion of the unit cell with manganese substitution (Supplementary Information).…”