Pseudobinary approach to the discovery and design of copper-based sulfides
Résumé
Copper-based sulfide semiconductors with the structure based on a sphalerite-like network can provide environmentally sound solutions to thermoelectric and photovoltaic energy conversion at a low cost. In this study, we report the synthesis and characterization of a copper-based sulfide, Cu$_{30}$Ti$_6$Sb$_2$S$_{32}$, discovered within the pseudobinary Cu$_3$SbS$_4$-Cu$_4$TiS$_4$ system. This new compound crystallizes in a colusite-like cubic structure, which is characterized by "interstitial" Ti atoms forming tetrahedral-octahedral [TiS$_4$]Cu$_6$ complexes linearly arranged within the Cu-S corner-sharing matrix. The [TiS$_4$]Cu$_6$ unit arrangement distinguishes the crystal structures of Cu$_{26}$Ti$_2$Sb$_6$S$_{32}$ (isolated units, 0D linkage), Cu$_{30}$Ti$_6$Sb$_2$S$_{32}$ (chain of linked units, 1D), and Cu$_4$TiS$_4$ (plane of linked units, 2D). We emphasize the semiconducting nature and the low thermal conductivity. The electronic structure and vibrational properties are investigated by the combination of experiments and first-principles calculations. We demonstrate that a design approach based on the pseudobinary composition, here, with the generic formula (Cu$_3$SbS$_4$)$_{1-x}$) (Cu$_4$TiS$_4$)$_x$, is a fruitful direction for the discovery of new copper-based sulfides with tunable transport properties.
Domaines
Matériaux
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CuSbS_CuTiS_Hagiwara_CM_VF_revVF_arial.pdf (2.02 Mo)
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