ChemInform Abstract: Enhanced Thermoelectric Figure of Merit in Stannite—Kuramite Solid Solutions Cu_2+xFe_1‐xSnS_4‐y (x = 0—1) with Anisotropy Lowering.

Abstract

A series of polycrystalline samples of Cu2+xFe1-xSnS4-y (x = 0-1, y ≤ 0.4) are prepared by solid state reaction of stoichiometric mixtures of the elements (evacuated silica tubes, 750°C, 96 h). Structural analysis reveals that anisotropy decreases and Cu/Sn disorder increases with increasing x. Samples with x = 0.8-1 exhibit degenerate conductivity, whereas the Seebeck coefficient (S) remains relatively high, S ≈ 100μV/K for x = 0.8 at 300 K. Thermal conductivities of the solid solutions are in the range 10 -3 -10 -2 Wcm -1 K -1 , which is close to the κ value of silica. The dimensionless figure of merit (ZT) reaches 0.044 for x = 0.8 at 300 K. -(GOTO*, Y.; NAITO, F.; SATO, R.; YOSHIYASU, K.; ITOH, T.; KAMIHARA, Y.; MATOBA, M.; Inorg. Chem. 52 (2013) 17, 9861-9866, http://dx.doi.org/10.1021/ic401310c ; Dep. Appl. Phys. Physico-Inf., Keio Univ., Yokohama 223, Japan; Eng.) -J. Schramke 45-008

Hot-Injection Synthesis of Cu-Doped Cu2ZnSnSe4 Nanocrystals to Reach Thermoelectric zT of 0.70 at 450 °C

“…14,21 With increasing Cu-doping contents, the κ L at 450 °C drops from 0.55 in Cu 2 ZnSnSe 4 to 0.49 W m −1 K −1 in Cu 2.05 Zn 0.95 SnSe 4 and further down to 0.46 W m −1 K −1 in Cu 2.1 Zn 0.9 SnSe 4 . Notably, such extremely low κ L values are even smaller than that in the state-of-the-art PbTe TE materials 10.…”

Three-Fold Coordination of Copper in Sulfides: A Blockade for Hole Carrier Delocalization but a Driving Force for Ultralow Thermal Conductivity

“…In a more general way, we can affirm that all the Cu-rich sulfides, which exhibit a pure tetrahedral copper framework (i.e., group A phases with Cu/M ≥ 1 from copper-based sulfide classification), 68 are p-type conductors and can exhibit high hole carrier concentration by doping, as previously shown for Cu 5 Sn 2 S 7 , 69 Cu 22 Sn 10 S 32 , 70 Cu 3 SbS 4 , 71 Cu 2 SnS 3 , 72 and Cu 2 (Fe,Zn)SnS 4 . 73,74 In other words, these results strongly suggest that the 3-fold coordination of copper is detrimental to the generation and delocalization of hole carriers in the Cu-rich sulfides, hindering the possibility to induce the mixed valency Cu(I)/Cu(II).…”