Figure 5

(a) Seebeck coefficients (α) of the compounds Cu₄Sn_7.5S_16−xSe _x (x = 0.5, 1.0 and 2.0), and those for x = 0 and Cu₄Sn₇S₁₆ are presented for comparison; (b) Experimentally determined Seebeck coefficients (α) at the corresponding Hall carrier concentrations, labeled by . The solid line represents the Pisarenko relation at RT; (c) Electrical conductivities (σ) as a function of temperature for different materials (x values); (d) Power factor PF, PF = α²σ, for different materials (x values).