. Temperature-dependent (a) total thermal conductivities(κ_tot) and (b) lattice thermal conductivities (κ_lat) of SnTe_1-2xS_xSe_x (x = 0, 0.05, 0.1, and 0.15) samples

. Room temperature (a) powder XRD patterns, (b) lattice parameter of SnTe_1-2xS_xSe_x (x=0, 0.05, 0.1, and 0.15) samples

. Temperature dependent (a) electrical conductivity and (b) Seebeck coefficient of SnTe_1-2xS_xSe_x (x=0, 0.05, 0.1, and 0.15) samples

. Temperature-dependent (a) total thermal conductivities(κ_tot) and (b) lattice thermal conductivities (κ_lat) of Sn_1-yIn_yTe_0.7S_0.15Se_0.15 (y=0, 0.0025, 0.005, 0.01, and 0.015) samples

. Room temperature (a) powder XRD patterns, (b) lattice parameter a, (c) Hall carrier density N_p, and (d) carrier mobility μ of Sn_1-yIn_yTe_0.7S_0.15Se_0.15 (y=0, 0.0025, 0.005, 0.01, and 0.015) samples

. Microstructures of Sn_0.99In_0.01Te_0.7S_0.15Se_0.15
(a) Medium-magnification TEM and (b) low-magnification images show the presence of nanoscale secondary phase; The inset in (a) is the SAED pattern along [004]; (c) HRTEM image focusing on the secondary phase with distorted connection between the precipitate and the matrix; The top-right and bottom-right insets are the respective FFT images showing lattice distortion between them; (d) the same TEM image with (c) showing the IFFT image (the bottom-right inset) of the selected region reflecting lattice distortion; and strain maps reflect high strain states inside (e) and around (f) the precipitates

. Temperature dependent heat diffusivity of Sn_1-yIn_yTe_0.7S_0.15Se_0.15 (y=0, 0.0025, 0.005, 0.01, and 0.015) samples

. Temperature dependent thermoelectric properties: (a) electrical conductivity σ, (b) the Seebeck coefficients S,(c) the power factors S²σ, and (d) ZT values for Sn_1-yIn_yTe_0.7S_0.15Se_0.15 (y=0, 0.0025, 0.005, 0.01, and 0.015) samples

. Room temperature Pisarenko plot for Sn_1-yIn_yTe_0.7(SeS)_0.15 (y=0,0.0025,0.005,0.01,0.015). The solid curve is experted from Zhang^[18]

Table 1. The density ρ, hole concentration n, mobility μ, electrical conductivity σ, Seebeck coefficient S, and power factor S²σ for Sn_1-yIn_yTe_0.7S_0.15Se_0.15 (y=0, 0.0025, 0.005, 0.01, and 0.015) samples at room temperature