Empirical analysis method for evaluating variable materials and scattering parameters and reduced Fermi energy of n-type bismuth telluride thermoelectric materials at room temperature

The variable materials parameter β, scattering parameter γ, and reduced Fermi energy η in n-type bismuth telluride produced by mechanical grinding followed by hot pressing were evaluated using the Fermi-Dirac statistics and a one-electron parabolic model at room temperature. The thermal conductivity κ was assumed to be a quadratic function of the electrical conductivity σ under a constant phonon thermal conductivity κ_ph and temperature. The γ and η were estimated using L and the measured Seebeck coefficient α composed of γ and η. The variational trend of L with γ was similar to that of non-degenerate semiconductors. The analytical ZT_βγη composed of β, γ, and η obtained based on the relationship between the dimensionless figure of merit ZT and η is consistent with the measured ZT_ασκ composed of α, σ, and κ. The obtained β, γ, and η indicate fundamental physical properties of thermoelectric materials alongside α, σ, and κ.