High Thermoelectric Performance and Low Lattice Thermal Conductivity in Lattice-Distorted High-Entropy Semiconductors AgMnSn_1–xPb_xSbTe₄

Abstract

We investigate the structure and thermoelectric properties of a new high-entropy solid solution system AgMnSn1–x Pb x SbTe4 (x = 0, 0.25, 0.5, 0.75, and 1), which crystallizes in the rock-salt NaCl structure with cations Ag, Mn, Sn, Pb, and Sb randomly disordered over the Na site. Our density functional theory calculations indicate that AgMnSn1–x Pb x SbTe4 exhibits complex multi-peak valence band structures, whose energy difference is lower than 0.11 eV, leading to effective band convergence and thus high density of states effective mass m* and Seebeck coefficients. As a consequence, AgMnSn0.25Pb0.75SbTe4 has a peak ZT of 1.3 at 773 K and a desirable average ZT value of 0.8 in the temperature range of 400–773 K. In addition, we propose the lattice distortion degree (i.e., δ) as an important indicator of thermoelectric performance for high-entropy materials. Specifically, with the gradual increase in δ, the lattice thermal conductivity decreases monotonically from 0.90 W m–1 K–1 for AgMnSnSbTe4 (i.e., δ = 0.205) to 0.54 W m–1 K–1 for AgMnPbSbTe4 (i.e., δ = 0.230) at 300 K. Meanwhile, the generalized material parameter B x */B 0 * and ZT increase monotonically from 1 and 0.11 for δ = 0.205 to 3.15 and 0.29 for δ = 0.230 at 300 K.

Enhancing the solubility of Mn in AgSbSe2 for high thermoelectric performance through entropy engineering

“…4C). The V a values are lower than that of SnTe, 8 GeTe, 52 PbSe, 53 PbTe 54 and CuGaTe 2 . 55 It is acknowledged that low V a often results in low κ L .…”

“…The reason for the m* increasing with the increase in x may be the change of the electron band structure caused by the increase in congurational entropy. 8,21,47 The Fourier transform infrared spectroscopy results show that alloying of MnSe can increase the band gap of AgSbSe 2 . For example, the optical band gap value increases from 0.36 eV for x = 0 to 0.48 eV for x = 0.3 (Fig.…”

“…The DOS effective mass m * of (AgSbSe 2 ) 1− x (MnSe) x is estimated using eqn (1) ( i.e. , single parabolic band (SPB) model): 8,50 …”

“…5 High thermoelectric properties of materials usually involve increasing the power factor (S 2 /r) or decreasing the k L . [6][7][8] In recent decades, with the progress of basic theory and experimental conditions, the means of thermoelectric performance optimization has been greatly developed. For example, an electronic structure modulation strategy is established by means of band convergence, 9,10 resonant level [11][12][13] and band attening [14][15][16] to enhance the power factor.…”

Toward Ultrahigh Thermoelectric Performance of Cu2SnS3‐Based Materials by Analog Alloying

“…The 𝜅 L of all the samples decreases with increasing temperature, approximately following the relationship of T −1 , which implies the reduction mainly sources from the U-process phonon-phonon scattering. [47] After analog CuInSe 2 alloying, the 𝜅 L significantly declines. Specifically, the 𝜅 L are 0.60, 0.39, [19][20][21][22][23]25,26,28] with respect to hole concentration; d) the electronic band of Cu 0.40, 0.38, and 0.37 W m −1 K −1 at 773 K for x = 0, 3, 6, 9, and 12, respectively, a drop of 38% at most.…”