Fig. 1: Synergistically optimizing phonon and electron transport for record-high zT values.

Schematic illustration of the a super-gravity-field re-melting technology, b movement of bubbles in melts, and c reconstruction of microstructures after super-gravity-field re-melting (SGF-RM). d Process of Te evaporation causing extra holes. e Lattice thermal conductivities (κ_L) of samples before and after SGF-RM. The solid symbols present the experimental results. The black solid line represents the predicted κ_L value considering the scattering of the Umklapp process, normal process, and point defects (U + N + P). The purple solid line represents the predicted κ_L value considering the additional scattering of grain boundaries and micro-pore interfaces (U + N + P + I). The red solid line represents the predicted κ_L values considering the additional scattering of dislocations (U + N + P + I + DS). The effective medium theory (EMT)-corrected values are shown by red empty triangles. f Power factor values as a function of the Hall carrier concentration predicted by the effective mass m* = 1.05 m₀ and drift mobility µ_w = 420 cm²/V s at 300 K. g zT values of the Bi_0.48Sb_1.52Te_3.03 alloy before (BST) and after SGF-RM. Note: The sample with hand-milled powders is denoted as BST-1 after re-melting under super-gravity for 1 min. The sample with hand-milled powders is denoted as BST-10 after re-melting under super-gravity for 10 min. The sample with particle sizes between 0.6 and 1 µm is denoted as BST-S after re-melting under super-gravity for 10 min. Some reported typical results of (Bi,Sb)₂Te₃-based materials are also shown in this figure (g) ^{6,7,19,27,40,41,42}.