Experimental determination of the liquidus projection in the Cu-Sb-Te system for thermoelectric material design

Abstract

The Cu-Sb-Te system has attracted keen interest because of the existence of Cu₂Te, Cu₄Te₃, Sb₂Te₃, etc., which show extraordinary properties in thermoelectricity. This work establishes the first complete experimental liquidus projection of the Cu-Sb-Te system based on the microstructural and compositional analysis of a series of key as-cast alloys. Key findings include: 12 primary solidification fields: (Cu), (Sb), (Te), Sb₂Te₃, CuTe, Cu₄Te₃, ζ/ε-Cu₂Te, γ-(Sb, Te), δ-(Sb, Te), β-Cu₃Sb, η-Cu₂Sb and ternary τ-Cu₂Sb_xTe_1−x; a Cu-rich liquid immiscibility dome; 13 invariant reactions including 3 eutectic reactions (E type), 8 transition reactions (U type), 1 peritectic reaction (P type), and a dual-liquid invariant reaction. The projection provides a diagram foundation for designing Cu-Te thermoelectrics.

Keywords

liquidus projection / Cu-Sb-Te system / phase diagram / experimental investigation / egg-shaped microstructure / liquid immiscibility dome

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