Preparation method of MgAgSb thermoelectric material

Abstract

The invention discloses a preparation method of a MgAgSb thermoelectric material. The method comprises the following specific steps: (1) proportioned raw material powder is put in a graphite crucible,is placed in a vacuum microwave sintering furnace, is insulated at 950-1000 DEG C for at least 20 min for microwave smelting, and is cooled to obtain an initial ingot; (2) alloy powder obtained by grinding of the ingot is loaded in a mold for hot-press sintering and compact molding to obtain a compact-molded block body at a sintering temperature of 450-500 DEG C; and (3) the block body is treatedby at least 5 days under 543-573 K for microwave sintering and annealing to obtain a single-phase alpha-MgAgSb thermoelectric material. The key overall flow process design of the preparation method is improved; the microwave smelting is combined with the microwave sintering process to prepare the MgAgSb thermoelectric material; and the condition parameters adopted by the microwave smelting and the microwave sintering process are optimized to prepare the alpha-MgAgSb thermoelectric material.

Description

technical field [0001] The invention belongs to the technical field of preparation of thermoelectric materials, and more specifically relates to a preparation method of MgAgSb series thermoelectric materials. Background technique [0002] With the increasingly prominent energy and environmental issues, MgAgSb series thermoelectric materials have gradually attracted widespread attention due to their abundant reserves of constituent elements in the earth's crust, and are regarded as one of the most promising near-room temperature thermoelectric materials. MgAgSb has a complex phase transition, from room temperature to high temperature, there are high-temperature phases of half-heusler structure γ-MgAgSb, Cu 2 The medium-temperature phase β-MgAgSb with Sb structure and α-MgAgSb with tetragonal structure, but only the room-temperature phase α-MgAgSb exhibits good thermoelectric properties. For α-MgAgSb materials, the melting points of Mg and Ag are very different, and the exist...

AI Technical Summary

Problems solved by technology

For α-MgAgSb materials, the melting points of Mg and Ag are very different, and the existing smelting and preparation methods have certain difficulties. In addition, after smelting, a long-term high-temperature heat preservation treatment is required for 14 days to obtain the required α-MgAgSb Material

The preparation of α-MgAgSb thermoelectric materials usually adopts high-temperature melting method and mechanical alloying method (see ① Ying, P., Liu, X., Fu, C., Yue, X., Xie, H., Zhao, X., et al.Chemistry of Materials, 2015, 27(3):909-913; ②Liu, Z., Mao, J., Sui, J., et al, Energy&Environmental Science, 2018.), but these two traditional preparations α -The MgAgSb method and the α-MgAgSb material itself currently have the following main problems: (1) The high-temperature smelting method has a long preparation cycle, high energy consumption, and high cost

(2) During the preparation process of the mechanical alloying method, the powder is easy to stick to the ball or the inside of the ball mill tank, and there are likely to be impurities such as MgAg in the first step of ball milling, which is not conducive to controlling the specific component content of the sample

(3) Under the high-energy conditions of the mechanical alloying method, extremely fine alloy powders are prone to violent chemical reactions, which pose a threat to personal and property safety

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