a kind of ag 2 Non-fired densification preparation process of se bulk thermoelectric materials

Abstract

The invention discloses an unfired densification preparation process of an Ag2Se block thermoelectric material for the first time. According to the unfired densification preparation process, Ag powder and Se powder serve as raw materials and are ground automatically and evenly mixed, then Ag2Se compound powder is obtained, and then the Ag2Se compound powder is put into a WC die; and certain pressure is applied by a pressing machine, and the dense Ag2Se block thermoelectric material can be obtained within minutes. The unfired densification preparation process is simple and extremely short in preparation time, no electricity or heat is consumed in the preparation process, an obtained product is even in component distribution, and Ag+ migration brought by heat treatment can be avoided to a great extent. The prepared Ag2Se block thermoelectric material is excellent in performance, ZTmax is equal to 1.2 @118 DEG C, and a good basis is established for large-scale preparation and large-scale application of Ag2Se compounds.

Description

technical field [0001] The invention belongs to the technical field of thermoelectric material preparation, in particular to an Ag 2 Non-fired densification preparation process of Se bulk thermoelectric materials. Background technique [0002] In the field of material science, transition metal chalcogenides have attracted extensive interest of researchers because of their special photoelectric and chemical properties. Ag 2 Se compound is one of the substances that has been widely concerned by people. Ag 2 Se is a narrow-bandgap semiconductor material that undergoes a reversible phase transition (orthorhombic system-body-centered cubic system) at 406K. Before and after the phase transition, the electrical properties of the compound undergo a sudden change, mainly due to the significant change in the energy band structure. Since the first-order phase transition is instantaneous, the compound Ag 2 Se can be used to fabricate photonic crystals with thermally switchable stop...

AI Technical Summary

Problems solved by technology

However, only Ag was prepared under dynamic loading 2 Se powder, although the static load can be used to prepare blocks, the amount of single preparation is very small

Once bulk thermoelectric materials are prepared in large quantities, uniform Ag2Se bulk materials cannot be obtained under the constraints of existing jack tablet presses and steel molds, and Ag and Se raw materials will be incompletely reacted and remain

They undergo subsequent reactions in the obtained block, releasing heat to cause local stress concentration, leading to block cracking, and the densification of the product cannot be achieved, which limits the use of thermoelectric materials. In addition, the compound Ag in the high temperature phase 2 Se is a fast ion conductor, for Ag 2 Se compounds, when higher than 406K, Se atoms form a body-centered cubic structure, Ag + can freely migrate in the gaps of the Se atomic framework

Current high-temperature densification technologies, such as hot pressing, spark plasma sintering (SPS) and plasma activation sintering (PAS), are unavoidable temperature gradients caused by uneven temperature fields, resulting in Ag + inhomogeneous composition

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