Cubic-phase silver sulfide-based thermoelectric material and preparation method and application thereof

Abstract

The invention provides a cubic-phase silver sulfide-based thermoelectric material and a preparation method and application thereof, and belongs to the technical field of thermoelectric materials. The chemical formula of the thermoelectric material is Ag < 2-x > S < 0.5 > Se < 0.25 > Te < 0.25 >, wherein 0 lt; xlt; and 0.06 part. According to the invention, on the basis of the existing cubic phase silver sulfide-based thermoelectric material Ag2S0. 5Se0. 25Te0. 25, collaborative optimization of thermal and electrical properties of the material is realized by introducing silver vacancies. The room temperature thermoelectric figure of merit of the optimal sample Ag1, 96S < 0.5 > Se < 0.25 > Te < 0.25 > reaches 0.43 and is improved by 8 times compared with that of Ag2S < 0.5 > Se < 0.25 > Te < 0.25 >. Compared with the prior art, the thermoelectric performance of the obtained thermoelectric material is obviously improved. And elements required for material preparation are rich in reserves and low in price, the preparation process is simple, and large-scale production and commercial application are facilitated.

Claims

1. A cubic silver sulfide-based thermoelectric material, characterized in that: The structural chemical formula of the cubic silver sulfide-based thermoelectric material is Ag 2-x S 0.5 Se 0.25 Te 0.25 , where 0 <x<0.06。 2. The cubic silver sulfide-based thermoelectric material according to claim 1, characterized in that: x＝0、0.02、0.04。 3. The cubic silver sulfide-based thermoelectric material according to claim 1, characterized in that: When x=0.04, the room temperature thermoelectric figure of merit of the cubic silver sulfide-based thermoelectric material is 0.4-0.45, and the power factor is 5.5-6 μW cm -1 K -2 , the total thermal conductivity is 0.3~0.5W m -1 K -1 .

4. A method for preparing a cubic silver sulfide-based thermoelectric material according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: Step 1: Weigh elemental Ag, elemental S, elemental Se, and elemental Te respectively according to the stoichiometric ratio of Ag 2-x S 0.5 Se 0.25 Te 0.25 where 0 < x < 0.06; Step 2: Mix the Ag, S, Se and Te weighed in step 1 and ball mill them to obtain Ag 2- x S 0.5 Se 0.25 Te 0.25 alloy powder; Step 3: The Ag obtained in step 2 2-x S 0.5 Se 0.25 Te 0.25 The alloy powder is sintered under vacuum conditions, pressure is applied and maintained during the sintering process, and the powder is cooled to obtain the cubic silver sulfide-based thermoelectric material.

5. The method for preparing cubic silver sulfide-based thermoelectric material according to claim 4, characterized in that: In step 1, Ag, S, Se, and Te are weighed separately under an inert atmosphere.

6. The method for preparing cubic silver sulfide-based thermoelectric material according to claim 4, characterized in that: In step 2, the mixing and ball milling process is carried out under an inert atmosphere; In step 2, the ball milling specifically includes the following process: adding ball milling beads, sealing the ball milling jar, placing the ball mill in a ball mill for ball milling, and ball milling for 10-20 hours at a rotation speed of 400-500 rpm.

7. The method for preparing cubic silver sulfide-based thermoelectric material according to claim 6, characterized in that: The ball mill is a planetary ball mill, the ball milling jar and ball milling beads are both made of tungsten carbide, the ball milling beads have a diameter of 2-5 mm, and the number is 50-100.

8. The method for preparing cubic silver sulfide-based thermoelectric material according to claim 4, characterized in that: Step 3 specifically includes the following process: Under inert atmosphere, the Ag obtained by ball milling in step 2 was 2-x S 0.5 Se 0.25 Te 0.25 The alloy powder is transferred to a graphite mold, and a graphite punch is placed in the graphite mold. The filled graphite mold is transferred to a sintering cavity, and then vacuumed to 3-5 Pa, a pressure of 40-70 MPa is applied and maintained for 20-30 minutes. After the pressure stabilizes, the temperature is increased to 300-500° C. and maintained for 10-20 minutes. After the sintering is completed, the pressure is released at the same time, and the sample is cooled with the furnace and sintered into a dense block to obtain the cubic phase silver sulfide-based thermoelectric material.

9. The method for preparing cubic silver sulfide-based thermoelectric material according to claim 8, characterized in that: In step 3, the sintering method is spark plasma sintering; In step 3, the heating rate of the temperature is 40 to 60° C. / min.

10. A use of the cubic silver sulfide-based thermoelectric material according to any one of claims 1 to 3, characterized in that: The cubic silver sulfide-based thermoelectric material is used to power flexible electronic devices.

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