Nanostructured copper-selenide with high thermoelectric figure-of-merit and process for the preparation thereof

Patent metadata

Field	Value
Publication number	US-9865791-B2
Application number	US-201415021661-A
Country	US
Kind code	B2
Filing date	Mar 12, 2014
Priority date	Sep 12, 2013
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

Disclosed is a nanostructured p-type copper-selenide as a cost-effective thermoelectric material with a high thermoelectric figure-of-merit. The nanostructured copper-selenide is a cost-effective p-type thermoelectric material having a high figure-of-merit of 2 at 973 K and is synthesized employing high energy ball milling process followed by reaction sintering under pressure at high heating rates using spark plasma sintering of the resulting nanopowders. The sintered copper-selenide shows a density of 99.9% of theoretical density and retains the nanoscale features introduced during ball milling leading to a thermoelectric figure of merit of 2 at 973 K.

First claim

We claim:

1. A nanostructured copper-selenide having a formula of Cu X Se X-1 , wherein X has an atomic ratio in the range of 1.99 to 2.01, and wherein the copper-selenide is a p-type thermoelectric material with a high thermoelectric figure-of-merit of 2 at 973K.

2. The nanostructured copper-selenide of claim 1 , wherein the nanostructured copper-selenide has an average crystallite size in the range of 5 nm to 30 nm.

3. A process for the synthesis of the nanostructured copper-selenide of claim 1 comprising the steps of:
i. mixing copper (Cu) and selenium (Se) powders in an atomic ratio ranging between 1.97 to 2.03 to obtain a mixture;
ii. milling the mixture as obtained in step (i) by using balls in a high energy ball mill with a 2 to 4 weight percent process control reagent at a speed of 300 to 400 rpm for a period in the range of 40 to 70 hours to obtain a Cu and Se nanopowder;
iii. compacting the Cu and Se nanopowder as obtained in step (ii) on a hydraulic press at a pressure of 0.3 to 0.5 MPa to obtain a compacted pellet;
iv. consolidating the compacted pellet as obtained in step (iii) using a spark plasma sintering process in a vacuum for a period in the range of 3 to 5 minutes followed by cooling and releasing the pressure to obtain nanostructured copper-selenide.

4. The process of claim 3 , wherein a ball to powder weight ratio in the range of 15:1 to 20:1 is used in the high energy ball mill of step (ii).

5. The process of claim 3 , wherein the Cu and Se nanopowder is compacted in a 12.7 mm inner diameter high strength graphite die.

6. The process of claim 3 , wherein the 2 to 4 weight percent process control reagent is stearic acid.

7. The process of claim 3 , wherein the spark plasma sintering process is carried out at a pressure of 50 to 80 MPa.

8. The process of claim 3 , wherein the spark plasma sintering process is carried out at a temperature in the range of 800 to 900 K with a heating rate of 300 to 450 K/min in a vacuum of 3 to 8 Pa in a high-strength graphite die.

9. The process of claim 3 , wherein the milling is carried out in an inert atmosphere of argon gas.

Assignees

• Council Scient Ind Res

Inventors

• Gahtori Bhasker
• Bathula Sivaiah
• Tyagi Kriti
• Srivastava Avanish Kumar
• Dhar Ajay
• Budhani Ramesh Chandra

Classifications

• C01B19/007 Primary

  Tellurides or selenides of metals (C01B19/002 takes precedence) · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• H01L35/26

  Electricity · mapped topic

• C01P2002/74

  by peak-intensities or a ratio thereof only · CPC title

• H01L35/16 Primary

  Electricity · mapped topic