Development of Copper Selenide Thermoelectric Compound through High Energy Ball Milling and Spark Plasma Sintering Process

Abstract

Many developed and developing countries are taking an intensive effort in identifying the solution to control the greenhouse effect caused by usage of fossil fuels for power generation. In this journey renewable source of energies like solar, wind, tidal and so on are lending their massive support with 0% consumption of fossil fuels. However, in certain circumstances it is necessary to use the fossil fuels. But, nearly 40 50 % of heat energy is exhausted as a waste heat into the environment. Few examples to affirm the above statements are automobiles, electric power generation in power plants, etc. In order to utilize these waste heat into electrical energy, scientific personalities designed a material termed thermoelectric device or thermoelectric power generator . It can directly convert the heat energy into electrical energy. The conversion efficiency of the device is purely depending upon the materials which termed as thermoelectric materials. The thermoelectric materials are semiconductors. newlineCopper selenide (Cu2Se) is considered as a superionic semiconducting thermoelectric material. Research on this material is quite interesting due to its inherent low thermal conductivity and high ZT in the superionic phase. But, synthesis of Cu2Se compound is a challenging task since difficult in maintaining stoichiometry due to selenium loss and time-consuming fabrication process. In this work, first, mechanical alloying technique was used to synthesis the copper selenide compound. The elemental Cu and Se powders were taken to the stoichiometric ratio in tungsten vial for mechanical milling. The BPR and milling speed were fixed as 15:1 and 300 rpm, respectively. The milling process was carried out at different durations like 1h, 5h, 10h and 20h. The XRD analysis of 1h, 5h, 10h and 20h mechanically milled powders are identified as Cu + Se, CuSe + Cu + Se, Cu3Se2 + Cu and and#946; - Cu2Se phases, respectively. DTA studies also report the phase formation of and#945; - Cu2Se from the elemental powder and intermediate phases.