EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Over the last decades, the negative consequences of climate change and the exhaustion of fossil fuels have brought to the forefront one major challenge: the energy crisis. Thermoelectric materials can significantly contribute to the solution of this problem because of their capability to convert heat into electricity and vice versa. Half-Heusler (HH) compounds were recently identified as promising thermoelectric materials for medium-high temperature range applications. Reasonably high ZTs of up to ~1, were achieved for both n- and p- type compositions which were mainly prepared by arc-melting method followed by several days of annealing. Even though the results are encouraging, the high cost of Hf and the time consuming annealing process remain barriers for the applicability of HH alloys in thermoelectric devices.
The aim of this work is to achieve a high thermoelectric performance in (Hf,Zr, Ti)Co(Sb,Sn) solid solutions with reduced Hf concentration, prepared by mechanical-alloying as an advantageous method. The temperature dependent thermoelectric properties (electrical conductivity, thermal conductivity and Seebeck coefficient) were measured on hot pressed pellets and the thermoelectric power factor and dimensionless figure of merit (ZT) values were estimated. In this presentation, our recent results on different compositions of (Hf,Zr,Ti)Co(Sb,Sn) based materials that were successfully prepared by mechanical alloying will be discussed.