engleski

Thermoelectric properties of Ba8Au5.25Ge40.3□0.45 under hydrostatic pressure

Due to their relatively large figure of merit, as well as chemical and thermal stability at high temperatures, clathrates are very promising thermoelectric materials. Among clathrate type-I systems, Ba8GaxGe46-x was reported to have the highest ZT value reaching 1.35 for n-type (x=16) and 1.1 for p-type (x=18) crystals. Thus Ba-containing clathrates are considered to be prospective thermoelectrics. In the current spot of interest are ternary type-I clathrates in Ba-Au-Ge and Ba-Ag-Ge systems. The main research activity was focused mainly on solubility of Au, phase equilibria and some transport properties.[1-4] It seems that depending on Au (Ag) content dominant electrical carriers can be of p or n type, while the temperature dependence reveals either metallic or semiconducting behaviour. Hydrostatic pressure is a powerful tool for probing electronic structure of material. Through changing interatomic distances it directly influences band structure increasing overlapping integrals and electronic velocities.

clathrates; transport properties

This work was done within the activities of the European Integrated Center for the Development of New Metallic Alloys and Compounds - C-MAC.