Mechanism of Rare Earth Incorporation and Crystal Growth of Rare Earth Containing Type-I Clathrates

Andrey Prokofiev; Robert Svagera; Monika Waas; Matthias Weil; Johannes Bernardi; Silke Paschen

doi:10.1021/acs.cgd.5b00461

Mechanism of Rare Earth Incorporation and Crystal Growth of Rare Earth Containing Type-I Clathrates

Cryst Growth Des. 2016 Jan 6;16(1):25-33. doi: 10.1021/acs.cgd.5b00461. Epub 2015 Dec 2.

Authors

Andrey Prokofiev¹, Robert Svagera¹, Monika Waas¹, Matthias Weil², Johannes Bernardi³, Silke Paschen¹

Affiliations

¹ Institute of Solid State Physics, Vienna University of Technology , Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
² Institute of Chemical Technologies and Analytics, Vienna University of Technology , Getreidemarkt 9/164-SC, 1060 Vienna, Austria.
³ USTEM, Wiedner Hauptstrasse 8-10, Vienna 1040 Austria.

Abstract

Type-I clathrates possess extremely low thermal conductivities, a property that makes them promising materials for thermoelectric applications. The incorporation of cerium into one such clathrate has recently been shown to lead to a drastic enhancement of the thermopower, another property determining the thermoelectric efficiency. Here we explore the mechanism of the incorporation of rare earth elements into type-I clathrates. Our investigation of the crystal growth and the composition of the phase Ba_8-x RE _x TM _y Si_46-y (RE = rare earth element; TM = Au, Pd, Pt) reveals that the RE content x is mainly governed by two factors, the free cage space and the electron balance.