High-temperature transport properties of complex antimonides with anti-Th3P4 structure

Abstract

Polycrystalline samples of R4Sb3 (R = La, Ce, Smand Yb) and Yb4-xR¢xSb3 (R¢ = Sm and La) have been quantitatively synthesized by high-temperature reaction. They crystallize in the anti-Th3P4 structure type (I ¯43d, no. 220). Structural and chemical characterizations have been performed by X-ray diffraction and electron microscopy with energy dispersive X-ray analysis. Powders have been densified by spark plasma sintering (SPS) at 1300 ◦C under 50 MPa of pressure. Transport property measurements show that these compounds are n-type with low Seebeck coefficient except for Yb4Sb3 that shows a typical metallic behavior with hole conduction. By partially substituting Yb by a trivalent rare earth we successfully improved the thermoelectric figure of merit of Yb4-xR¢xSb3 up to 0.75 at 1000 ◦C.