Effect of Rh Substitution for Co on the Thermoelectric Properties of CoSb<SUB>3</SUB>

Abstract

CoSb 3 is known as a skutterudite compound that could exhibit high thermoelectric figure of merit. However, the thermal conductivity of CoSb 3 is relatively high. In order to enhance the thermoelectric performance of this compound, we tried to reduce the thermal conductivity of CoSb 3 by substitution of Rh for Co. The polycrystalline samples of (Co 1Àx Rh x )Sb 3 (x ¼ 0, 0.1, 0.2, and 0.3) were prepared and the thermoelectric properties such as the Seebeck coefficient, electrical resistivity, and thermal conductivity were measured in the temperature range from room temperature to 750 K. The Rh substitution for Co reduced the lattice thermal conductivity, due to the alloying scattering effect. The minimum value of the lattice thermal conductivity was 4 Wm À1 K À1 at 750 K obtained for (Co 0:7 Rh 0:3 )Sb 3 .

Effects of Tl-filling into the voids and Rh substitution for Co on the thermoelectric properties of CoSb3

“…7, together with the literature data for CoSb 3 [10,16]. Since Tl-filling and Rh substitution resulted in significant reduction of Ä lat , the enhancement of ZT was achieved.…”

“…Since up to approximately 22% of the voids in CoSb 3 can be filled with Tl [9,10] and the TE properties of (Co 1−y Rh y ) 4 Sb 12 (y = 0.1, 0.2, 0.3) have been studied [16], we determined the composition of the samples prepared in the present study as Tl x (Co 1−y Rh y ) 4 Sb 12 (x = 0, 0.05, 0.10, 0.15, 0.20 and y = 0.1, 0.2). The polycrystalline samples were prepared from stoichiometric amounts of Tl, Rh, Co, and Sb chunks by direct reactions in sealed silica tubes.…”

“…For example, in the systems of Si-Ge alloy [11], (Zr,Hf)NiSn [12], and Ti(Co,Rh)Sb [13] the reduction of the Ä lat through the alloy scattering effect have been achieved. In the CoSb 3 system, the Ä lat reduction has been observed in Co(Sb,As) 3 [14] and (Co,Rh)Sb 3 [15,16].…”

Thermoelectric Properties of CoSb3-based Skutterudite Compounds

“…When the third atom incorporates into the void, the formula of the compounds turns out to be RM 4 X 12 , where R is most often a rare-earth element, called filledskutterudite structure [8]. Here we present the thermoelectric properties of (Co,Rh)Sb 3 and Tl-filled CoSb 3 that have been examined in our group [13,14]. Therefore, the introduction of R atoms into the voids of the skutterudites is an effective method of reducing the lattice thermal conductivity such as thallium-filled skutterudites [9].…”