Consideration on theapplicability of the intermetallic compounds with a large coordination numberas thermoelectric materials on the basis of the calculated electronic densitiesof states

Y. Imai¹, A. Watanabe¹, Y.Amagai², A. Yamamoto³

¹National Institute of AdvancedIndustrial Science and Technology, AIST Tsukuba Central 5, Higashi 1-1 Tsukuba,Ibaraki 305-8565, Japan

²Tokyo University of Science, 2641Yamazaki, Noda, Chiba 278-8510, Japan

³National Institute of AdvancedIndustrial Science and Technology, AIST Tsukuba Central 2, Umezono 1-1 Tsukuba,Ibaraki 305-8568, Japan

An atom mustvibrate so as for a phonon to propagate through a lattice but the moreneighbors a particular atom is coordinated to, the less free it is to vibrate.So, compounds with larger coordination number sites are known to be likely tohave low lattice thermal conductivity. However, materials belonging to thiscategory have not been the target of the previous explorations of thethermoelectric materials (TEM) with high thermoelectric performance. Since theatoms of the following types of structure have large coordination numbers from16 to 24, they can be the candidates of TEM with low lattice heat conduction;NaZn13-, BaCd11-, MnTh12-, Ni17Th2-,Zn17Th2-, and CaCu5- typestructures.

In thepresent study, the applicability of the intermetallic compounds with the abovetypes of structure as TEM will be discussed on the basis of the calculatedelectronic densities of states.