Structure and low-temperature properties of Ba8Ni6Ge40

Structural, magnetic, heat capacity, electrical and thermal transport properties are reported on polycrystalline Ba8Ni6Ge40. Ba8Ni6Ge40 crystallizes in a cubic type I clathrate structure with unit cell a=10.5179 (4) Å. It is diamagnetic with susceptibility χdia=−1.71×10-6 emu/g Oe. An Einstein temperature 75 K and a Debye temperature 307 K are estimated from heat capacity data. It exhibits n-type conducting behavior below 300 K. It shows high Seebeck coefficients (−111×10-6 V/K), low thermal conductivity (2.25 W/K m), and low electrical resistivity (8.8 mΩ cm) at 300 K.