Crystal structure and thermoelectric properties of novel skutterudites Ep/sub y/Ni/sub 4/Sb/sub 12-x/Sn/sub x/ with Ep=Sn, Eu and Yb

A novel ternary phase, Sn/sub y/Ni/sub 4/Sb/sub 12-x/Sn/sub x/ has been characterised exhibiting a wide range of homogeneity (at 250/spl deg/C. 2.4/spl les/x/spl les/5.6; 0/spl les/y/spl les/0.31). Sn/sub y/Ni/sub 4/Sb/sub 12-x/Sn/sub x/ crystallises in a skutterudite based structure in which Sn atoms are found to occupy both the 24 g site randomly sharing with Sb atoms and the 2a position, with an anomalously large isotropic atomic displacement parameter. Eu/sub 0.8/Ni/sub 4/Sb/sub 5.8/Sn/sub 6.2/, Yb/sub 0.6/Ni/sub 4/Sb/sub 6.7/Sn/sub 5.3/ and Ni/sub 4/As/sub 9.1/Ge/sub 2.9/ are isotypic skutterudites. Depending on the particular composition, metallic as well as semiconducting behaviour was observed. Eu containing compounds exhibit long range magnetic order arising from the Eu/sup 2+/ ground state.