Synthesis, crystal structure, electrical and thermal transport properties of the skutterudite derivative RhGe1.5-xSe1.5+x

The skutterudite-derivative phase RhGe1.5-xSe1.5+x has been synthesized and structurally characterized by metallography and powder X-ray diffraction. At x = 0, RhGe1.5Se1.5 displays trigonal symmetry, space group R (3) over bar, with unit cell parameters a = 12.0601(8) angstrom, c = 14.826(1) angstrom, V = 1867.5(4) angstrom(3), and Z = 24. The crystal structure can be viewed as a modification of the cubic structure of the skutterudite CoAs3, where Ge and Se anions order in layers perpendicular to the [111] direction of the cubic skutterudite unit cell. Electrical resistivity, See-beck coefficient and thermal conductivity of the phase RhGe1.5-xSe1.5+x (P-type semiconductor) have been investigated for different x values in the temperature range from 3 to 640 K.