Structure, Stoichiometry, and Properties of the Chimney-Ladder Phases Ru2Ge3+x (0<x<1)

✍ Scribed by M.A. Hayward; A.P. Ramirez; R.J. Cava

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 271 KB
• Volume: 166
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2002.9611

✦ Synopsis

The preparation and physical characterization of nonstoichiometric Ru 2 Ge 3+x (0rxr1) are reported for the first time. The defect TiSi 2 -type chimney-ladder structure is maintained for the full stoichiometry range. The resistivity of Ru 2 Ge 3+x increases systematically with x from 300 mX cm, x=0 -3 X cm, x=1 at 300 K. The temperature dependence is consistent with a variable range-hopping mechanism for xZ0.6. The Seebeck coefficients of samples do not evolve simply with x. A low thermal conductivity (j 300 K =0.03 W/K cm) suggests that Ru 2 Ge 3 has some of the properties of a phonon-glass-electroncrystal. The low value of the thermoelectric figure of merit ZT=3.2 Â 10 À3 (T=300 K) calculated for Ru 2 Ge 3 is due primarily to a low conductivity.