Crystal, electronic structure and physical properties of U3Rh4Ge13 and Th2Rh3Ge5

Abstract

Crystal structures of U3Rh4Ge13 [structure type HT-Y3Pt4Ge13, space group R3c, a = 5.6004(6) Å, c = 15.5158(1) Å, RB = 0.022, Rp = 0.021] and of Th2Rh3Ge5 [structure type U2Co3Si5, space group Ibam, a = 10.0572(1) Å, b = 11.9142(1) Å, c = 6.0997(1) Å, RB = 0.027, RP = 0.037] are refined by powder X-ray diffraction method. Their structural relationships with primitive cubic Yb3Rh4Sn13 and body-centered tetragonal ThCr2Si2 types, respectively are discussed. The ac and dc magnetic susceptibility measurements on U3Rh4Ge13 revealed an antiferromagnetic ordering at TN = 22 K followed by a metamagnetic transition below 5 K. The magnetic entropy Smag ≈ Rln4 at TN indicates U3Rh4Ge13 to follow the classical LS coupling scheme. This finding together with the performed theoretical DFT calculations hint toward localized nature of 5f states in the studied germanide. U3Rh4Ge13 reveals metallic transport properties, low thermal conductivity (i.e. 0.4–0.6 W m−1 K−1) as well as displays a structural phase transition in the temperature range of 292–315 K. Electrical resistivity measurements and theoretical DFT calculations indicated Th2Rh3Ge5 to be a simple metal.