Ca3Pt4+xGe13-y and Yb3Pt4Ge13: new derivatives of the Pr3Rh4Sn13 structure type

The new phases Ca3Pt4+xGe13-y (x = 0.1; y = 0.4; space group I2(1)3; a = 18.0578(1) angstrom; R-I = 0.063; R-P = 0.083) and Yb3Pt4Ge13 (space group P4(2)cm; a = 12.7479(1) angstrom; c = 9.0009(1) angstrom; R-I = 0.061, R-P = 0.117) are obtained by high-pressure, high-temperature synthesis and crystallize in new distortion variants of the Pr3Rh4Sn13 type. Yb3Pt4Ge13 features Yb in a temperature-independent non-magnetic 4f(14) (Yb2+) configuration validated by X-ray absorption spectra and resonant inelastic X-ray scattering data. Ca3Pt4+xGe13-y is diamagnetic (chi(0) = -5.05 x 10(-6) emu mol(-1)). The Sommerfeld coefficient gamma = 4.4 mJ mol(-1) K-2 for Ca3Pt4+xGe13-y, indicates metallic properties with a low density of states at the Fermi level in good agreement with electronic structure calculation (N(E-F) = 3.3 eV(-1)/f.u.)); the Debye temperature (theta(D)) is 398 K.