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 I213; a = 18.0578(1) A; RI = 0.063; RP = 0.083) and Yb3Pt4Ge13 (space group P42cm; a = 12.7479(1) A; c = 9.0009(1) A; RI = 0.061, RP = 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 4f14 (Yb2+) configuration validated by X-ray absorption spectra and resonant inelastic X-ray scattering data. Ca3Pt4+xGe13−y is diamagnetic (χ0 = −5.05 × 10−6 emu mol−1). The Sommerfeld coefficient γ = 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(EF) = 3.3 eV−1/f.u.)); the Debye temperature (θD) is 398 K.