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

Abstract

The new phases Ca₃Pt_4+xGe_13−y (x = 0.1; y = 0.4; space group I2₁3; a = 18.0578(1) Å; R_I = 0.063; R_P = 0.083) and Yb₃Pt₄Ge₁₃ (space group P4₂cm; a = 12.7479(1) Å; c = 9.0009(1) Å; 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 4f¹⁴ (Yb²⁺) configuration validated by X-ray absorption spectra and resonant inelastic X-ray scattering data. Ca₃Pt_4+xGe_13−y is diamagnetic (χ₀ = −5.05 × 10⁻⁶ emu mol⁻¹). The Sommerfeld coefficient γ = 4.4 mJ mol⁻¹ K⁻² for Ca₃Pt_4+xGe_13−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 (θ_D) is 398 K.