Superconductivity and magnetism in MPt4Ge12, M = Ca, Ba, Sr, Eu

X-ray powder data for Ba0.8Ca0.2Pt4Ge12 and X-ray single crystal data for EuPt4Ge12 define cubic body-centered symmetry consistent with novel Ge-based skutterudites SrPt4Ge12 and BaPt4Ge12 (space group Im (3) over bar). Structural and electron microprobe analysis investigations evidence a complete filling of the icosahedral cages without large atomic displacement parameters. Ba0.8Ca0.2Pt4Ge12 exhibits phonon-mediated superconductivity at T-c = 5.2 K. Density functional theory (DFT) calculations (LDA+U) carried out for EuPt4Ge12 proved that Eu guest atoms strongly stabilize the compound in which the calculated density of states around the Fermi energy essentially consists of hybridized Ge 4p-like and Pt 5d-like states. Low temperature resistivity studies evidence magnetic ordering at T-m approximate to 1.7 K. Susceptibility measurements reveal a divalent state for europium, in excellent agreement with the DFT calculations.