Crystal Structure, Magnetic Properties and Bonding Analysis of M3Pt23Ge11 (M=Ca, Sr, Ba and Eu)

The properties of Pt-based materials can be intriguing due to the importance of spin-orbit coupling for Pt. Herein, we report four new phases with formulas M3Pt23Ge11 (M = Ca, Sr, Ba and Eu), which adopt the same structure type as Ce3Pt23Si11. Magnetic susceptibility measurements indicate that none of the phases is superconducting above 1.8 K, while for Eu3Pt23Ge11 ferromagnetic ordering is observed at ~ 3 K. The low Curie temperature for that material compared to that of Eu3Pt23Si11 may be due to its larger Eu-Eu distance. One potential factor that destabilizes the structure of other rare-earth based M3Pt23Ge11 is demonstrated through COHP calculations.