Crystal structure, and physical properties of the novel compounds EuRh3Ge7 and EuIr3Ge7

Magnetization, heat capacity, thermal expansion and electrical resistivity at various magnetic fields were measured revealing second order phase transitions at 20 K for EuRh3Ge7, and 87 K for EuIr3Ge7, respectively. While this transition is clearly antiferromagnetic in the case of EuRh3Ge7, the nature of this transition remains unclear for EuIr3Ge7. The evaluation of magnetic susceptibility as well as heat capacity data reveals an intermediate valence state of Eu-ions in both compounds.