Structural Phase Transitions in a New Compound Eu2AgGe3

A new intermetallic compound Eu2AgGe3 has been synthesized using high-frequency induction heating method. Single-crystal X-ray diffraction data showed that Eu2AgGe3 crystallizes in the orthorhombic Ba2LiSi3 structure type, with Fddd space group and lattice parameters a = 8.7069(17) Å, b = 15.011(3) Å, c = 17.761(4) Å. Eu2AgGe3 is composed of infinite arrays of hexagonal [Ag3Ge3] units stacked along the [001] direction, and the Eu sites are sandwiched between these parallel hexagonal networks. Temperature-dependent powder XRD data and DTA hint toward a structural phase transition from orthorhombic to hexagonal above 477 K and an unusual reversible transition to the original phase, i.e., orthorhombic phase at around 718 K. Magnetic measurements on Eu2AgGe3 sample show paramagnetic behavior above 100 K and weak ferromagnetic interactions below 80 K. Mössbauer spectroscopy and X-ray absorption near-edge spectroscopic (XANES) studies reveal that Eu atoms in Eu2AgGe3 exist in the divalent oxidation state.