EuIrIn₄ with LaCoAl₄ Type Structure – Synthesis, Magnetic Properties, and ¹⁵¹Eu Mössbauer Spectroscopy

Abstract

LaCoAl4 type EuIrIn4 was synthesized by induction‐melting of the elements in a sealed tantalum ampoule, followed by annealing of the sample in a high‐frequency or in a muffle furnace. The EuIrIn4 structure was refined from single‐crystal X‐ray diffraction data: Pmma, a = 860.65(3), b = 430.33(6), c = 757.65(7) pm, wR = 0.0748, 633 F2 values and 24 variables. The striking building units are iridium‐centered trigonal prisms of indium atoms, distorted bcc indium cubes and a pentagonal prismatic indium coordination of the europium atoms. Within the three‐dimensional [IrIn4]2– polyanionic network the Ir–In and In–In distances range from 260–288 pm and 306–332 pm, respectively. The divalent ground state of europium was manifested through magnetic [7.96(1) μB / Eu atom, TN = 7.9(1) K] and 151Eu Mössbauer spectroscopic data [δ = –10.54(2) mm·s–1; Bhf = 19.1(1) T at 6 K].

Structure, Magnetic Properties, and 151Eu Mössbauer Spectra of the Indium‐rich Phase Eu3Rh2In15

“…[32] This motif is observed in most indium-rich intermetallic phases and examples of such distorted cubes are summarized in the literature. [38,41,42] Nevertheless, we need to keep in mind that the In@In 8 cubes adjust to the other polyhedra in the ternary structures and we therefore observe different c/a ratios for the unit in the ternaries. In elemental indium, the fcc arrangement is slightly distorted (c/a = 1.52 instead of √2≈1.4142) and this distortion is associated with antibonding s-s states that are raised above the Fermi level, thus stabilizing the indium structure.…”