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

Abstract

The indium‐rich intermetallic compound Eu3Rh2In15 was synthesized from the elements in a sealed tantalum ampoule at high temperature. Small silvery single crystals were obtained by slow cooling of the sample. Eu3Rh2In15 was studied by X‐ray diffraction on powders and single crystals. Its tetragonal Eu3Co2In15 type structure was refined from single crystal diffractometer data: P4/mbm, a = 1483.46(7), c = 439.70(3) pm, wR2 = 0.0205, 1092 F2 values and 38 parameters. The In1, In2 and In4 atoms in the Eu3Rh2In15 structure build up planar layers that are a tessellation of triangles, squares and pentagons. These layers are stacked in an AA sequence. The Rh atoms fill the trigonal prisms, Eu2, In3, and In5 square prisms and the Eu1 atoms the pentagonal prisms. The high indium content in Eu3Rh2In15 leads to a broad range of In–In distances (310–370 pm) and substantial In–In bonding within the three‐dimensional indium substructure. Temperature dependent magnetic susceptibility measurements show Curie–Weiss behavior and the experimental magnetic moment of 8.0(1) μB Eu atom–1 is compatible with divalent europium. Magnetization and specific heat data point to long‐range magnetic ordering at 14.0(2) K with a canted spin arrangement. 151Eu Mössbauer spectra confirm the divalent character of europium and underline the complex magnetic ordering. The two crystallographically independent europium sites show different isomer shifts [–11.06(2) mm·s–1 for Eu1 and –9.09(5) mm·s–1 for Eu2] and different magnetic hyperfine fields [16.1(1) T for Eu1 and 32.6(1) T for Eu2].