Diluting europium spins – a magnetic and 151Eu Mössbauer spectroscopic investigation of the solid solution Eu1−xSrxPtIn2

Abstract

The indide EuPtIn₂ (MgCuAl₂ type, Cmcm, a = 448.23(4), b = 1068.64(11), c = 784.09(8) pm, wR₂ = 0.0432, 466 F² values, 16 variables) was synthesized by induction-melting of the elements and subsequent annealing. The platinum and indium atoms built up a three-dimensional [PtIn₂]²⁻ polyanionic network (278–282 pm Pt–In) which contains channels that are filled with the europium cations. These bind to the network through shorter Eu–Pt contacts (302–323 pm). Temperature dependent magnetic susceptibility and ¹⁵¹Eu Mössbauer spectroscopic data manifest divalent europium down to 4.2 K. EuPtIn₂ orders ferromagnetically at 32.5 K. EuPtIn₂ and SrPtIn₂ form a complete solid solution Eu_1−xSr_xPtIn₂ with Vergard type behavior for the lattice parameters. Divalent europium is proven through magnetic data and Mössbauer spectroscopy. The Curie temperature decreases monotonically from 32.5 to 3.1 K in going to Eu_0.1Sr_0.9PtIn₂.