Europium spin dilution in the ferromagnetic solid solution Eu_4–x Ca _x PdMg

Abstract

The intermetallic compounds Eu4PdMg and Ca4PdMg form a complete solid solution Eu4–x Ca x PdMg. Further phase analytical studies showed that Eu4PdMg does not allow substitution with strontium. The polycrystalline Eu4–x Ca x PdMg samples were characterized by powder X-ray diffraction. The structure of Eu2.233(6)Ca1.767PdMg was refined from single crystal X-ray diffractometer data: Gd4RhIn type, F 4 ‾ 3m, a = 1,475.42(10) pm, wR2 = 0.0476, 674 F 2 values, 23 variables. Temperature dependent magnetic susceptibility measurements show a drastic decrease of the Curie temperature with increasing calcium substitution. 151Eu Mössbauer spectra of Eu4PdMg and Eu2Ca2PdMg confirm the divalent ground state of europium.