MOSSBAUER-EFFECT AND MAGNETIC-PROPERTIES IN EUMG5 AND EU2MG17

Measurements of the 151Eu Mössbauer effect in EuMg5 and Eu2Mg17 are reported and compared with data obtained previously in EuMg2. The decreasing isomer shift in the sequence Eu metal, EuMg2, EuMg5, Eu2Mg17 is interpreted in terms of increasing charge transfer from Eu to Mg. Magnetic measurements were made in the range 4.2-300 K. In both EuMg5 and Eu2Mg17 Curie-Weiss behaviour is observed down to about 20 K, the effective moment corresponding to Eu in the divalent state. The magnetic ordering temperatures (7.8 K and 7.9 K, respectively) were derived from the temperature dependence of the Mössbauer spectra. Magnetic ordering is probably of the antiferromagnetic type. In Eu2Mg17 magnetic ordering at one of the two Eu sites occurs at a temperature much lower than the ordering temperature corresponding to the other Eu site. The lattice constants for both compounds were determined. © 1979.