MAGNETIC-PROPERTIES AND FE-57 MOSSBAUER-EFFECT IN UFE10-XNIXSI2 ALLOYS

The magnetic properties and Fe-57 Mossbauer effect in the UFe10-xNixSi 2 system were investigated over a broad temperature range. Magnetic me asurements revealed a ferromagnetic character, with two anomalies in t he temperature dependence of the susceptibility for x > 6 but only one anomaly for x < 6. The temperature of the last anomaly increases as x decreases. The high-temperature anomaly seems to be related to the pr ecipitation of free nickel. The field dependence of the magnetization exhibits remanence for x greater-than-or-equal-to 4. The Fe-57 Mossbau er effect demonstrates that only iron contributes to the magnetic orde ring observed at lower temperatures. It is shown that the substitution of Ni for Fe results in a strong preferential occupation by Ni of the 8(f) site. The decrease in the Curie point and the saturation magneti zation is attributed to the decrease in the number of the nearest neig hbour Fe atoms.