MAGNETIC-PROPERTIES OF DILUTED MAGNETIC (GD,LU)(2)O-3

The magnetic susceptibility of the diluted magnetic Lu2-xGdxO3 (x=0.06 , 0.10, 0.22, 0.40, 1.00, 1.40; 1.80) was measured in the temperature range 1.7-295 K. The inverse susceptibility changes slope to a smaller value below 2.2 K for the samples with x less than or equal to 0.40. In the cubic Lu0.20Gd1.80O3 the slope increases below 2.8 K. These cha nges are attributed to the large difference in susceptibility for two cationic sites at low temperatures and to the crystallographic distrib ution of Gd3+ ions. The monoclinic Lu0.20Gd1.80O3, which was obtained from the stoichiometrically similar cubic phase at 1620 K, has an anti ferromagnetic phase transition at 3.4 K. The magnetic-ion distribution for low-concentration samples (x = 0.06, 0.10) was studied using an i solated-cluster method in the nearest-neighbor approximation. In these samples a tendency for magnetic-ion cluster formation was found. A ra ndom cluster distribution was found to be consistent with the suscepti bility data for the sample with x = 0.06. For the x = 0.10 sample the susceptibility calculated with a modified cluster distribution gives t he best agreement with the experimental results.