Neutron diffraction studies of the diluted spinel ferrite ZnxMg0.75-xCu0.25Fe2O4

Neutron diffraction studies have been performed in the temperature range 1050 K greater than or equal to T greater than or equal to 10 K on the spinel system ZnxMg0.75-xCu0.25Fe2O4 (x = 0.0, 0.25, 0.5 and 0.75) prepared in the ceramic sintering method. Cation distributions in all the four compositions have been determined from the analysis of neutron data. A perturbed ferrimagnetic order has been observed in the compositions with x values lying in the low to intermediate range, where apparently, randomly canted spins and small fluctuating clusters are superimposed on the ferrimagnetic long range order. A complete breakdown of the ferrimagnetic stability occurs at x = 0.75 as indicated by the absence of magnetic long range order. A huge diffuse scattering signal appears at the low-Q region broadening the (1 1 1) diffraction line in the low temperature neutron patterns of this composition indicating the formation of large magnetic clusters. A cluster spin glass state is suggestive for this composition. (C) 2001 Elsevier Science B.V. All rights reserved.