Magnetic properties and microstructure of Zr4+ substituted Mg-Zn ferrites

Magnetic moment and saturation magnetization of ZnxMg1-x+yZryFe2-2yO4 (x = 0.1, 0.2, 0.3, 0.4, 0.5 and y = 0.01, 0.03, 0.05, 0.07) ferrites obey the N eel's two sublattice model for x less than or equal to 0.3 and for x > 0.3 the Y-K model holds good. The Y-K angle is found to increase with Zn concen tration above x = 0.3. The small values of M-r/M-s and the variation of AC susceptibility with temperature indicate the presence of multidomain (MD) p articles in thr samples. The Curie temperatures obtained from AC susceptibi lity measurements are in good agreement with those obtained from the Loroia technique. A sudden drop of the chi(ac) versus T curve near the Curie temp erature confirms the formation of a single phase material. The SEM microgra phs reveal that the average grain size increases with Zr up to y = 0.05 and then decreases for y > 0.05. A similar trend is observed in the variation of 4 pi M-s with Zr content. (C) 1999 Elsevier Science S.A. All rights rese rved.