Cation distribution and magnetisation study of $Nd^{+3}$ substituted Zn-Mg ferrites

Özet

Polycrystalline ferrites $Zn_xMg_{1-x}Fe_{2-y}Nd_y O_4$ (x = 0.00, 0.20, 0.40, 0.80 and 1.00; y = 0.00, 0.05 and 0.10) were prepared by standard ceramic method.The compositions,on characterisation by X-ray diffraction, shows formation of single phase cubic spinels. Magnetic measurement of these composition shows increase in magnetic moment $n_{\beta}$ with $Zn^{2+}$ concentration up to x = 0.4 and decreases thereafter. This is attributed to the existence of locallised canted spin. The compositions for x = 0.8 and 1.0 shows paramagnetic behaviour at and above room temperature. The trivalent substitution of $Nd^{3+}$ ion causes reduction in the magnetic moment. The cation distribution of the sytem was investigated by comparing observed and calculated Curie temperatures, employing a modified Upadhyay model, wherein relative weighted magnetic interaction per formula unit is considered. From this it is found that the Zinch shows strong occupancy on tetrahedral sites, whereas magnesium ion preferentially distributes among A and B sites, showing maximum occupancy on A sites for x = 0.20. The substitution of $Nd^{3+}$ ion causes an increase in the occupancy of magnesium ion on A sites.