LAUSR

Zn- and Al-substituted cobalt ferrite ZnxCo1−xFe2−xAlxO4 (0 ≤x≤$\leq x \leq $ 0.9) with particle size in the range of 6–13 nm were synthesized by glycol-thermal reaction. The compounds were investigated by electron spin resonance (ESR) measurements. CoFe2O4 (x = 0) shows a broad ESR signal associated with magnetic dipole-dipole interactions among particles which is highly sensitive to the Zn and Al ion concentrations. Narrower ESR signals in Zn- and Al-doped samples are attributed to the weakening of super-exchange interactions. ESR and magnetization measurements reveal a reduction in magnetization with increasing particle size. This is explained on the basis of the redistribution of Zn2+ ions in both tetrahedral (A) and octahedral (B) sites in fine powders.