Effect of the Calcination Conditions on Composition and Properties of Mn-Zn Ferrites Prepared by Sol-Gel Method

A series of Mn-Zn ferrite particles were prepared by a template-assisted sol-gel method and calcined at 773, 973 and 1173 K in air, nitrogen and nitrogen after precalcination at 573 K for 1 h in air. The effects of calcination conditions on composition, morphology and properties of Mn-Zn ferrites were investigated by XRD, TEM, VSM and impedance analyzer. It is found that Mn-Zn ferrites with pure spinel structure, uniform size and morphology are obtained only in nitrogen after precalcination at 573 K for 1 h in air, which provide a new way to prepare Mn-Zn ferrite nanoparticles with spinel structure. The reaction mechanisms of the Mn-Zn ferrites in different calcination atmospheres were analyzed. The calcining temperature has a major influence on the morphology and properties of the Mn-Zn ferrite particles with spinel structure obtained; and with the increasing of the calcination temperature, the particles become larger in size, M-s increases monotonically, H-c first increases and then decreases, T-c decreases monotonically. The permittivity first increases and then decreases, and the dielectric loss shows a sharp rise after slightly decreasing trend with the increasing of frequency.