Grain Growth and Magnetic Properties of Nb2O5-Doped NiZn Ferrites

Abstract

The grain growth and magnetic properties of Nb2O5 doped NiZn ferrites prepared by a solid-state reaction method have been investigated. X-ray diffraction (XRD) patterns indicated that a single phase spinel structure was observed when the content of Nb2O5 was less than 1.00 wt %. While 1.00 wt % of Nb2O5 added, besides the spinel phase, an orthorhombic phase of FeNb2O6 appeared which resulted in the (440) diffraction peak to be enhanced as the main peak. In addition, as the content of Nb2O5 increased, the diffraction intensities of the samples increased gradually. The microstructure observation revealed that Nb2O5 addition remarkably retarded grain growth when it below 0.85 wt %. And the addition of 0.85 wt % Nb2O5 induced the formation of a microstructure composed of giant grains with trapped pores embedded in a normal microstructure. Up to a content of 1.00 wt %, grain growth was obviously enhanced. The initial permeability (µi) initially increased up to a content of 0.40 wt % and showed a decrease at higher content up to 1.00 wt %. However, losses (PL) changed contrarily. Saturation induction (Bs) decreased monotonously with increasing Nb2O5 content.