Grain Growth And Magnetic Properties Of Nb_2o_5-doped Nizn Ferrites

摘要

The grain growth and magnetic properties of Nb_2O_5 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 Nb_2O_5 was less than 1.00 wt%. While 1.00 wt% of Nb_2O_5 added, besides the spinel phase, an orthorhombic phase of FeNb_2O_6 appeared which resulted in the (440) diffraction peak to be enhanced as the main peak. In addition, as the content of Nb_2O_5 increased, the diffraction intensities of the samples increased gradually. The microstructure observation revealed that Nb_2O_5 addition remarkably retarded grain growth when it below 0.85 wt %. And the addition of 0.85 wt % Nb_2O_5 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 (μ_i) initially increased up to a content of 0.40 wt% and showed a decrease at higher content up to 1.00 wt%. However, losses (P_L) changed contrarily. Saturation induction (B_s) decreased monotonously with increasing Nb_2O_5 content.