Cold sintering assisted processing of Mn-Zn ferrites

Typically, commercial Mn-Zn ferrites are sintered at high temperatures with prolong times. In this work, commercial Fe2O3-rich ferrite powders with the composition of 0.21Mn(0.8)Zn(0.2)Fe(2)O(4)-0.79Fe(2)O(3) (wt%) are densified by cold sintering at 300 degrees C with the assistance of organic salts, including MnC(2)O4 center dot 2H(2)O, FeC2O4 center dot 2H(2)O, and Zn(C2H3O2)(2)center dot 2H(2)O. Excessive Fe2O3 enters into spinel structure forming a solid solution through annealing in low pO(2) at 1350 degrees C. The sintering behaviors, microstructures, magnetic properties and impedances are investigated. The dehydration of organic salts provides mediate liquid phase to trigger the dissolution-precipitation process, which assists the densification of ceramics. The grains grow from 0.15 mu m to 0.52 mu m and 7.67 mu m after cold sintering at 300 degrees C and annealing at 1350 degrees C, respectively. The initial permeability of cold sintered sample is improved to 11000 with a Curie temperature of 125 degrees C. This work provides a feasible route for cold sintering assisted processing of commercial soft magnetic ferrites.

Automated summary

In this study, commercial Fe2O3-rich ferrite powders were densified by cold sintering at 300 degrees C with the assistance of organic salts, resulting in improved initial permeability and a Curie temperature of 125 degrees C. The dehydration of organic salts provided a medium liquid phase that triggered the densification process of the ceramics. The excessive Fe2O3 entered into the spinel structure forming a solid solution through annealing in low pO(2).