Microstructure and thermal analysis of lithium ferrite pre-milled in a high-energy ball mill

In this work, the effect of ball milling of synthesized LiFe5O8 ferrite powders on the microstructure and properties of ferrite ceramics was studied by XRD, laser diffraction and SEM analysis as well as thermal analysis. The mechanical milling of LiFe5O8 was carried out in a Fritsch Pulverisette 7 planetary mill using the zirconia or steel grinding balls. The process of ferrite sintering was investigated using dilatometric analysis. In addition, ferrite ceramics electromagnetic properties, including magnetization, Curie point and electrical resistivity, were investigated. The results showed a strong difference in the structure of ferrite ceramics obtained from ferrite powders pre-milled by zirconia or steel grinding balls. Thus, the milling results in a decrease in the particle size of the ferrite powders to ultrafine range. The ferrite ceramics, obtained from powder milled by steel balls, is characterized by high density and low porosity as well as good electromagnetic properties and the main presence of a disordered β-LiFe5O8 phase. However, the mechanical milling using zirconia balls leads to the contamination of ferrite by zirconia, resulting in the formation of β-LiFe5O8/ZrO2 composite ceramics during sintering.