Characterization of Elastomeric Composites With Lithium Ferrite Acting as Magnetically Active Filler

The influence of magnetic filler on magnetic and physical–mechanical properties of composite samples with the concentration varying from 100 to 600 phr (i.e., 17–55 vol.%) was studied. Magnetic polymer composites were synthesized by incorporation of soft magnetic filler in acrylonitrile-butadiene rubber matrix. Soft magnetic lithium ferrite powder substituted by Zn and Ti having the chemical composition Li0.525Zn0.30Ti0.35Fe1.825O4 with the addition of 0.005 Bi2O3 and 0.05 MnO2 prepared by the standard double-sintering ceramic process was used as the magnetic filler. Structural and magnetic characterization of Li ferrite carried out by means of X-ray diffraction analysis and measurement of the temperature dependences of magnetic susceptibility confirmed the single-phase cubic spinel structure of ferrite with Curie temperature $T{_{C}}=324~^{\circ }\text{C}$ . Fundamental magnetic parameters obtained from hysteresis loops confirmed the soft magnetic behavior of the ferrite filler. Magnetic properties of synthesized composite samples were evaluated from complex permeability measurements $\mu =\mu '-j\mu ''$ in the frequency range from 10 MHz to 6.5 GHz. Observed results acknowledged that the amount of lithium ferrite remarkably affects the properties of magnetic polymer composites, i.e., increasing ferrite filler amount caused increase of magnetic permeability as well as the hardness and elongation at break; on the other hand, the values of tensile strength at break decreased.