A study on synthesis and characterization of the core–shell materials of Mn1−xZnxFe2O4–polyaniline

Microwave absorbents with core–shell structure of Mn1−xZnxFe2O4–polyaniline have been synthesized by the polymerization of aniline in the aqueous solution of aniline in the presence of surfactant NaDS and the nano-particle size powder of Mn1−xZnxFe2O4. The nano-particle size of Mn1−xZnxFe2O4 was prepared with the method of self-propagation combustion of the aqueous sol–gel. X-ray powder diffraction of ferrites indicated that the structure of core materials is spinel structures with lattice constants around 8.44–8.40 Å. SEM and TEM photographs show that the particle size of core material are around 100–200 nm. After coating with polyaniline, the particle size of the core–shell of ferrite–polyaniline has grown up to 400–800 nm. The conductivity of the core materials ferrites and of the core–shell materials of the ferrite–polyaniline measured by the four-point probe resistivity are 10−5 Ω−1 cm−1 and 10−1 Ω−1 cm−1, respectively. The conductivity of the core–shell materials increase with the increasing of the amount of polyaniline in the resulting products. The magnetic hysteresis loops of materials investigated with VSM indicate that the saturated magnetization (Ms) of pure spinel ferrites of Mn1−xZnxFe2O4 increase with the x value up to 47.01 emu/g for Mn0.50Zn0.50Fe2O4, but the Ms values of the core–shell materials decrease with the amount of polyaniline (PAN) in the core–shell ferrite–polyaniline materials. The composite specimens of the core–shell ferrite–polyaniline and epoxide resin have bandwidth microwave absorption of the reflection lose −5 dB to −10 dB at the frequency between 4.5 GHz and 6.8 GHz were also observed by the network analyzer.