Microwave Absorbing and Magnetic Properties of the Polyaniline-Co0.7Cr0.1Zn0.2Fe2O4 Composites

The spinel cobalt chromium zinc ferrites (Co0.7Cr0.1Zn0.2Fe2O4) and the polyaniline (PANI)-Co0.7Cr0.1Zn0.2Fe2O4 composites were prepared by polyacrylamide gel and an in situ polymerization method, respectively. The structure of the synthesized material was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FT-IR), which shows that the spinel Co0.7Cr0.1Zn0.2Fe2O4 ferrites and the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites are obtained. Because a small amount Co2+ ion of the octahedron ferrite is replaced by Cr3+ ions, the lattice constant of the Co0.8Zn0.2Fe2O4 ferrites reduces from 0.8409 nm to 0.8377 nm. The magnetic properties of the two materials were investigated using vibrating sample magnetometer (VSM). The VSM results confirm that the saturation magnetization (Ms), remnant magnetization (Mr) and coercive force (Hc) of the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites are 8.80 emu/g, 3.14 emu/g and 37.22 kA/m, respectively, which are smaller than those of the Co0.7Cr0.1Zn0.2Fe2O4 ferrites. The microwave absorbing capability of the two materials were studied by wave-guide method. In the measuring frequency range of 5.0 similar to 20.0 GHz, two reflection loss maximum value of the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites appear at 14.1 GHz and 17.9 GHz with -13.17 dB and -15.36 dB, respectively, which is obviously higher than those of the Co0.7Cr0.1Zn0.2Fe2O4 ferrites.