Dielectric, magnetic and microwave absorbing properties of 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 (FTIR), which shows that the spinel Co0.7Cr0.1Zn0.2Fe2O4 ferrites and the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites are obtained. As a small amount of Co2+ in the octahedron ferrite is replaced by Cr3+, the lattice constant of Co0.8Zn0.2Fe2O4 ferrites reduces from 0.8409 to 0.8377 nm. The magnetic properties of the two materials were investigated by vibrating sample magnetometer (VSM). The VSM results confirm that the saturation magnetization (Ms), remanent magnetization (Mr) and coercive force (Hc) of the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites are 8.80 mA·m2·g−1, 3.14 mA·m2·g−1 and 37.22 kA·m−1, respectively, which are smaller than those of the Co0.7Cr0.1Zn0.2Fe2O4 ferrites. The microwave absorbing capability of the two materials was studied by waveguide method. In the frequency range of 5–20 GHz, two reflection loss maximum values of the PANI-Co0.7Cr0.1Zn0.2Fe2O4 composites appear at 14.1 and 17.9 GHz with −13.17 and −15.36 dB, respectively, which are obviously higher than those of the Co0.7Cr0.1Zn0.2Fe2O4 ferrites.