Studies of magnetic, Mössbauer spectroscopy, microwave absorption and hyperthermia behavior of Ni-Zn-Co-ferrite nanoparticles encapsulated in multi-walled carbon nanotubes

To enhance the magnetization as well as to optimize the anisotropy of a mixed spinel nanocrystalline system, Ni2+, Zn2+ and Co2+ are chosen proportionally (0.3, 0.4 and 0.3) in Ni-Zn-Co-ferrite (NZCF). The nanoparticles of such Ni0.3Zn0.4Co0.3Fe2O4 (N3Z4C3) are prepared by co-precipitation method. Prepared nanoparticles are incorporated in the matrix of multi-walled carbon nanotubes (MWCNT) to enhance the microwave absorption. X-ray diffraction (XRD) patterns and their Rietveld analyses confirm the desired phases of N3Z4C3 and N3Z4C3-MWCNT. Distributions of cations in A- and B-sites are determined using Rietveld method. Morphological analyses are carried out by analyzing the observed electron-graphs recorded in high resolution transmission electron microscope (HRTEM). Magnetic and hyperfine behaviors are studied and interestingly, high magnetization (∼84 emu/g) is achieved at room temperature (RT). Microwave absorption capability is investigated by recording reflection losses (RL) in the range of 8-18 GHz. A maximum RL of ∼−22 dB is obtained at 15.24 GHz for 1 mm thick layer of N3Z4C3-MWCNT nanocomposite. Besides, microwave absorption study of Ni0.4Zn0.4Co0.2Fe2O4 (N4Z4C2) encapsulated in MWCNT is included for comparison. AC induction heating capability of NZCF nanoparticles for hyperthermia applications in cancer treatment is carried out and the same for Ni0.3Zn0.4Co0.2Cu0.1Fe2O4 (N3Z4C2C1) is included to make a comparative study. Among all the considered nanoparticles, N4Z4C2 nanoparticles with crystallite size (dcryst) of ∼34.7 nm exhibits maximum specific absorption rate (SAR) of 200 W/gFerrite. Our study suggests that NZCF nanoparticles are important for their applicability as good microwave absorber as well as efficient AC induction heat mediator.