Structural and magnetic investigation of Al3+ and Cr3+substituted Ni-Co-Cu nanoferrites for potential applications

Nanocrystalline Al3+ and Cr3+ doped Ni-Co-Cu ferrites with the chemical composition Ni0.7Co0.2Cu0.1Al0.5xCr0.5xFe2-xO4 (x = 0.0, 0.1, 0.2) were prepared for demonstrating their structural, surface morphological and magnetic characteristics. The technique used for synthesizing the doped and undoped Ni-Co-Cu nanoferrites was sol-gel auto-combustion technique. The existence of single phase was confirmed with the help of X-ray diffractometry (XRD) which indicates the presence of spinel cubic structure for the synthesized specimens. The crystallite size (D) was determined from the highest intense (311) peak of the observed x-ray diffraction patterns by Debye-Scherrer formula and it was found in the dimensions of 44-55 nm. FESEM micrographs shows the existence of agglomerated and spherical magnetic nanoparticles with an average grain size of 63-78 nm. The prepared samples were examined with energy dispersive x-ray spectroscopy for the analysis of purity of synthesized samples and thus, from the EDX spectrum, only peaks of nickel, cobalt, copper, aluminium, chromium, iron and oxygen were observed which confirms the high purity of our results to a next level. The magnetic study was taken into consideration by vibrating sample magnetometer (VSM) and therefore, from the M - H curves data, various magnetic parameters were calculated. From the M - H loops measurements, the maximum of saturation magnetization (M-s) observed was 52.49 emu/g along with few hundreds of coercivity (H-c) indicating the ferromagnetic and soft behaviour of synthesized specimens. Therefore, in the present investigation, excellent values of saturation magnetization (28.11-52.49 emu/g) and coercivity (536.6-591.02 Oe) were obtained making these nanoferrites suitable for the high-density recording media and electromagnets application.